LU83044A1 - METHOD FOR MANUFACTURING A BEAM IN I COMPRISING A CENTRAL CORRUGATED CORE AND CYLINDERS FOR THE MANUFACTURE OF THIS BEAM - Google Patents

Description

D. 51.361 * ^ K, 'V Π Û / GRAND-DUCHÉ DE LUXEMBOURG ♦ Brevet N' ...... ££ ..... v V i * # ± du ... 3o December 198 O (( ¾¾¾)) Mr. Minister ,,,. , {7¾¾¾ of the Economy and the Middle Classes

Book title: m „. . T x „*„ .................................. Intellectual Property Service

'Slj / LUXEMBOURG

Invention Patent Application I. Request ... The ... society ... di tei ..... SUMI.TOm .... ^ ïM .... INmSTRIES./......LTD ... / ...... 15 ^ _5 = Sb.ÇffiP <l) ~ Kitahama, ..... Higasbirku., ...... Qsaka-sM, ..... Osaka. ,, ..... aa & QXkt ...... represented .....................

^ par-Monsieiir .... J acques ..... de Muvser, ..... acting as ....................... ..... (2) • agent ........................................ .................................................. .................................................. .................................................. ...............................................

deposit (s) this ......... tn: .ent.e ..... déc.cembr.e ..... lS.oo ..... guatr.er, y.in .gt .............................................. (3 ) at ........ .15 ........ ... hours, at the Ministry of the Economy and the Middle Classes, in Luxembourg: 1. this request for obtaining a patent for an invention concerning: ..... ".. process .of ... fabricat.iQn .... d ..! .. 'une ..... EQ.utre ..... en .... I ..... comprising ................................... (4). ........ a ..... soul ..... with ..... ripple ... cen.tr.ale ..... et..cy.l.lnd.res ..... E.our ..... la .................................... .................

......... manufacturing ..of ..... ce.tte ..... pQ.utr.e.ü .. * .............. .................................................. .................................................. ..................................

.................................................. ..................................... .......... ... .................................................. ... *** ...............,. J & .......................... ....................................... y .......... ..............

2. the delegation of power, dated ...................................... on .. ........ ¾¾ ....... iLLsîlL · ....................

3. the description in French ......... language .......................... of the invention in two copies; 4. .......... 8 .................. drawing boards, in two copies; 5. the receipt of the taxes paid to the Luxembourg Registration Office, on .......... December 3, l9..8.Q _________________________________________________________________________________________________________________________________________________________________________________________________________________ declare (s) assuming responsibility of this declaration, that the inventor (s) is (are): ..... see · -to · back ...................... .................................................. .........— ........................................ .................................................. ........................... (5) claims (s) for the above patent application the priority of one (or more) application (s) s) of (6) .................. patent .. ....................... ........................ filed (s) // (7) yy.j £ aPOR ........... .................................................. ...........................

le ...... 9 .... mai ..... 1.9.8ο .......... {No * ...... 6153.3 / 13 8oX - ^ JlfeJ2o .. „May„ „X9.aQL ..............-............................ ........ (8) .............. (Ko ...... 69414 / 13.80) ..... ί ....... .................................................. .................................................. .....................

in the name of ........ the applicant ..................................... .. ............................. ....... (9) acEiucIIe elects (elect) for him / her ) and, if appointed, for its representative, in Luxembourg ....................................

..... 35., ...... bld ...... Royal ............................ .................................................. .................................................. .................................................. ............................. (io) requests (s) the grant of a patent for the invention for the subject described and represented in the S annexas mentioned above, with postponement of this delivery to ................. LJ .................. .......................month. (11) •, \ Le ... Mandataire ........... k ......... ¾ ... \\

£ .......... L .... V

Ό '-v_î II. Deposit Minutes

The aforementioned patent application has been filed with the Ministry of Economy and Middle Classes, Intellectual Property Service in Luxembourg, on: 3 CS âAgy.br-g; IQSo / - - Pr. The Minister at. „. 15 .......... hours // / \ of the Economy and the Middle Classes, 15- | 'i p. d.

/ _ '' A G8007 W ·! . '..... V ✓

AT

1. - Masami HAMADA, 941, Kyuchu, Kashima-cho, Kashima-gun, Ibaraki-ken,

Jaj> on 2. - Kiyokazu TANAKA, 175o-l, Kyuchu, Kashima-cho, Kashima-gun,

Ibaraki-ken, Japan 3. - Takeshi KIKOCHI, 12-21, Minatogaoka, Kashima-cho, Kashima-gun,

Ibaraki-ken, Japan 4. - Yasuhiro ASAI, 426-4, Katori, Sahara-shi, Chiba-ken, Japan 5. - Chihiro HAYASHI, l-24-2o3, Tsukimigaoka, Nigawa, Takarazuka-shi,. .. Hyogo-ken, Japan 6. - Fumio OHTAKE, 2471-7, Habakari, Tonoshomachi, Katori-gun, Chiba-ken,

Japan CLAIM OF PRIORITY D. si.36i ------ ____ - ---- - * of patent application / ôŒincJdàteiB * Batte * J - - -

IN JAPAN

| Dü 9 May 1980 (N ° 61533/1980) I 20 May 1980 (N ° 69414/1980) I r- ’% t \ I i V; ; * 'O-;.

\):),! s SEEN

Brief Description filed in support of a request for

PATENT

at

Luxembourg on behalf of: SUMIΤ0Μ0 METAL INDUSTRIES, LTD.

for: Method for manufacturing an I-beam comprising a core with central corrugations and cylinders for the manufacture of this beam.

The present invention relates to a method of manufacturing an I-beam comprising a core with central corrugations, as well as cylinders used in this method.

A core of the I-beam exerts less effect on the sectional module of the latter than a structural element of bending. Consequently, during the manufacture of the I-beam, the core is made as thin as possible for reasons of saving material. Due to the increased demands which have arisen in recent years for lighter steel elements, the thickness of the web of the I-beam has been reduced more and more, however, from the point of view of resistance to shearing and buckling of the core, there is a limit in the thinning of the latter. Theoretically, it is known that the core of the I-beam can be made with a thickness less than the limit value by forming undulations there. However, it is a fact that an I-beam with a corrugated core has not yet been placed on the market as an industrial product, since it is very difficult to form corrugations on the core of a beam of this type.

It is therefore an object of the present invention to provide a method for economically and efficiently manufacturing an I-beam comprising a corrugated core.

Another object of the present invention is to provide cylinders for use in the process for the economical and efficient fabrication of the corrugated web I-beam.

Yet another object of the present invention is to provide a shape and dimensions of corrugations exerting an increased effect both on the shear and buckling resistance as on the resistance to lateral compression which are required for the core of the I-beam in current manufacturing technology.

The manufacturing process following the present invention is characterized in that the work of formation of the corrugations is carried out on the central zone of the core of the I-beam by means of two cylinders which mesh with one another in a complementary manner, so that there is no change in the main dimension of the I-beam, except in the thickness of the core.

The cylinders intended to be used in the process according to the present invention are characterized in that they each comprise, in their working surface, two grooves of the grooves for guiding the wings of an I-beam, as well as a corrugated zone extending between this grooves, these two cylinders coming to mesh in a complementary manner in the corrugated zones.

Given the fact that it is not always necessary for the cylinders to provide stress-guided guidance on both sides of the wings of the I-beam and it suffices to guide one of the sides of each of the wings to center this beam, the present invention envisages a modification of the cylinders according to which it is avoided having to form grooves in each of them and adjusting the spacing of these grooves as a function of the width of the wings of the beam.

The invention will be better understood on reading the description below given with reference to the accompanying drawings in which: Figure 1 is a schematic illustration of a production line for the implementation of the method according to the present invention; Figure 2 is a cross-sectional view of an I-beam made by the method according to the present invention; Figure 3 is a longitudinal sectional view taken along line III-III of Figure 2; Figure 4 is an enlarged partial longitudinal sectional view of a corrugated part in the central area of the core of the I-beam made by the method according to the present invention; FIG. 5 is a diagram illustrating the relationship between the amplitude of the corrugations / thickness of the core and the resistance to shearing and buckling; Figure 6 is a schematic illustration of a test in buckling mode due to a laterally concentrated force; FIG. 7 is a diagram illustrating the relationship between the ratio of the width of the corrugations / height of the core and the resistance to shearing and to buckling; FIG. 8 is a diagram illustrating the relationship between the ratio of the width of the corrugations / height of the core and the resistance under a load concentrated laterally; Figure 9 is a vertical sectional view of the corrugating cylinders according to the present invention; Figure 10 is an enlarged partial sectional view i i of the body of one of the cylinders illustrated in Figure 9; FIG. 11 is a front sectional view of the cylinders according to the present invention, used in the production line of FIG. 1; ! Figure 12 is a partial sectional view of an embodiment of the cylinder according to the present invention; ί Figure 13 is a partial view of another form. for producing the cylinder according to the present invention; s. Figure 14 is a cross-sectional view of the wing guide, taken along the line XIV-XIV of Figure 13; s i Figure 15 is a partial sectional view of yet another s embodiment of the cylinder according to the present invention; Figure 16 is a front view of the wing guide,% taken along line XVI-XVI of Figure 15; Figure 17 is a partial sectional front view of the cylinders according to the present invention, this view illustrating another mode of use of these cylinders in the production line; FIG. 18 is a diagram illustrating the distribution of the residual stress in the corrugated core of the I-beam; . . FIG. 19 is a diagram illustrating the deflection curve as a function of the load during the lateral compression test; and FIG. 20 is a diagram illustrating the deflection curve as a function of the load during the shear and buckling resistance test.

The manufacturing process and cylinders according to the present invention will be described below with reference to these drawings. As illustrated diagrammatically in FIG. 1, in the production line intended for the implementation of the method according to the present invention, an ordinary beam 1 in I is corrugated by means of the cylinders 2 according to the present invention in order to obtain a machined beam 3 in I comprising a corrugated core.

The ordinary I-beam can be a welded or hot-rolled I-beam. The formation of the corrugations by the cylinders 2 can be carried out by hot or cold machining.

The manufacturing cylinders 2 will be described below in more detail with reference to FIGS. 9 to 17.

The I-beam 3 machined by the method according to the present invention is corrugated not over the entire width of its core 31, but only in the central part thereof. Since a flat part 311 is left intact in each of the edges of the core, the formation of the corrugations is easily carried out without exerting any unfavorable influence on the junction between the core 31 and the wings 32 of the beam 3 in I.

Although it is difficult to envisage a theoretical analysis of various factors such as the forces required for the formation of the corrugations in the process according to the present invention, repeated tests demonstrate that the most exact approximation is not an equation theoretical deep drawing, but although theoretical cold rolling equation in combination with a theoretical bending equation in U.

The most approximate theoretical equations are as follows: P -P1 * 'r2 = 2σ · Cj / RAt P2 = 2C * t * σ (1 + t / L) + 2C * t2 * a / L where P: rolling load P ^: cold rolling load i

P 2: bending load in U

[o: tensile strength | C: width of the undulations | t: thickness of the core L: no undulations

At: reduction in thickness of the core

Assuming that the length in extension of the core resulting from the rolling forms the corrugation, the depth δ of the latter (see FIG. 4) is expressed by the equation below, the effectiveness of which has been confirmed by tests: δ = 2L · (1 - cos ^ 6Φ) where Φ: reduction rate

Although a single pass is sufficient to form corrugations in the web of the I-beam, two or more passes are preferable to obtain a product free of camber or torsion, since the configuration of the corrugations changes within a tr ^ s small measurement during the second pass or a subsequent pass, thus giving rise to a desirable redistribution and reduction of the residual stress.

Preferably, the dimensions making it possible to determine the shape of the corrugations by the method according to the present invention are chosen in the following intervals: i. 9.3t <L <36t ii. l, Ot <f <3.9t

iii. 0.5h C <h - L

The letters appearing in these intervals designate the dimensions of the parts of the beam in, I which are illustrated in FIGS. 2 and 4, namely: t: thickness of the core h: height of the core f: amplitude of the undulations C : ripple width L: not ripple

These intervals are obtained as described below.

(I) Possible manufacturing interval

As shown in Figures 2 and 3, the corrugations are formed perpendicular to the axis of the beam. Although the hollows and ridges should be arranged alternately to avoid eccentricity, they need not always be continuous, with planar portions which may extend between the hollows and crests of the corrugations. The waves can have a trapezoidal shape rather than the shape of a wave. However, during manufacture, since the rate of elongation of the core material during rolling intended for the formation of corrugations is preferably as low as possible and that, in the case of the same rate of elongation, the number of hollows and crests provided in the specific length is preferably as high as possible to obtain an optimal effect, these hollows and crests are preferably continuous.

Repeated tests of wave formation show that an elongation rate of 12¾ or less during the formation of waves is within a favorable range.

(2) Pitch (L) and amplitude (f) of the undulations

One effect of the corrugations is to increase the flexural rigidity of the core in a direction perpendicular to the axis of the beam. The preponderant factor intervening in the increase in the rigidity with bending is the amplitude f of the undulations.

FIG. 5 illustrates the relation existing between the amplitude of the corrugations / thickness of the core (f / t) and the shear and buckling resistance (rf). The resistance to shear and buckling (r) depends on the width of the corrugations (C) and the thickness of the core (t). The tests were carried out on I-beams having the configuration to which it is considered that the method according to the present invention is most generally applied, the thickness t of the core being equal to h / 120, while the width C ripples is equal to 0.75h. As shown by the curve in FIG. 5, the resistance rf increases parabolically as a function of the increase in the amplitude f of the undulations.

Although the increase in shear strength resulting from the presence of the corrugations is obtained despite the reduction in the thickness of the core (t), the expenses devoted to the formation of the corrugations are not amortized, unless that the amplitude of the latter is not sufficient to reduce the thickness of the core by at least 25¾. Since the shear and buckling resistance of the planar core is pro-? portable at (t / h), a reduction of 25¾ in the thickness of the core gives rise to a reduction in resistance of approximately 50¾. Consequently, in order to compensate for the reduction in resistance resulting from the presence of the corrugations, the amplitude of the latter! must be determined so that the resistance of the soul; corrugated reaches twice or more the resistance rf ^ of a plane soul j jf = 0). Consequently, the value of f is obtained according to the i formula f / t> l as shown in FIG. 5.

Preferably, the pitch L of the corrugations is also as small as possible in order to ensure a lower turbulence of the stresses and a better stability with respect to a force F concentrated laterally. As shown in Figure 6, tests for the laterally concentrated force indicate that local buckling occurs in the core near the point at which the force is applied and that the length of the buckling wave C reaches approximately 0.4h. This resistance is important in determining the configuration of the core. In order to obtain this stabilized resistance at any position, it is necessary to determine the pitch L of the ripple, so that the length J of the buckling wave includes at least two waves of the ripple. Consequently, the pitch L of the corrugation must be 0.2 h or less. On the other hand, the pitch L and the amplitude f of the corrugations depend on the elongation produced during manufacture, i.e. - say that the value L / f decreases as the work elongation increases due to the formation of the corrugations. In order to limit the rate of work elongation to 121 or less as described above, the value L / f must be greater than 9.3 (L / f> 9.3).

As described above, the configuration of the corrugations is subject to three limitations relating to the yield and the machinability. Furthermore, assuming that the practical interval concerning the thickness of the core is> t î>, the interval for the step L of the undulations is -JL- ^ L Z - JL- on 9.3t ^ L 36t. while at the interval the amplitude f of the undulations is <f <or l, Ot <f <3.9t.

(3) Width of the corrugations (C)

The width C of the corrugations is most closely related to the shear and buckling resistance of the beam, as well as the resistance of the latter under a laterally concentrated load R. Figure 7 illustrates the existing relationship between the ratio of the width of the corrugations / height of the core (C / h) and the shear and buckling resistance t ^, for example, in the case of h / t = 120 and f / t = 1.3. In Figure 7, the black dots represent experimental values, while the solid line curve represents analytical values. As described above, the shear and buckling resistance of the corrugated core must reach twice or more the resistance tCq of the planar core (C = 0). Consequently, according to FIG. 7, the value of C / h at which the resistance lies within this range, is C / h ^ 0.5.

FIG. 8 illustrates the relation existing between the ratio ripple width / core height (C / h) and the resistance under the laterally concentrated load R. From this figure, it can be seen that the ratio C / h of 0 , 5 or more gives waves with sufficient effect. In the case considered Fh Et '' here, R = —ψ—, where D = - = -, E is the elastic modulus and "12 (1-7) 7 is the Poisson ratio. In figure 8, the black dots represent experimental values, while the curve in solid lines represents the experimental equation R = χ 5-C7h '

Consequently, C / h ^ 0.5 constitutes the effective practical interval for the formation of undulations in the central part of the core in order to increase the shear and buckling resistance of this core, as well that its resistance under the laterally concentrated load R. The upper limit of the value C / h is defined by the working limit and the turbulence of the stress generated in the wing of the beam. In other words, "1 terms, if the width C of the corrugations is too large," I observe deteriorations not only because the wing of the beam is subjected to an undulating movement during the for-matioa of the corrugations , but also because a significant stress is generated at the junction between the core and the wing.

* Manufacturing tests show that there is no problem * if the width of the non-corrugated part is equal to 6t or J more or to 0.5L or more. In addition, these tests confirm that the turbulence of the stress to which the wing of the beam is subjected following the formation of the corrugations, has no effect if the width of the non-corrugated part is equal to 0.5L or more.

Consequently, the effective interval for the width of the corrugations is defined as 0.5h or more, (h - L) or less and (h - 12t) or less.

The manufacturing cylinders 2 intended to be used in the process according to the present invention have the configuration illustrated in FIGS. 9 and 10. As shown in FIG. 9, each of the cylinders 2 of a pair comprises, in its working surface, grooves 21 spaced from each other by a distance corresponding to the height h of the core (see FIG. 2) of the beam 1 in I as blank material, in order to guide the wings of this beam, as well as a corrugated zone 22 having the width C (see FIG. 2) extending between these grooves 21 As shown in FIG. 10, the corrugated zone 22 has a configuration defined by a primitive radius P, radii of curvature of waveform r ^ and r2, the ripple pitch L, the wavelength ^ and the ripple width C. The relation between these dimensions is determined according to the dimensions of the I-beam of such so that the main dimension in section of the latter does not undergo any change, except in its zone d e formation of ripples.

In this embodiment, each of the manufacturing cylinders * has, on its working surface, two grooves 21 intended to guide the wings 32 of the I-beam 1 to be machined. Consequently, the cylinders of this embodiment have a drawback because a limitation is imposed on the width of the core 31 of the I-beam to be machined; in other words, these cylinders lack flexibility of use. In particular during cold forming for which the rolls must be made of a high alloyed steel of high hardness, the manufacture of the rolls of this embodiment poses an additional problem because it is extremely difficult to form narrow and deep guide grooves.

These problems are solved by means of the cylinders of various other embodiments of the present invention which will be described below with reference to FIGS. 11 to 17.

In the embodiment illustrated in FIG. 11, the bodies of two corrugation cylinders 2, 2 have a width corresponding to the height h of the core of the I-beam, more precisely, a width slightly less than this height h, so that the wings 32 of the I-beam are spaced from the engagement surface between the cylinders 2, 2.

In addition, the upper cylinder or the lower cylinder is provided with guides 4 for the wings of the beam. For example, in the case where the wing guides 4 are provided in the lower cylinder 2 as shown in FIG. 11, these guides 4 are fitted on the pin 23 on either side of the body of the lower cylinder 2, their axial positions being adjusted before fixing them j on the pin 23 in coincidence with the positions of the wings 32 of the beam 1 at I.

Different means are used to fix these guides | of wings 4. For example, as shown in figure 12, the touril- | Ion 23 of cylinder 2 can be threaded to screw a collar 5 ii which is interposed between the body of cylinder 2 and the wing guide! Ji 4, so that the latter is held in place and tightened firmly by a nut 6 screwed from the outside.

As shown in FIGS. 13 and 14, the wing guide 4 may comprise a partial radial groove in the form of a slot 41 and another slot-shaped groove 42 extending to the central passage on the side opposite the groove 41 , so that the wing guide 4 can be made to slide along the pin 23 using the expansion and contraction provided by the slot-shaped grooves, to bring it into the chosen position in which the groove in the form of a slot 42 is tightened by means of a suitable element 43 such as a bolt, which has the effect of narrowing the central passage of the guide 4 and of fixing the latter.

As shown in Figures 15 and 16, the guide! wing 4 can have the diametrical grooves in the shape of! j slots 41 and 42, as well as a dry threaded engagement part! decreasing tion 44 on which is screwed a locking nut 45, so as to narrow the central passage of the .guide of wing 4 and thus fix the latter.

Thanks to these different types of fastening elements, the wing guides 4 are fixed to the pins 23 of the cylinder 2 in order to guide the wings 32 of the I-beam 1 from the outside. Since the wing guides 4 can be located in the desired position on the journal 23 of the cylinder, the positions in which these guides are fixed, are not determined by the height h of the web of the beam 1 in I Since it is not necessary to fix the wing guides 4 in asymmetrical positions, the core can be corrugated along an off-center line as shown in FIG. 17. These eccentric corrugations can be effective in some cases, for example, depending on the state of the load applied during the use of the I-beam, as well as the connection relationship with other organs.

The ripple forming cylinders according to these embodiments of the present invention offer advantages, in particular that they are widely applicable, for example, to the formation of eccentric ripples, without their positions being determined by the height of the web of the I-beam, while they exert an excellent guiding effect, noted a better stabilized centering on the work surface, since they can establish an effective guiding distance longer than compared to conventional cylinders , not to mention that they are easier to manufacture.

Table 1 below illustrates specific examples ie implementation of the method according to the present invention.

j ---- \ - T ----------------

O

9%

VO

X

to iv ·

! LO O

I K ^ O O O O

, m ^ * »iv n„ Nf r-t OrvJrHvO O CM O t "^ ι i O to o to

OO CH (M

X

to * »t- ·.

O

to "X ^ ^ Λ 0 0 ^ il Ν ο N LO 5 ο · Η dd" * * 3- oo o oo p

m 1 ~ ^ Λ Τί ·. #v U

^ 'd-rM O-tMiHVOTl O CM Ο Γ- If "CM | | LO tO 0 LO to“ o o ^ ^ § * 2, -Γ §%? 13 tfl + j s e ë 8 CM' O rH PL.

___ rH (U 3 ε. "- i. Q) <0 H Ψ ^ 0 3 ^ <D 2" x 0 u vj) g "® O £ g £ i“ 2 "^ o§o ® ä 'CM OO O ·> OOOO _, Eh 00 O ÏÏC ™ “t ^ -o - SG -vo ° to

6-1 X ^ to O “H O LO> 2 O o r — i Ο Ό 1 i S

I to ^ 2 * ° 2 2 M g to ^ • v ch y tn p y u.

Ό VO ^ ÜP § g X P g Su ij ^ S υ V0 ö 3 to 1S d ^ 0 .B1

Q S d) W

Csî ö ^ p 's ς? ε or | = <S '-' <- 'V—' î-l _ co U tn 4_> -, * 0 t /> U <Λ 3 '-> tfi 3 15 P .g m S 2 S o c ο o

Lj ’ö ï! g S V) O / -% · Η ΙΛ Ο / "" \ · Η Ci,

X E 0 p 3 ß · Η _q + j C-Hh3 + J

> i Η O o + j '-' cö O + J '-' CÖ Cö

-E'QH-Hoj rH · Η cö rH rH

P, H + -> iH 3 3 + -> rH t /> 3 i — j'H00 3 3 3 33 03¾1¾ m X 'd' Γ1 9P ^ Ή 33 O 3 rH 33 O ß T) mSfc * iS3.2S , HO 3 3 · Η ow> U 3 ß 33 O -P 33 O -P 0 1! vr '0' bc rt "n ß 3 ß e * Xf -" </} EgO (/) r- (0 G (Γ, r— (0 <g Î "_, P0Sro 0 3 33 u 3 * 3 * T3 rH rH Cfi 33 33 ΙΛ 33 33 ri 0 0 ß P 0 Ö p 33 PO 3 0 0 h ΐ -Ö 3 0 3 0 rg H 0 3 P 0 to 33 £ P 0 in 33 ß p tn + J00 3 tn 0 ß o 3 in 0 ß o in g 0 (Λ T3 0 · Η G (Λ τ3 Ο · Η 3 ο PP b B4 "Η VHtf) Ο0 · Η mtn 0 ft + j> cö3 ÎU C3 to ο î-ί 5-irötnofH Cn Γ'ίιί0 “fttjho rtOL, cö? -IO tn

: cü> öCJO ^ IW & iCmH ^ SwCuChE- -H

1-1 ___ 3 0 0 (Λ

^ * Ö 0 I to I in X

m 2 I J3Gy l 3C3W

* 2 y, c ώ 'Soco rt T3 O 0 0 S S n 9 EÖC * H3w p Ö Ö Η Ό «Λ 2 9 9‘Ί îhoo + j co hoo + j to

‘Z ïl Tl id P -H - 3 3 3 Ο -Γ-. - 3 3 3 -P

g P P ^ | 3,4 -> - 3rH0Pj ^ 0 33 E 3

As indicated in Table 1 above, the examples “of implementation of the method according to the present invention which are illustrated therein, make it possible to obtain I-beams comprising practiced the desired corrugated cores. The developed length of the curve of the corrugated area is greater than the total straight length of the web material and the increase in this developed length corresponds to the reduction in thickness of the web.

When corrugations are formed in a single pass in an I-beam of a short length of the order of 1.5 meters, there is a twist which is however eliminated by means of a second pass of formation of corrugations. In the case of a large X beam with a total length of 6 meters or more, there is apparently no torsion following a treatment in a single pass but, when this beam is cut into short lengths, the stress internal is released and a twist may appear. In an I-beam subjected to a wave formation treatment in two or more passes, no torsion is observed, even during sectioning in short lengths.

FIG. 18 illustrates the distribution of the residual stress in the corrugated I-beam indicated in the central column of table 1 and measuring 256.5 x 87.4 x 2.3 x 4.7, respectively after formation of corrugations in a single pass (small white circles) and after a second pass of wave formation (small black circles).

FIGS. 19 and 20 illustrate the results of tests of resistance to lateral compression and of shear and buckling resistance, respectively, carried out on an I-beam comprising a corrugated core and on an ordinary I-beam with flat core. In these figures, the solid lines represent the experimental results concerning the corrugated I-beam, while the lines in broken lines represent the experimental results concerning the ordinary I-beam.

The pontoon boats tested measured 212 x 68.6 x 2.0 x 4.6.

%

In these tests, a 100-ton machine was used and the deflection was measured using two dial gauges.

As these experimental results indicate, the resistance to lateral compression of the corrugated I-beam reaches approximately three times that of the ordinary I-beam, while its resistance to shear and buckling is approximately 1, 4 times that of this ordinary I-beam.

Table 2 below indicates the dimensions of the ordinary light and welded I-beams of conventional design, as well as those of the I-beams with corrugated core manufactured by the process according to the present invention. The conventional I-beams illustrated in this table are chosen from those whose shear and buckling stress is greater than the elastic limit. The I-beams with corrugated core have dimensions identical to those of conventional I-beams with regard to their height H and the dimension δ of their wings (see FIG. 2), but they comprise a core of a smaller thickness t . If the thickness of the core is reduced without forming corrugations therein, the shear and buckling resistance is reduced to approximately 30¾ of the elastic limit. However, in I-beams with corrugated core, the shear and buckling resistance of this core is maintained beyond the elastic limit thanks to the effect exerted by the formation of corrugations.

In Table 2, the corrugated area is not involved in the calculation of the yield of the flexural behavior, since the axial rigidity of this area is considerably reduced. As this table shows, the rate of flexural stiffness per unit of weight can be increased from 9 to 131 by forming undulations in the web of the beam.

- 18 - 'Table 2 *

Classical process Method of the present invention comparison (I) Material ”JISG 3353" (II) Material of corrugated core Bending ratio „, per unit of weight (Width of the corrugations) (II / I) 1200 x 100 x 3, 2 x 4.5 200 x 100 x 1.6 x 4.5 1.09 (150) 250 x 125 x 4.5 x 6.0 250 x 125 x 2.0 x 6.0 1.13 (180) 300 x 150 x 2.5 x 6.0 300 x 150 x 2.3 x 6.0 1.10 (220) 400 x 200 x 6.0 x 12.0 400 x 150 x 2.7 x 12.0 1.09 (300) / -

Bending ratio per unit of weight

Flexural stiffness

Weight of the classic I-beam of the corrugated I-beam Weight of the corrugated I-beam 'Flexural stiffness of the classic I-beam

Although certain specific embodiments of the present invention have been illustrated and described, it will be understood that these embodiments are given simply for purposes of illustration and description, various other embodiments being able to be envisaged without departing from them. of the scope of the present invention as defined in the claims below.

Claims (7)

1. A method of manufacturing an I-beam comprising a core with central corrugations, characterized in that it consists in forming corrugations in a central part of the core of a finished ordinary I-beam using two cylinders s '' meshing one with the other in a complementary way. 2. Method for manufacturing an I-beam comprising a core with central corrugations according to claim 1, characterized in that the corrugations are formed under the following conditions: 9.3t <L <36t 1.0t <f <3, 9t 0.5h <C <h - L where t: thickness of the core h: height of the core f: amplitude of the undulations C: width of the undulations L: pitch of the undulations 3. A method of manufacturing an I-beam comprising a core with central corrugations by forming corrugations in a central part of the core of an ordinary I-beam by means of two cylinders which mesh one in the another in a complementary manner according to claim 1, characterized in that the increase in the developed length of the corrugated core with respect to the rectilinear length of the planar core before these corrugations are formed is effected by reducing the thickness of the core following the formation of corrugations, without consequently entailing any change in the main dimension of the I-beam, except in the thickness of the core thereof. 4. Method for manufacturing an I-beam comprising a core with central corrugations by forming corrugations in a central part of the core of an ordinary I-beam at! - 20 -r by means of two meshing cylinders one in the other in a complementary manner according to claim 1, characterized in that the corrugations are formed in two or more passes in order to improve the state of the residual stress, as well as the camber or the torsion of the corrugated I-beam. 5. Cylinders intended for the manufacture of an I-beam comprising a core with central undulations, characterized in that they each comprise, in their working surface, two grooves intended to guide the wings of an I-beam, thus that a wave-shaped corrugated zone extending between these grooves two of these cylinders which mesh with one another in a complementary manner in the corrugated zones, j 6. Cylinders intended to form corrugations in the core of an I-beam, characterized in that they constitute a pair and each comprise a rolling body corresponding to the width of the core of the I-beam, corrugations which mesh with one another in a complementary manner being formed in the central part of these bodies, while guides for the wings of the beam are arranged on either side of the body of each of these cylinders respectively, these wing guides being rigidly mounted with the possibility of adjusting the axial position, while they have a diameter greater than that of the body of each cylinder. 7. Cylinders intended to form corrugations in the core of an I-beam according to claim 6, characterized in that the wing guides are arranged asymmetrically with respect to the body of the cylinder, on the axis of this latest.