US3552175A - Methods of permanently elongating strip - Google Patents

Methods of permanently elongating strip Download PDF

Info

Publication number
US3552175A
US3552175A US708947A US3552175DA US3552175A US 3552175 A US3552175 A US 3552175A US 708947 A US708947 A US 708947A US 3552175D A US3552175D A US 3552175DA US 3552175 A US3552175 A US 3552175A
Authority
US
United States
Prior art keywords
strip
strain
stress
bend
elongation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US708947A
Other languages
English (en)
Inventor
Martin G Kinnavy
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bank One Corp
Salem Corp
Original Assignee
Salem Corp
Union Savings and Trust Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Salem Corp, Union Savings and Trust Co filed Critical Salem Corp
Application granted granted Critical
Publication of US3552175A publication Critical patent/US3552175A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D1/00—Straightening, restoring form or removing local distortions of sheet metal or specific articles made therefrom; Stretching sheet metal combined with rolling
    • B21D1/05—Stretching combined with rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D25/00—Working sheet metal of limited length by stretching, e.g. for straightening

Definitions

  • a strip is permanently elongated by applying a tension force to it and constraining it while under tension to at least one bend and at least one bend reversal which causes yielding and an incremental elongation strain that is produced between a bend and a subsequent bend reversal in which the magnitude of incremental elongation strain is related to the applied tension force and the applied bending strains.
  • This invention relates to a method of permanently elongating strip material to remove irregularities in shape 1 and to modify physical properties or structure.
  • Simple jaw stretcher leveling is applicable only to the stretching of material in sheet form and not to a continuous process. Nevertheless, the idea of simple stretching has been applied to stretching of strip continuously. In this process the essential components are a drag bridle, a drive bridle, a suitably powered mechanical drive system, and the associated controls. While this process, at first glance, embodies the simplicity of the simple jaw stretcher, close examination discloses serious, but not obvious, weaknesses:
  • roller leveling process Another well-known method to level strip is the roller leveling process.
  • This process is applicable to sheet leveling and to continuous strip leveling. It consists of passing the material between two sets of rolls placed relative to each other so that the strip is constrained to a tortuous path, thereby causing flexing of the material in alternate directions.
  • This process is known to level strip.
  • the Work rolls are small in diameter and tend to diminish in size as the strip thickness to be processed is decreased. For example, one manufacturer uses inch diameter rolls for a thickness range of 0.010 inch to 0.050 inch and 1% inch diameter rolls for a thickness range of .015 inch to .064 inch.
  • Roller levelers are of two types, driven and non-driven or pull-through.
  • a serious defect associated with the former type is the strip marking caused by the velocity mismatch between the strip and the driven rolls.
  • the velocity mismatch arises as the strip is elongated in the process, and for which no provision is readily made in the roller drive system.
  • Attempts to overcome this operational defect have been made by using adjustable slip clutches in the drive systems, as well as by resorting to other nonpositive drive means, e.g. hydraulic drives.
  • roller leveler with a skilled operator at the controls can produce acceptable strip from an appearance point of view.
  • leveled strip is subsequently slit into narrower coils.
  • Different residual stress patterns exist across the width of the strip.
  • there appears in the plane of the strip another system of stresses which when disturbed by a slitting operation produces objectionable edge bow in the slit coils.
  • many machine builders have incorporated tension bridles to the roller leveling process, This has produced an improved product and has allowed the processors to handle strip of lighter gauge than could be leveled without tension.
  • the present invention is a new process of permanently elongating metal strip. This can be used to remove strip irregularities or to modify the physical properties of the strip among other uses. For any given set of physical properties of the strip material, one can assign combinations of tension and bending radii such that the desired strip elongation will be produced, and the desired effects, including levelng and modification of physical properties will result. It is possible that an arbitrary combination of tension and bending will produce some elongation. These arbitrary combinations, however, of tension and bending will not produce the result sought whereas the new process will produce the desired result with great accuracy.
  • the advantages of the new process are: low maintenance of equipment, low downtime of equipment, no strip marking caused by the differential velocity between driven rolls and strip, prolonged life of bridle roll covering, relatively low tension requirements, simplicity of control, ease of operation, and no restrictive speed limit. Furthermore because the new process relates tension with radius of curvature of bending in a prescribed manner, one is able to optimize tensions and roll diameter combinations to achieve the desired result. By doing this one is no longer limited to the use of small diameter rolls. This can eliminate the design complexity of a backup roll system as well as the operational difliculties associated with such systems including but not limited to strip marking.
  • Leveling.Leveling is a process by which shape irregularities in metal strip are removed so that the strip appears uniform. Leveling removes wrinkles from strip but not gross irregularities such as coil set or roll set (defined infra). Leveling makes all fibers of equal length in any given plane. The fibers, however, may vary in length from plane to plane throughout the thickness and the strip will still be leveled. The strip may have roll set or coil set and still be leveled.
  • Coil set or roll set A distinction must be made between local strip irregularities removable in a leveling process and the strip condition known as roll or coil set. If a length of strip assumes a longitudinal curvature when it is free of restraint, it is said to have roll or coil set. It is possible for a length of strip to have roll set with or without irregularities. Strip with roll or coil set, but without irregularities, is considered herein to be leveled strip. A simple multi-roll flattener can remove coil set from strip, but it generally is incapable of removing strip irregularities. If one considers strip to be comprised of a multitudinous array of fibers, each fiber in flat and leveled strip wil have the same length.
  • Strip with coil or roll set will correspond to a linear variation of fiber length throughout the thickness of the strip. If this pattern of variation is identical in a transverse direction, the strip is said to be leveled. If this variation changes in a transverse direction, the strip would have shape irregularities in addition to roll or coil set. Coil or roll set is related to what is called transverse bow by Poissons Ratio, a physical property of the strip.
  • I provide a method of permanently elongating strip which comprises, applying a tension force to the strip, and constraining the strip while under tension to at least one bend and at least one bend reversal which causes yielding and an incremental elongation strain that is produced between a bend and a subsequent bend reversal in which the magnitude of incremental elongation strain is related to the applied tension force such that when the yielding occurs on alternate sides of the strip on successive sive bends the increment of elongation strain follows the equation r-l- R2 Ae 2tey I provide a method of permanently elongating strip which comprises, applying a tension force to the strip, and constraining the strip while under tension to at least one bend and at least one bend reversal which causes yielding and an incremental elongation strain that is produced between a bendand a subsequent bend reversal in which the magnitude of incremental elongation strain is related to the applied tension force .such thatwhen yielding occurs on at least oneside of the strip at a bend and on both sides of the strip
  • FIG. 2 is an idealized stress-strain diagram
  • FIG. 3 is a diagram showing yielding on tension side of the stripknown as Case I;
  • FIG. 4 is a diagram showing yielding on'both tension and compression sides of the strip-known as Case II;
  • FIG. 5 is a diagram of strip-elongation upon bending strain reversalCase II;
  • FIG. ,6 is a diagram of strip elongation upon bending strain reversal-Case I;
  • FIG. 7 is a diagram showing different regions of" elongation and bending strain parameters
  • FIG; 8 is a schematic diagram: of app'aratusused in examples of, application. of method to strip 'material;
  • FIG.9.- is atable -showing'. incremental elongation strain for Case. IA, Case IB and Case II. 1' C Elongation-of strip-is related to leveling. This relationship can be shown by referring to an idealized stressstrain diagram for an elastic perfectly plastic material as shown in FIG. 1.
  • an idealized stressstrain diagram for an elastic perfectly plastic material as shown in FIG. 1.
  • each fiber so elongated will have the same stress. This is illus-. trated in FIG. 1 in which Point 1 shows the stress and strain for the longest fiber, and Point 2 shows the stress and strain for the shortest fiber.
  • Point 1 shows the stress and strain for the longest fiber
  • Point 2 shows the stress and strain for the shortest fiber.
  • any strain distribution may be considered to consist of an elongation component and a bending component.
  • the elongation component is the strain that exists at the middle of the strip; the bending component is zero at the middle of the strip and is maximum at the surface of the strip.
  • Strain components are designated in terms of the yield strain ey.
  • the extension component of the strain is the extension component of the strain and [Sky is the bending component of the strain.
  • Two strain distributions are shown on the lefthand sides of FIGS. 3 and 4 in which the vertical line is taken as the zero strain axis, and strains to the right of this line are taken as tension strains.
  • the stress distributions corresponding to these strain distributions are obtained by utilizing the stress-strain diagram, FIG. 2, together with the strain distributions shown. These stress distributions are shown at the righthand sides of FIGS. 3 and 4.
  • the force per unit Width of strip corresponding to the Case I stress distribution will be given by
  • a similar calculation for the Case II stress distribution will show that the tension force per unit width of the strip will be given by
  • the geometrical relation between bending strain and curvature is given by where R is the radius of curvature of the neutral fiber of the strip.
  • FIG. 5 shows a strain distribution by means of the line at the left side of the figure, this line labeled 1.
  • the surfaces of the strip are indicated by the horizontal lines at the top and bottom of the figure and the middle fiber of the strip is so labeled.
  • the stress distribution which corresponds to this strain distribution is obtained through use of the stress-strain diagram FIG. 2, and is shown at the right of FIG. 5 by the series of straight lines 11*110. This stress distribution is in equilibrium with the force per unit width of strip F ayt.
  • Point 2* is located at a distance l i ayt 2 2B 2 above the middle fiber. It now follows directly from geometry that the increment of elongation strain of the middle fiber, Ae is Use of the earlier stated geometrical relation between bending strain, strip thickness, and radius of curvature in this equation yields a more useful expression for the incremental strain produced during bending strain reversal under maintained tension, namely,
  • Case IA stress distribution For simple Case I stress distributions to transform into simple Case I stress distributions upon the reversal of the bending strain, hereafter called a Case IA stress distribution, the requirement is (Case IA)
  • Case IB stress distribution In some cases, a simple Case I stress distribution is transformed into a simple Case II stress distribution, hereafter called a Case IB stress distribution, and the condition for this is that (Case IE) or equivalently,
  • the process relates to the extensio'mof strip that occurs while subjectedtqa tension force from a simple. stress distribution which is associated with a bending strain, to a subsequent simple stress distribution, which is associated with a bending strain of opposite sign; In these instances the previous strain history will not be evident in the stress distribution; however the slope oil -the. elastic portion ofthef stress dis.- tribution will not bethe same as the slope of the strain. distribution.
  • the apparatus used in these examples consisted essentially of a means to apply a tension force to the strip and a means to produce bending strains and bending strain reversals.
  • the means of applying tension force was a hydraulic cylinder which was connected to a force 'gag'e which was connected to one end of the strip.
  • the other end of the strip was connected to a force gage which was connected by a bracket to a fixed building carried on a cart riding on a smooth track.
  • a hydraulic power supply was used to provide a ---source of hydraulic pressure for the hydraulic cylinder.
  • the hydraulic cylinder is used to remove slack from the strip; then a gage length is marked on the strip (50 inches).
  • a suitable tension force is then applied to the strip by means of the hydraulic cylinder, the magnitude of the tension force being measured'by means of load cells.
  • the cart is then moved along the length of the strip, thereby subjecting the strip to an initial bending strain distribution; then to a bending strain reversal; then to a second bending strain reversal.
  • the distance between the gage marks 1 1 is measured after the passage of the cart along the strip and this measurement is compared with the original gage length. This comparison then yields the strip elongation; that is,
  • Modulus of elasticity E, 8,520,000 lb./in.
  • Yield strain ey, 0.00312
  • Yield tension ayt, 850 lb./ in. of width
  • the diameter of the rolls on the cart was 6 inches; thus the bending strain parameter is calculated as follows:
  • percent elongation X 100 which shows a Case IA situation.
  • the initial bending strain is followed by two bending strain reversals.
  • the example result showed that with a gage length of 50 inches an elongation of 0.782 inch was produced, which corresponds to a strain of The difference is 0.015640.0140 or 0.00164 or 10.5%.
  • Modulus of elasticity E, 9,550,000 lb./in.-"- Yield strain: ey, 0.00288 Yield tension: ayt, 1105 lb./ in. of width
  • the bending strain parameter is 12 With an applied tension force of F :857 lb./in. of width,
  • the total elongation strain is obtained as before The test result showed an elongation strain of 0.0222. The difference is 0.0006 or 2.7%.
  • EXAMPLE 3 Material: Aluminum, 5052H32 Thickness: t, 0.0512 inch Yield stress: 0y 24,700 lb./in.
  • Modulus of elasticity E, 8,970,000 lb./in. Yield strain: 5y, 0.00276 Yield tension: ayt, 1263 lb./in. of width ilthfollows from Table I that we have a Case II situation.
  • a method of permanently elongating strip which comprises:
  • a method of permanently elongating strip which comprises: V (a) applying a tension force to the strip; and (b) constraining the strip while under tension to at least one bend and at least onebend reversal which n causes yielding and an incremental elongation strain that is produced between abend and a subsequent bend reversal in which the magnitude.
  • a method of permanently elongating strip which comprises:
  • a method of permanently elongating strip which comprises:
  • a method of permanently elongating strip which comprises (a) applying a tension force to the strip;
  • a method of permanently elongating strip which comprises:

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Straightening Metal Sheet-Like Bodies (AREA)
  • Non-Disconnectible Joints And Screw-Threaded Joints (AREA)
  • Helmets And Other Head Coverings (AREA)
  • Package Frames And Binding Bands (AREA)
  • Paper (AREA)
  • Tires In General (AREA)
  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
US708947A 1968-02-28 1968-02-28 Methods of permanently elongating strip Expired - Lifetime US3552175A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US70894768A 1968-02-28 1968-02-28

Publications (1)

Publication Number Publication Date
US3552175A true US3552175A (en) 1971-01-05

Family

ID=24847817

Family Applications (1)

Application Number Title Priority Date Filing Date
US708947A Expired - Lifetime US3552175A (en) 1968-02-28 1968-02-28 Methods of permanently elongating strip

Country Status (9)

Country Link
US (1) US3552175A (es)
BE (1) BE729187A (es)
DE (1) DE1909481A1 (es)
ES (1) ES364016A1 (es)
FR (1) FR2002842A1 (es)
GB (1) GB1262577A (es)
NL (1) NL6903094A (es)
NO (1) NO138241C (es)
SE (1) SE359038B (es)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3688539A (en) * 1971-05-07 1972-09-05 Harold P Hogarth Apparatus for straightening metallic fishing rod mandrels and method of using same
US4614101A (en) * 1981-12-01 1986-09-30 Herr-Voss Corporation Method of rewinding slit metal strands
US4970886A (en) * 1989-08-21 1990-11-20 Aluminum Company Of America Stretch shaping method and apparatus
FR2782463A1 (fr) * 1998-08-24 2000-02-25 Pechiney Rhenalu Procede d'amelioration de la planeite d'une tole metallique
US20100162784A1 (en) * 2008-12-31 2010-07-01 Buta John R Flattening device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2911983C2 (de) * 1979-03-27 1986-03-20 Mannesmann AG, 4000 Düsseldorf Vorrichtung zum Regeln von Anlagen zum Streckbiegerichten kontinuierlich durchlaufender Bänder

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3688539A (en) * 1971-05-07 1972-09-05 Harold P Hogarth Apparatus for straightening metallic fishing rod mandrels and method of using same
US4614101A (en) * 1981-12-01 1986-09-30 Herr-Voss Corporation Method of rewinding slit metal strands
US4970886A (en) * 1989-08-21 1990-11-20 Aluminum Company Of America Stretch shaping method and apparatus
WO1991002605A1 (en) * 1989-08-21 1991-03-07 Aluminum Company Of America Stretch shaping method and apparatus
FR2782463A1 (fr) * 1998-08-24 2000-02-25 Pechiney Rhenalu Procede d'amelioration de la planeite d'une tole metallique
US6216521B1 (en) 1998-08-24 2001-04-17 Pechiney Rhenalu Process for improving the planeness of a metal sheet
US20100162784A1 (en) * 2008-12-31 2010-07-01 Buta John R Flattening device

Also Published As

Publication number Publication date
NO138241B (no) 1978-04-24
FR2002842A1 (es) 1969-10-31
NL6903094A (es) 1969-09-01
BE729187A (es) 1969-08-01
DE1909481A1 (de) 1969-09-25
ES364016A1 (es) 1971-01-01
SE359038B (es) 1973-08-20
GB1262577A (en) 1972-02-02
NO138241C (no) 1978-08-02

Similar Documents

Publication Publication Date Title
US3253445A (en) Apparatus for rolling strip metal
RU2540286C2 (ru) Способ непрерывной правки металлических лент и устройство для непрерывной правки металлических лент
US3326026A (en) Metal sheet and strip flattening apparatus
US9604270B2 (en) Method and apparatus for stretch-leveling metal strip
US928073A (en) Method of coiling pipe.
US2004596A (en) Method and apparatus for manufacturing metal sheets and strips
US3605470A (en) Pressure assisted tension roller leveler
US3552175A (en) Methods of permanently elongating strip
US3328992A (en) Method of and apparatus for obtaining flat metallic strip
US2275095A (en) Method and means for leveling and hardening thin gauge metals
JPS5884614A (ja) ロ−ラ・レベラ
US608706A (en) Apparatus for bending form-plates for printing
US1271703A (en) Method of forming sheet-metal products.
US3270543A (en) Machine for flattening and curling of metal strip
KR101917459B1 (ko) 판재 교정 장치 및 이를 이용한 판재 제조방법
US1970911A (en) Metal working machine
US1649705A (en) Method of preventing the development of stretcher strains in metal sheets
JPH0534096B2 (es)
JPH06226349A (ja) ビルトアップ型鋼歪矯正装置
JPH0550144A (ja) テンシヨンレベラーおよび矯正方法
SU1148668A1 (ru) Рабоча клеть профилегибочного стана
CN210333837U (zh) 精密校平机
SU850683A1 (ru) Способ термической обработки движу-щЕгОС пРОКАТА
CN214441997U (zh) 带有换辊装置的多辊系带钢复合拉伸矫直机
SU1212643A1 (ru) Способ механического удалени окалины с поверхности проката