US3508978A - Process for manufacturing ski edges with l-shaped cross section - Google Patents

Process for manufacturing ski edges with l-shaped cross section Download PDF

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Publication number
US3508978A
US3508978A US625451A US3508978DA US3508978A US 3508978 A US3508978 A US 3508978A US 625451 A US625451 A US 625451A US 3508978D A US3508978D A US 3508978DA US 3508978 A US3508978 A US 3508978A
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United States
Prior art keywords
section
edge
hardness
ski
thicker
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Expired - Lifetime
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US625451A
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English (en)
Inventor
Toshimori Shuin
Takeo Sata
Masayuki Takamura
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Nippon Gakki Co Ltd
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Nippon Gakki Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/08—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling structural sections, i.e. work of special cross-section, e.g. angle steel
    • B21B1/09—L-sections
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63C—SKATES; SKIS; ROLLER SKATES; DESIGN OR LAYOUT OF COURTS, RINKS OR THE LIKE
    • A63C11/00—Accessories for skiing or snowboarding
    • A63C11/04—Accessories for skiing or snowboarding for treating skis or snowboards
    • A63C11/06—Edge-sharpeners
    • A—HUMAN NECESSITIES
    • A63—SPORTS; GAMES; AMUSEMENTS
    • A63C—SKATES; SKIS; ROLLER SKATES; DESIGN OR LAYOUT OF COURTS, RINKS OR THE LIKE
    • A63C5/00—Skis or snowboards
    • A63C5/04—Structure of the surface thereof
    • A63C5/048—Structure of the surface thereof of the edges
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/08—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling structural sections, i.e. work of special cross-section, e.g. angle steel
    • B21B1/0805—Flat bars, i.e. having a substantially rectangular cross-section
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2221/00—Treating localised areas of an article
    • C21D2221/02—Edge parts

Definitions

  • a method for manufacturing a ski edge of an L-shaped cross-section comprises a first stage for making a soft intermediate product having an L-shaped cross-section and a second stage for making a hard final product of a ski edge having an L-shaped cross section, the thicker portion being thinned by a greater rate of thickness reduction than the rate of thickness reduction at thinner portion from the intermediate product.
  • the first stage consists of several steps of cold drawing and annealing, and the second stage consists of few steps of cold drawing and heathardening, the cold drawing being carried out with a tension greater than the yield stress applied lengthwise to the material.
  • the surface of the thicker portion is hardest of the product.
  • This invention relates to a process for manufacturing a metal edge to be fitted lengthwise on the running surface of a ski at the both side ends. More particularly it relates to an edge with an L-shaped cross section, in which the portion constituting a part of the running surface of the ski has higher surface hardness and the por tion to be worked particularly for fitting to the ski body has lower hardness.
  • Materials capable of increasing hardness by heat treatment after cutting to the desired cross section would provide edges having suflicient hardness for use in skis.
  • heat treatment to increase hardness such as quenching and tempering is carried out to elongated materials with an L-shaped cross section
  • the material may have warps or twists due to strains being produced in the interior structure. Decarburization would also occur with the resultant reduction in fatigue strength.
  • the other method for obtaining a ski edge with an L-shaped cross section comprises welding two pieces of metal material together, each of which has previously been formed into a board having a rectangular cross sec tion of the desired size, in such a manner that the assembly has an L-shaped cross section.
  • This method permits the use of high hardness material for that portion of said assembly which has a surface exposed to the running surface of the ski and lower hardness material for that portion fitted to the ski body, for example, a member provided with bolt holes. Therefore this method eliminates the problems encountered in the first mentioned method. However, heat released in welding will cause the softening of high hardness material, and the resultant nonuniforrnity of local hardnesses will reduce fatigue strength.
  • austenitic stainless steel can not be used in the manufacture of a ski edge due to difiiculty of welding, although it has appreciable hardness and excellent corrosion resistance.
  • This invention provides a process for manufacturing a ski edge bearing an L-shaped cross section with the thicker section possessed of higher hardness and the thinner section of lower hardness, which comprises the steps of working an elongated metal material for plastic deformation under tension applied lengthwise in such a manner that the product has an L-shaped cross section, in which one side crosswise is thicker than the other, and the steps of further cold plastic deforming the material thus prepared similarly under tension applied lengthwise and at a higher rate of deformation for the thicker section and at a lower rate thereof for the thinner section.
  • the novel method enables edge material to be formed into the desired shape by stretching or drawing. Consequently it is free from the question of whether the material to be used is ready for cutting or welding. Since the material is worked at a greater amount of reduction in thickness for the thicker section and at a less reduction in thickness for the thinner section, it is possible to obtain a ski edge in which the thicker section, namely, one exposed to the running surface of the ski, is of higher hardness and the thinner section to be worked particularly for fitting to the ski body is of lower hardness.
  • An object of this invention is to provide a process for manufacturing a ski edge with an L-shaped cross section, in which the face of one portion exposed to the running surface of a ski is of sufficient hardness as a ski edge and the other portion has only such degree of hardness as will facilitate work required in fitting the edge to the ski body.
  • Another object of this invention is to provide a process for manufacturing a ski edge which has a level and smooth surface and is thereby given a sufliciently high fatigue strength to withstand the alternating bending stress and the alternating tensile and compression stresses transmitted to the edge by vibrations of the ski.
  • a further object of this invention is to provide a manufacturing method which permits the use of all available materials of suitable properties as a ski edge.
  • FIGS. 1 and 2 are plan views of roller dies to be used in carrying out the process according to this invention
  • FIG. 3 is a plan view of a die used in accordance with this invention.
  • FIG. 4 is a perspective view of the ski edge obtained in an example embodying this invention.
  • FIG. 5 shows curves of the relations of hardness and depth from surface of the thicker section of the edge obtained in another example embodying this invention.
  • elongated metal material with a circular or rectangular cross section is, at first, worked by rolling or drawing under tension applied lengthwise into a configuration with an L-shaped cross section, one side of which is thicker than the other.
  • the tension applied to the material is of sufficient magnitude for plastic deformation, namely, in excess of the yield point of said material under stretching stress.
  • the rod material prepared by the primary fabrication is as a whole thicker than the desired ski edge.
  • the ratio of the thicker to thinner sections should be now selected in such a manner that it exceeds that of the edge to be finally produced. For instance, when the thicker section of the final edge is desired to be 2 mm. thick and the thinner section 0.8 mm. thick (the ratio being 2.5 to l), the thinner section (to be reduced 30 percent in thickness later) of the preliminarily fabricated edge should preferably be 1.14 mm. thick, and the thicker section (to be reduced 40 percent in thickness later) should be 3.33 mm. thick, the ratio now being 2.92 to 1. When the preliminarily worked material is finally formed into the product edge, the thicker section is reduced percent more than the thinner section. This difference between the reductions in the thickness accounts for the difference in hardnesses of the thicker and thinner sections as discussed later.
  • the rate at which the original material can be deformed in the primary fabrication varies with its nature. Generally speaking, however, the upper limit for the deformation rate would be about 80 percent on the basis of the elongation rate of the material in the annealed state. Therefore, when the deformation rate reaches this upper limit, working should be stopped and started again after the material is annealed to reduce the hardness thereof. If work requiring a deformation rate higher than the aforesaid upper limit is continued, the deformation balance would be lost, resulting in the occurrence of wave formations on the thinner section and cracks in the sections which have changed in thickness. As a result, it is preferable to deform rod materials in several steps.
  • the rod which has been preliminarily Worked to have an L- shaped cross section of the desired dimensions is then annealed for softening and next cold worked by rolling or drawing under tension greater than the yield stress of the material used so as to obtain an edge of the desired size.
  • the conditions of said cold working including size of roller or die, amount of reduction in thickness of material, magnitude of and difference between tensions applied before and after the roller or die and magnitude of friction resistance of material when passing through the roller or die should be selected with the precautions taken in general rolling or drawing, in order to prevent the occurrence of cracks or warps in the material.
  • the cold working should he therefore conducted in a plurality of steps, in order to prevent cracks or warps.
  • the cold working is carried out preferably in 2 to 5 steps.
  • the cold working is carried out preferably in 2 to 5 steps.
  • edge material to the desired shape and size would result in a maximum difference of hardness between the surface and core, so as to enable the thinner section of the material to have better punching characteristics.
  • the material is often worked at the amount of reduction beyond it work limits, so that the edge thus produced will present cracks or wave formations.
  • the amount of reduction achieved by cold working should be limited in a range between 30 and 60 percent for the thicker section and between 10 and 35 percent for the thinner section, and in any case, the thicker section should be reduced, for example, 10 or more percent more than for the thinner section.
  • reduction within the aforesaid ranges will enable the thicker and thinner sections to be worked into the desired configuration by both stretching and compression for the former and mainly by stretching for the latter.
  • the surface of the thicker section namely, one exposed to the running surface of a ski
  • the thinner section i.e., one which is worked particularly for fitting to the ski body, is only hard enough to permit secondary work, such as punching, drilling or counter sinking.
  • this type of edge it is also easy to bend part or the whole of it in the longitudinal direction so as to match the ski curvature.
  • the amount of reduction by cold working may be selected suitably according to the nature of the material being used. For instance, with metal materials capable of being hardened by low temperature annealing such as austenitic stainless steel, heat treatment after primary fabrication does not bring about appreciable increase in hardness. Consequently it is necessary to select such size of the material after primary work as Will assure a great amount of reduction and to carry out further Work in such a manner that after cold Working, the material is already possessed of sufficient or approximately sufiicient hardness as a ski edge. In the case of precipitation hardenable materials such as some types of semi-austenitic stainless steel, heat treatment after cold working results in considerably increased hardness, so that cold working may be performed at a relatively small amount of reduction.
  • the rolling device suitable for rolling may comprise, as illustrated in FIG. 1, a combination of a female roller 11 having a fiat-bottom depression in the center and a male roll 12 which is provided with a stepped section so as to assure fitting into said depression.
  • a roller die is shown in FIG. 2 which comprises a combination of three fiat rollers 13, 14 and 15 arranged in such a manner that the axes are at right angles to each other and a stepped roller 16 installed in parallel to the roller 14.
  • a mold die 18 as illustrated in FIG. 3 which has the desired shape, size and L-shaped cross sectional opening 17 and the material to be cold worked is forced through said opening 17, the material can also be worked to have the desired L-shaped cross section.
  • the size of the opening of aforementioned rolling device or roller die or mold die may be selected so as to assure the thickness reduction as previously described.
  • the material may be subjected to heat treatment for further hardening. While the conditions for heat treatment should be selected suitably according to the thermal properties of the material being used, details of said heat treatment techniques are probably clear to one skilled in the art.
  • the process of this invention enables a ski edge with an L-shaped cross section to be manufactured without cutting or welding in the course of changing the cross section to the desired form.
  • This means that the process of the present invention is not disturbed in the selection of materials by such factors as machinability or weldability. Therefore the present invention has made possible the employment of such materials as have previously been excluded from use due to poor machinability or weldability, although they had good properties as ski edge material.
  • elimination of cutting is useful in improving the smoothness of an edge particularly in the longitudinal direction.
  • the one piece edge fitted to a high grade ski is saved from possible causes of breakage resulting from vibrations of the ski.
  • Example 1 The material used was a round rod 6 mm. in diameter and subjected to solution treatment which consisted of AISI 304 austenitic stainless steel, one of the low temperature annealing hardenable alloys.
  • the rod was initially worked into a configuration with a rectangular cross section by being passed through a roller die having an opening size of 4.5 mm. x 7.0 mm. under lengthwise tension applied by setting the roller front tension at 1200 kg. and the back tension at 500 kg. Then the material was further worked in three steps under the conditions indicated in Table I below.
  • the cold worked edge material had an L-shaped cross section as illustrated in FIG. 4, and indicated a hardness of 450 (Vickers hardness number H at the surface and 420 at the core of the thicker section, and 350 at the surface and 330 at the core of the thinner section.
  • the thinner section of said edge material was provided with bolt holes for fitting to the ski body, and was entirely bent to match the ski body curvature. It was maintained at a temperature of 415 C. for 2 hours and hardened by low temperature annealing. Hardness (H after hardening treatment was 500 at the surface of the thicker section.
  • AISI 301 stainless steel the same type as AISI 304, presents a high degree of hardening by cold working, it is desirable to Work the former in the same manner as described above.
  • materials such as carbon steel, alloy steel, and AISI 410 stainless steel develop a low degree of hardening by cold working, better results will be obtained if after primary working, they are subjected to patenting treatment without annealing for softening and then to cold working with a relatively high hardness maintained. After cold working, these materials also undergo secondary working and low temperature annealing.
  • Example 2 The material used was a round rod 6 mm. in diameter and subjected to solution treatment which consisted of AISI 631 stainless steel, one of the precipitation hardenable alloys. The material thus treated was worked into a form with a substantially rectangular cross section 7.0 mm. wide and 4.3 mm. thick, and further worked in three steps under the conditions shown in Table III below. Between the first and second working steps, it was maintained at a temperature of 1040 C. for 6 minutes and subjected to solution treatment by water cooling. It was pickled with an aqueous solution containing 20 percent nitric acid and 2 percent hydrofluoric acid.
  • Precipitation hardenable alloys other than A181 631 stainless steel such as A181 630, 632 and 633 stainless steel or Maraging steel can be worked by the same process as described above. However, since these materials somewhat differ in cold workability and thermal properties, it will be necessary to carry out their cold working and heat treatment under slightly varying conditions.
  • Ski edges of the same size were prepared from various materials by the process of the present invention as well as by the conventional cutting method. Measurement was made of resistance to breakage by repeated bending. All samples were fixed at one end and subjected to repeated bending of 9 mm. amplitude applied at a distance of 100 mm. from the fulcrum. The resistance to breakage is indicated in the number of these repeated bendings required to cause breakage, Table V below shows the results of measurement. It is seen from these results that the edge obtained by the process of this invention has very excellent fatigue strength.

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  • Mechanical Engineering (AREA)
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US625451A 1966-03-31 1967-03-23 Process for manufacturing ski edges with l-shaped cross section Expired - Lifetime US3508978A (en)

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JP2032966 1966-03-31

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0031399A3 (en) * 1979-07-30 1981-11-25 Consultronic (Int.)Ltd. Material for the production of stainless alpine ski edges
WO1993004742A1 (de) * 1991-08-28 1993-03-18 C.D. Wälzholz Produktions-Gesellschaft Mbh Verfahren für die herstellung einer skikante
CH682492A5 (de) * 1990-09-10 1993-09-30 Biennaform Walzprofil Ag Verfahren zur Herstellung von korrosionsfesten, hochfesten und zähen Stahlprofilen.
US5672218A (en) * 1996-06-24 1997-09-30 Slater Steels Corporation Method of straightening metal bars having extremely low levels of residual stress after straightening operations are completed

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB335076A (en) * 1929-10-04 1930-09-18 Taylor Wharton Iron & Steel Improvements in or relating to working manganese iron or steel alloys
US3116180A (en) * 1957-04-27 1963-12-31 Neuzeughammer Ambosswerk Messe Method of producing articles having a cutting edge portion and consisting of stainless chromium steel
US3281287A (en) * 1962-02-27 1966-10-25 Sandvikens Jernverks Ab Corrosion resistant edge tool and method of making the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB335076A (en) * 1929-10-04 1930-09-18 Taylor Wharton Iron & Steel Improvements in or relating to working manganese iron or steel alloys
US3116180A (en) * 1957-04-27 1963-12-31 Neuzeughammer Ambosswerk Messe Method of producing articles having a cutting edge portion and consisting of stainless chromium steel
US3281287A (en) * 1962-02-27 1966-10-25 Sandvikens Jernverks Ab Corrosion resistant edge tool and method of making the same

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0031399A3 (en) * 1979-07-30 1981-11-25 Consultronic (Int.)Ltd. Material for the production of stainless alpine ski edges
CH682492A5 (de) * 1990-09-10 1993-09-30 Biennaform Walzprofil Ag Verfahren zur Herstellung von korrosionsfesten, hochfesten und zähen Stahlprofilen.
WO1993004742A1 (de) * 1991-08-28 1993-03-18 C.D. Wälzholz Produktions-Gesellschaft Mbh Verfahren für die herstellung einer skikante
US5451276A (en) * 1991-08-28 1995-09-19 C.D. Walzholz Produktions-Gesellschaft M.B.H. Process for producing a ski edge
US5672218A (en) * 1996-06-24 1997-09-30 Slater Steels Corporation Method of straightening metal bars having extremely low levels of residual stress after straightening operations are completed

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