EP0601024B1 - Process for producing a ski edge - Google Patents

Abstract

PCT No. PCT/EP92/01958 Sec. 371 Date May 10, 1994 Sec. 102(e) Date May 10, 1994 PCT Filed Aug. 26, 1992 PCT Pub. No. WO93/04742 PCT Pub. Date Mar. 18, 1993.A process is disclosed for producing a ski edge made of quenched and subsequently tempered steel having a head (2) that comprises the running surface and a flank (4) that projects into the body of the ski. The profiled edge (1) is at first rolled, then quenched and subsequently tempered over its whole cross-section. Afterwards, the flank (4) is partially tempered and provided in a separate operation with punched out openings. In order to obtain with this process a totally straight ski edge, the deviation in Rockwell hardness, seen in the direction of the cross-section and length of the profiled edge is set at less than 2 DEG HRC during quenching and subsequent tempering of the whole profiled edge. The warming-up temperature and duration during partial warming-up of the edge are the same over the whole length of the profile edge and the profiled edge is subjected to a constant bending strain before being punched.

Description

• a) Walzen oder Ziehen des Kantenprofiles;
• b) Vergüten des gesamten Kantenprofiles durch Erwärmen auf die Härtetemperatur und anschließendes Anlassen;
• c) partielles Erwärmen der Flanke auf eine Temperatur größer als Anlaßtemperatur unter gleichzeitiger Kühlung des Kopfes;
• d) Stanzen der Ausnehmungen und/oder Öffnungen in der Flanke.

The invention relates to a method for producing a ski edge made from tempered steel, which has a head which has the tread and a flank projecting into the body of the ski, which is thinner than the head and has a length of a plurality of punched recesses and / or openings is provided, with the successive process steps listed below:

• a) rolling or pulling the edge profile;
• b) tempering the entire edge profile by heating to the hardening temperature and subsequent tempering;
• c) partial heating of the flank to a temperature greater than the tempering temperature with simultaneous cooling of the head;
• d) punching the recesses and / or openings in the flank.

A method of the type mentioned is known from DE-OS 22 04 270. Ski edges produced according to this process have the advantage on the one hand that the head is very hard over the entire cross section by forming a martensitic structure, so that a long life of the ski edge without resharpening results. On the other hand, the flank is returned to an essentially pearlitic structure by the partial heating, so that this flank is relatively soft and ductile and can accordingly be machined by punching with little tool wear.

Although the previously known method offers the advantages discussed above, it has not been possible to introduce it in practice. This is essentially due to the fact that the ski edge produced in this way does not run in a straight line, but is curved differently in the main plane of extension. Attempts to avoid these unavoidable curvatures - also called saber deviations - or to reverse them by subsequent bending deformation, have failed in the past due to the fact that the radii of curvature occurring differ greatly over the length of the edge profile, so that it is practically impossible to Bending device to set the correct bending deformation in each case.

It is an object of the invention to design the method of the type mentioned at the outset such that the ski edge produced thereafter runs in a completely straight line.

To achieve this object, the invention proposes starting from the method of the type mentioned that when the entire edge profile is tempered, the deviation in the Rockwell hardness across the cross section and the length of the edge profile is set to less than 2 ° HRC, that the heating temperature and the heating duration during the partial heating of the flank is kept constant over the length of the edge profile and that the edge profile is subjected to a constant bending deformation after the partial heating and before punching, in which the flank is stretched by a constant amount.

The invention is based on the knowledge that the inevitable saber deviations are essentially the result of volume changes which occur when the martensitic structure changes to a ferritic / pearlitic structure. The transition from martensitic to ferritic / pearlitic microstructure of a carbon steel results in a volume contraction, which in the present case - since post-treatment on the edge profile only takes place on one side in the area of the flank - inevitably leads to strong saber formation. If you now ensure by means of a corresponding heat treatment that, on the one hand, the deviations in the Rockwell hardness - that is, when tempering the entire edge profile. H. in the formation of martensite - seen over the cross-section and the length of the edge profile are low and on the other hand the heating temperature and the heating duration, d. H. Perlite formation - when the flank is partially heated over the length of the edge profile is largely constant, there is a uniform saber deviation over the length of the edge profile, which can be easily reversed in a subsequent bending deformation by uniformly stretching the flank of the edge profile.

The very uniform formation of martensite in the edge profile before partial heating, which is required according to the invention, can be achieved, for example, by performing a multi-stage continuous tempering when tempering the entire edge profile, in which the edge profile is first ruggedly heated to a temperature just above the martensite in a continuous metal bath. Starting temperature (Ms) is cooled, then a structural transformation of the austenitic structure formed during the cooling of the rug into the martensitic structure slow cooling is carried out under an air shower and then a tempering treatment is carried out under protective gas. In contrast to the oil quenching conventionally used, the explained multi-stage coating leads to a very uniform martensitic structure, which is largely free of internal stresses. The metal bath quenching and tempering under protective gas have the effect that oxidation phenomena on the profile surfaces are avoided. The latter is important for the subsequent uniform heating of the flank of the profile, which would be hindered by oxidation layers.

The abraded cooling mentioned above is expediently carried out in a lead bismuth continuous bath with a constant temperature of in particular 350 ° C.

A particularly good quality ski edge that can be stamped with low tool wear results if the entire edge profile is tempered to a Rockwell hardness of 50 ° - 60 ° HRC and the hardness of the flank is reduced to 30 ° - 40 ° HRC by partial heating.

Fig. 1:

einen Querschnitt durch ein gestanztes Kantenprofil in einer ersten Ausführungsform;

Fig. 2:

eine Draufsicht zu Fig. 1;

Fig. 3:

einen Querschnitt durch ein gestanztes Kantenprofil in einer zweiten Ausführungsform;

Fig. 4:

eine Draufsicht zu Fig. 3;

Fig. 5:

schematisch das Verfahren gemäß der Erfindung in seinem Ablauf;

Fig. 6:

schematisch die zusätzliche Durchlauf-Anlaßvorrichtung quer zur Durchlaufrichtung.

An embodiment of the invention is explained below with reference to the drawings. Show it:

Fig. 1:

a cross section through a stamped edge profile in a first embodiment;

Fig. 2:

a plan view of Fig. 1;

Fig. 3:

a cross section through a stamped edge profile in a second embodiment;

Fig. 4:

a plan view of Fig. 3;

Fig. 5:

schematically the process according to the invention in its sequence;

Fig. 6:

schematically the additional flow starting device transverse to the direction of flow.

1 to 4, the edge profile is designated in its entirety with reference number 1. It consists of a head 2, which has the tread 3 and a flank 4, which is thinner than the head 2 and serves to anchor the edge profile 1 in the body of the ski.

As can be seen from FIGS. 2 and 4, the flank 4 is provided with punched recesses 5 (FIG. 2) or openings 6 (FIG. 4) which, when the edge profile 1 is fastened in the body of the ski, for better toothing and anchoring to serve. In a departure from the exemplary embodiments shown, the recesses 5 and the openings 6 can also have a different shape.

The entire edge profile 1 consists of a hardenable steel, which is hardened by the method according to the invention in the area of the head 2 over its entire volume to a high hardness, for example a Rockwell hardness of 50 ° -60 ° HRC, while the flank 4 is reduced to, for example, 30 ° -40 ° HRC by additional partial tempering.

The device for carrying out the method according to the invention shown in FIGS. 5 and 6 consists of a profile rolling mill 7 or a corresponding profile drawing system, in which the continuous edge profile 1 receives the correct profile shape. The edge profile 1 then passes through a tempering system 8, in which the edge profile 1 is tempered uniformly over its entire cross-section by heating to the supercritical temperature and then quenching and tempering, to a relatively high degree Hardness that corresponds to the final hardness of the head 2. Quenching in the tempering system 8 takes place in a continuous metal bath which contains a liquid lead-bismuth melt at a constant temperature, preferably about 350 ° C. This temperature is just above the martensite start temperature (M _s ). During the abrupt cooling process, an essentially austenitic structure is formed in the edge profile 4. The edge profile is then slowly cooled under an air shower, the austenitic structure previously formed during the rugged cooling process being converted into a largely homogeneous martensitic structure. The edge profile 1 is then left under a protective gas to a relatively low tempering temperature in order to set the desired material properties exactly. The multi-stage coating explained above results in a largely uniform hardness over the cross-section and over the length of the edge profile 1. The deviations in the Rockwell hardness over the cross-section and the length of the edge profile 1 are at most 2 ° HRC.

Thereafter, the edge profile 1, which has been hardened uniformly over its entire volume, passes through a continuous system 9 for the additional partial tempering of the flank 4. The amount of heat introduced in this process is regulated constantly in order to obtain a uniform bend over the length of the edge profile 1. Only then is it possible to precisely align the material after partial tempering.

The continuous system shown in FIG. 6 for the additional partial starting of the flank 4 has two, for example, water-cooled cooling boxes 10a and 10b, which leave a passage opening 11 between them. whose cross-sectional shape is adapted to the cross-sectional shape of the head 2. The cooling surfaces of the passage opening 11 lie against the head 2 from three sides and leave the flank 4 free, ie uncooled.

A heating device 12 is assigned to the section of the flank 4 which remains uncooled. This heating device 12 can be a precisely controllable gas burner, an induction coil or a radiant heater, in particular a laser heater. Conductive heating is also possible, for example heating in a suitably shielded metal bath or by means of a radiator which is brought into contact with the flank 4 of the edge profile 1.

As can also be seen from FIG. 6, the passage opening 11 is shaped such that the transition region 4a between the head 2 and the flank 4 is still cooled. This results in a transition region 4a between the head 2 which remains hard and the additionally tempered flank 4, the hardness of which lies between that of the head 2 and the flank 4. The throughput speed v of the edge profile 1 and the heat supply Q through the heating device 12 are coordinated with one another in such a way that the heating temperature and the heating duration - and thus the formation of a pearlitic structure - in the flank 4 - are kept constant over the length of the edge profile 1.

The continuous system 9 for the additional partial starting of the flank 4 is also followed by a device 13 for slow and controlled cooling of the flank 4.

The finished heat-treated edge profile 1 is subsequently subjected to a bending deformation in a bending device 14, in which the flank 4 is stretched by a uniform amount. As a result of this bending deformation, the uniform curvature of the edge profile 1 which forms when the inner edge part is partially heated is reversed.

Finally, the finished heat-treated and directed edge profile 1 is provided with the recesses 5 and / or openings 6 in a stamping unit 15. This process takes place either immediately after the heat treatment or, if appropriate, at another manufacturing facility, for example at the manufacturing facility of the ski manufacturer. Since the flank 4 to be provided with the recesses 5 or openings 6 has only a low hardness, the tool wear in this punching process is very low.

The system components shown schematically in FIG. 5 can be installed in a production facility in a continuous production line. However, they can also be used at different production sites, as is symbolized in FIG. 5 by the parallel dividing lines in the flow arrows.

Claims (4)

1. A process for the production of a ski edge of heat-treated steel, which has a head having the running surface and a flank portion which projects into the body of the ski and which is thinner than the head and which is provided over its length with a plurality of stamped recesses and/or openings, comprising the successive process steps set out below:

   a) rolling or drawing the edge profile;

   b) heat-treating the entire edge profile by heating to the hardening temperature and then tempering;

   c) partially heating the flank portion to a temperature higher than the tempering temperature with simultaneous cooling of the head; and

   d) stamping the recesses and openings in the flank portion,

      characterised in that in the operation of heat-treating the entire edge profile (1) the deviation in the Rockwell hardness as viewed over the cross-section and the length of the edge profile (1) is set to less than 2°HRC, that the heating temperature and the heating duration are kept constant in the operation of partially heating the flank portion (4) over the length of the edge profile (1) and that the edge profile (1) is subjected after the partial heating operation and prior to the stamping operation to a uniform bending deformation operation in which the flank portion (4) is stretched by a uniform amount.
2. A process according to claim 1 characterised in that in the operation of heat-treating the entire edge profile (1) a multi-stage continuous-run heat-treatment is effected in which the edge profile (1) is firstly cooled abruptly in a through-run metal bath to a temperature just above the martensite starting temperature (M_s), then an operation is effected for transformation of the austenitic structure formed in the abrupt cooling operation into the martensitic structure with slow cooling under an air shower and finally a tempering treatment is effected under a shielding gas.
3. A process according to claims 1 and 2 characterised in that the abrupt cooling operation is effected in a through-run lead-bismuth bath (8a) at a uniform temperature of in particular 350°C.
4. A process according to one of claims 1 to 3 characterised in that the heat-treatment of the entire edge profile (1) is to a Rockwell hardness of 50° - 60°HRC and that the hardness of the flank portion (4) is reduced by partial heating to 30° - 40°HRC.

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