PL233184B1 - Metal strips and method for producing them - Google Patents

Description

Description of the invention

The invention relates to metal belts, in particular endless belts, and to a method of their manufacture.

Metal belts are used, for example, in belt presses or band saws. They consist of a metal sheet or several metal sheets which are welded together, or have been welded together. In the case where endless sheets are present, which is a preferred embodiment, the strips are transversely welded at their ends to form the endless strip. In the event that wide strips are needed, two or more strips are welded together often at their longitudinal edges so that they form a wide strip.

In the case of a strip press, here a double strip press, the upper and lower endless belts are moved at the same speed, with the endless belts extending substantially parallel or at a slight angle along the work space. A slight angle to each other may be necessary for the compactness of the pressed product, but also on the basis of the temperature-dependent change in volume.

The pressing process takes place in the working space, whereby both belts are pressed against each other and this pressure is transferred to the workpiece carried between them during its movement.

The disadvantage of these devices is that traditional tapes have a limited lifetime, especially when the tapes are affected by heat during the pressing process, and must be replaced after a certain time.

The object of the present invention was to overcome the drawbacks of the prior art and to provide a method for their production with which the user is able to obtain a long service life.

This is achieved by means of metal strips and the manufacturing method according to the claims.

The inventive method for producing metal strips comprises the steps of:

- delivery of a metal strip material with a pre-set thickness, width and length,

- optional: joining at least two metal strip materials at the longitudinal edges to form a wider strip material by welding (longitudinal welding),

- heating up to a pre-glow temperature between 90 ° C and 150 ° C,

- uniform heating immediately thereafter from the pre-glow temperature to a temperature between 5 ° C and 60 ° C, especially a temperature between 20 ° C and 40 ° C, below the set target temperature over a period between 2 h-4 h, target temperature is between 450 ° C and 700 ° C,

- immediately followed by, uniform heating to the target temperature within 0,1 h-1 h,

- maintaining the target temperature for the period of 0.5 h - 2.5 h ("soaking temperature"),

- cooling down to the afterburning temperature between 200 ° C and 400 ° C in the period between 0.5 h-2.5 h,

- the immediate subsequent cooling from the after-burning temperature to room temperature,

- optional: joining the ends of the heat-treated strip material to form an endless strip by welding ("transverse welding).

Preferably, the preglow temperature is between 100 ° C and 140 ° C, in particular between 110 ° C and 130 ° C, with a temperature of 120 ° C (+/- 2 ° C) being particularly preferred. The time over which this occurs need not necessarily be determined, but has proved to be advantageous when the heating time is between 0.2 h and 1 h.

Preferably, heating from the preglow temperature to a temperature below the set target temperature takes place over a period of 2.5 h to 4 h, in particular over a period of 3 h (+/- 10 min).

Preferably, the heating to the target temperature occurs over a period of 0.5 h (+/- 5 min).

Preferably, the target temperature is maintained between 1 h and 2 h, in particular 1.5 h (+/- 10 min).

Preferably, the afterburning temperature is between 250 ° C and 350 ° C, in particular 300 ° C (+/- 10 ° C).

PL 233 184 B1

Preferably, the cooling to the post-combustion temperature takes place over a period of between 1 h-2 h, especially 1.5 h (+/- 10 min).

The target temperature depends on the web material used and is preferably between 450 ° C and 600 ° C. In a preferred embodiment, the target temperature lies on the "descending branch" of the heat treatment curve, that is to say in the range in which the strength of the heat treated strip material has a negative gradient as a function of the annealing temperature.

The heat treatment curve shows the strength function of the heat-treated strip material (Y axis) as a function of the annealing temperature (X axis). In the case of a low soaking temperature, this curve increases with increasing temperature, reaches a maximum and descends again with increasing temperatures (negative gradient).

Preferably, the annealing temperature is chosen such that it is higher than the maximum temperature of the curve, or so selected that the function has a negative derivative therein with respect to the temperature.

This has the advantage that the finished tape, if it is to be subjected to high temperatures in use, becomes softer and therefore more tough. Thereby, the likelihood of failure in operation due to the brittleness involved is minimized.

The% by weight is given below, with the% sign.

Metal strips according to the invention have been produced by the method according to the invention, and in addition to Fe, which forms a residual mass and the inevitable impurities, contain:

0.03% -0.2% C,

14% -18% Cr,

4% -6% Ni,

0% -3.5% Cu,

0% -0.5% Ti,

0% -0.8% Si i

0% -1% Mn.

Preferably, the hardness [HV 10] of the base material (before heat treatment) is between 300 and 400. Here and below, the hardness is given on the Vickers scale.

Preferably, the hardness [HV 10] of the heat treated strip is between 400 and 500.

Preferably, the hardness [HV 10] of the heat treated strip, compared to the base material, has increased between 100 and 200.

Preferably, the tensile strength (Rm) of the base material (before heat treatment) is between 1000 N / mm ² and 1450 N / mm ² , especially between 1050 N / mm ² and 1200 N / mm ² .

Preferably, the tensile strength of the heat treated strip is between 1300 N / mm ² and 1700 N / mm ² , in particular between 1450 N / mm ² and 1600 N / mm ² .

Preferably, the tensile strength of the heat treated strip has increased, compared to the base material, between 350 N / mm ² and 500 N / mm ² , especially between 380 N / mm ² and 450 N / mm ² .

Preferably, the 0.2% physical yield strength (Rp - 0.2) of the base material (before heat treatment) is between 900 N / mm ² and 1400 N / mm ² , especially between 950 N / mm ² and 1100 N / mm ² .

Preferably, the physical yield strength of 0.2% of the heat treated strip is between 1300 N / mm ² and 1700 N / mm ² , in particular between 1400 N / mm ² and 1550 N / mm ² .

Preferably, the physical yield strength of 0.2% of the heat treated strip, compared to the base material, has increased between 350 N / mm ² and 500 N / mm ² , especially between 380 N / mm ² and 430 N / mm ² .

Preferably, the alternating fatigue strength of the base material (before heat treatment) is between 400 N / mm ² and 600 N / mm ² , in particular between 450 N / mm ² and 550 N / mm ² .

Preferably, the alternating load bending strength of the heat treated strip is between 600 N / mm ² and 800 N / mm ² , in particular between 630 N / mm ² and 720 N / mm ² .

Preferably, the alternating load bending strength of the heat treated strip has increased compared to the base material between 100 N / mm ² and 300 N / mm ² , especially between 180 N / mm ² and 220 N / mm ² .

PL 233 184 B1

Preferably, the tensile strength (Rm) of the cross seam of the base material (before heat treatment) is between 800 N / mm ² and 1200 N / mm ² , especially between 900 N / mm ² and 1100 N / mm ² .

Preferably, the tensile strength of the cross-seam of the heat treated strip is between 1000 N / mm ² and 1300 N / mm ² , in particular between 1180 N / mm ² and 1250 N / mm ² .

Preferably, the tensile strength of the cross seam of the heat treated strip, compared to the cross seam in the base material, has increased between 20 N / mm ² and 150 N / mm ² , especially between 30 N / mm ² and 110 N / mm ² .

Preferably, the tensile strength of the longitudinal seam of the heat treated strip is between 1200 N / mm ² and 1700 N / mm ² , especially between 1310 N / mm ² and 1550 N / mm ² .

Hardness, tensile strength, physical yield point and bending fatigue strength under alternating load of the base material, when only heat-treated material is present, can be determined simply by establishing the chemical composition from specialist literature or by subsequent production of the base material without heat treatment.

Metal strips according to the invention have been produced by the method according to the invention and, in addition to Fe, which forms the residual mass, and the inevitable impurities, contain

0.01% -0.2% C,

12% -17% Cr,

4% -8% Ni,

0% -3.5% Cu,

0% -0.5% Ti,

0% -1.8% Si i

0% -2% Mn.

Optionally, the strips contain 0.6% -1.4% Mn and 0.15% -0.35% Si.

Preferably, the hardness [HV 10] of the base material (before heat treatment) is between 300 and 500. Here and below, the hardness is given on the Vickers scale.

Preferably, the hardness [HV 10] of the heat treated strip is between 400 and 600.

Preferably, the hardness [HV 10] of the heat treated strip, compared to the base material, has increased between 100 and 200.

Preferably, the tensile strength (Rm) of the base material (before heat treatment) is between 1000 N / mm ² and 1450 N / mm ² , especially between 1200 N / mm ² and 1420 N / mm ² .

Preferably, the tensile strength of the heat treated strip has increased, compared to the base material, between 350 N / mm ² and 500 N / mm ² , especially between 380 N / mm ² and 450 N / mm ² .

Preferably, the 0.2% physical yield strength (Rp - 0.2) of the base material (before heat treatment) is between 900 N / mm ² and 1400 N / mm ² , especially between 950 N / mm ² and 1350 N / mm ² .

Preferably, the physical yield strength of 0.2% of the heat treated strip, compared to the base material, has increased between 350 N / mm ² and 500 N / mm ² , especially between 380 N / mm ² and 430 N / mm ² .

Preferably, the alternating fatigue strength of the base material (before heat treatment) is between 400 N / mm ² and 600 N / mm ² , in particular between 450 N / mm ² and 550 N / mm ² .

Preferably, the alternating load bending strength of the heat treated strip has increased compared to the base material between 100 N / mm ² and 300 N / mm ² , especially between 180 N / mm ² and 220 N / mm ² .

Preferably, the tensile strength (Rm) of the cross seam of the base material (before heat treatment) is between 900 N / mm ² and 1,200 N / mm ² , in particular between 950 N / mm ² and 1150 N / mm ² .

Preferably, the tensile strength of the cross seam of the heat treated strip, compared to the cross seam in the base material, has increased between 20 N / mm ² and 150 N / mm ² , especially between 30 N / mm ² and 110 N / mm ² .

Hardness, tensile strength, physical yield point and bending fatigue strength under alternating load of the base material, when only heat-treated material is present, can be determined simply after determination

The chemical composition is based on specialist literature or by subsequent preparation of the base material, without heat treatment.

The heat treatment of the strips is preferably carried out in an oven. In this case, the strip is preferably wound into a coil. During the winding of the web, a metal foil, for example a copper foil, is additionally rolled up together with the strip material. This has the advantage that the layers of the web of strip material do not scratch each other.

According to a preferred embodiment, the belts have a length between 20 m and 190 m, preferably between 40 m and 170 m. In the case of endless belts, this is understood to mean the length of the circulation along the complete belt. This is an advantageous belt length for wooden and transport belts.

In the case where the finished tapes are to be in the form of endless tapes, in a preferred embodiment the heat treatment takes place prior to welding into the form of endless tapes.

In the event that two or more strips are to be welded longitudinally to form a wide strip, in a preferred embodiment the heat treatment preferably follows welding. According to a further preferred embodiment, the heat treatment takes place prior to welding.

Examples of preferred embodiments of the tapes according to the invention are presented below.

P r z k ł a d 1

The metal strip material consists of at most 0.09% C, 15% Cr, 7% Ni, 0.7% Cu, 0.4% Ti and a remainder of Fe. Its tensile strength is 1150 N / mm 2 and its hardness [HV 10] is 360.

After heat treatment according to the method of the invention, at a soaking temperature of 540 ° C-570 ° C, its tensile strength is 1550 N / mm 2, and its hardness [HV 10] 480.

P r z k ł a d 2

The metal strip material consists of 0.03% C, 14.5% Cr, 4.5% Ni, 3.3% Cu and the remainder of Fe. Its tensile strength is 1050 N / mm ² and its hardness [HV 10] is 330.

After heat treatment according to the method according to the invention, at an annealing temperature of 470 ° C-520 ° C, its tensile strength is 1450 N / mm ² and its hardness [HV 10] 460.

In the examples, it can be clearly recognized that the heat treatment increases the tensile strength and hardness of the materials. This increase takes place by separating the precipitation hardening element in each case from the thermodynamically dissolved state. The separated elements create phases that prevent shifts and thus increase hardness and strength.

In Examples 1 and 2, as a rule, one element is separated from the crystalline composite during the heat treatment, without leaving the strip material (precipitation hardening element). In this way, the respective material is chemically still present in the material, but is no longer part of the basic microstructure. The materials mentioned in Examples 1 and 2 are martensitic materials. In Example 1, Ti is an precipitation hardening alloying element, in Example 2, Cu is an precipitation hardening alloying element.

The embodiments describe the possible variants of the embodiment, it should be noted here that the invention is not limited to the specially shown embodiments, but rather that various combinations of the various embodiments are possible with each other and this possibility of variation thanks to a pattern for technical operation through the present invention. depends on the skill of a specialist active in this field of technology.

Moreover, also the individual features or combinations of features shown and described in the various embodiments are self-contained, inventive or in accordance with the invention.

The task underlying the stand-alone solutions according to the invention can be taken from the description.

All data on value ranges in the present description should be understood to include any and all partial ranges, for example the given 0% to 1% should be understood to include all partial ranges together, starting from the lower limit of 0% (exclude) and an upper limit of 1%, i.e. all sub-ranges shall start at a lower limit of 0% or more and end with an upper limit of 1% or less, for example 0% to 0.7%, or 0, 1% to 1%, or 0.5% to 0.9%.

First of all, the individual embodiments form the subject of the stand-alone solutions of the invention.

Claims (9)

Patent claims 1. A method of producing metal strips, comprising the steps of: - delivery of a metal strip material with a pre-set thickness, width and length, - heating up to a pre-glow temperature between 90 ° C and 150 ° C, - immediately followed by uniform heating from the pre-glow temperature to a temperature between 5 ° C and 60 ° C, below the set target temperature for a period between 2 h-4 h, the target temperature being between 450 ° C and 700 ° C, - immediately followed by, uniform heating to the target temperature within 0,1 h-1 h, - maintaining the target temperature for the period of 0.5 h-2.5 h ("soaking temperature"), - cooling down to the afterburning temperature between 200 ° C and 400 ° C in the period between 0.5 h-2.5 h, - immediately followed by cooling from the after-burning temperature to room temperature. 2. The method according to p. The process of claim 1, characterized in that at least two metal strip materials are joined together by welding at the longitudinal edges to form a wider strip material (longitudinal welding), in particular before heat treatment, and / or that the ends of the heat treated strip material are joined together in the form of an endless strip ("transverse welding), especially after heat treatment. 3. The method according to p. The process of claim 1-2, wherein during heating, it is heated from the preglow temperature to a temperature between 20 ° C and 40 ° C below the target temperature. 4. The method according to p. The process of claim 1, wherein the target temperature is between 450 ° C and 600 ° C and / or that the target temperature lies on the descending branch of the heat treatment curve to the extent that the strength function of the heat-treated strip material as a function of the annealing temperature has a negative gradient. 5. The method according to p. A process according to any of the claims 1 to 5, characterized in that the heat treatment of the strips is carried out in an oven, the strip being preferably wound into a coil during the heat treatment. 6. A metal strip which has been produced by the method of claim 1 A composition according to any of the claims 1-6, characterized in that, in addition to Fe, which forms the residual mass and contains the unavoidable impurities, it additionally contains 0.5% Ti, 0% -1.8% Si and 0% -2% Mn. 7. Metal strip according to claim 1 6. The strip according to claim 6, characterized in that the strip has a length between 20 m and 190 m, preferably between 40 m and 170 m. 8. The metal strip according to claim 1 6 or 7, characterized in that the base material (before heat treatment) has a hardness [HV 10] between 300 and 500 and / or a tensile strength (Rm) between 1000 N / mm ² and 1450 N / mm ² and / or physical 0.2% yield strength (Rp - 0.2) between 900 N / mm ² and 1400 N / mm ² and / or bending fatigue strength with alternating load between 400 N / mm ² and 600 N / mm ² and / or the tensile strength (Rm) of the transverse seam between 800 N / mm ² and 1,200 N / mm ² , and / or the tensile strength of the longitudinal seam between 1,200 N / mm ² and 1,700 N / mm ² . 9. The metal strip according to claim 1 7 to 8, characterized in that the hardness [HV 10] has increased between 100 and 200 and / or the tensile strength between 350 N / mm ² and 500 N / mm with regard to the heat-treated strip compared to the base material ² and / or 0.2% physical yield strength between 350 N / mm and 500 N / mm ² and / or bending fatigue strength with alternating load between 100 N / mm ² and 300 N / mm ² and / or tensile strength transverse weld between 20 N / mm ² and 150 N / mm ² .