Method for determining the stamping quality of profiled bar material

Abstract

A method for determining the stamping quality of profiled bar includes steps of: a) upstream of the rolling stand performing shaping, the initial speed V.sub.A of the starting product is determined and the initial diameter D.sub.A or initial cross-sectional area F.sub.A are determined contactlessly. b) After the rolling stand, the final speed V.sub.E of the end product is measured and the diameter D.sub.E or area F.sub.E of a virtual enveloping shell for the end product is determined contactlessly. c) The diameter D.sub.N of a virtual, round end product is determined contactlessly as D.sub.N=square root of (D.sub.A.sup.2*V.sub.A/V.sub.E) and/or the average cross-sectional area F.sub.NE of the end product (2) is determined contactlessly as F.sub.NE=F.sub.A*V.sub.A/V.sub.E. d1) The characteristic stamping variable PKG is calculated, and the characteristic stamping variable PKG is compared with a pre-set setpoint value PKG.sub.set. A device for carrying out the method is also provided.

Claims

1. A method for determining a stamping quality of bar material having a ribbed or recessed profile, which is advanced in a rolling train that includes a rolling stand (3) that carries out a shaping process by means of stamping rollers, the method comprising: a) upstream of the rolling stand (3), an initial speed V.sub.A of a starting product (1) to be shaped by the rolling stand (3) is determined and, an initial diameter D.sub.A or an initial cross-sectional area F.sub.A are determined contactlessly, b) after the rolling stand (3), a final speed V.sub.E of an end product (2) is measured and a diameter D.sub.E or a cross-sectional area F.sub.E of a virtual enveloping shell for the end product (2) is/are determined contactlessly, the diameter D.sub.E or cross-sectional area F.sub.E of the virtual enveloping shell being a maximum or average diameter or cross-sectional area of the ribbed or recessed profile c) a diameter D.sub.N of a virtual, round end product is determined contactlessly as
D.sub.N=square root of (D.sub.A.sup.2V.sub.A/V.sub.E) or an average cross-sectional area F.sub.NE of the end product (2) is determined contactlessly as
F.sub.NE=F.sub.AV.sub.A/V.sub.E, d1) a characteristic stamping variable PKG is calculated on a basis of D.sub.E and D.sub.N or on a basis of F.sub.E and F.sub.NE, wherein the characteristic stamping variable PKG is calculated as a difference between or a ratio of D.sub.E and D.sub.N or as the difference between, or the ratio of, F.sub.E and F.sub.NE, or d2) values determined and calculated in steps a), b) and c) are used for calculating variables derived from them, the derived variables being: i) an initial volume or an initial weight per unit of length of the starting product (1), ii) a volume or a weight of the virtual enveloping shell per unit of length iii) a volume of the end product (2) per unit of length or a weight of this volume of the end product (2), and iv) the characteristic stamping variable PKG is calculated as the difference between or the ratio of the volume of the virtual enveloping shell per unit of length and the volume of the end product (2) per unit of length, and/or the difference between the or the ratio of the weight of the virtual enveloping shell per unit of length and the weight of the end product (2) per unit of length, and e) the characteristic stamping variable PKG is compared with a pre-set setpoint value PKG.sub.set, wherein PKG.sub.set represents a desired stamping quality.

2. The method according to claim 1, wherein the diameter D.sub.A or D.sub.E or a number of diameters D.sub.A or D.sub.E of the starting product (1) and of the virtual enveloping shell of the end product (2) is/are measured.

3. The method according to claim 2, the wherein a greatest measured diameter D.sub.E of the virtual enveloping shell of the end product (2) is used for the calculation of the characteristic stamping variable PKG.

4. The method according to claim 2, wherein the weight per meter of the starting product (1) is used for the calculation of the characteristic stamping variable PKG as the initial weight per unit of length of the starting product (1), the weight per meter of the volume of the virtual enveloping shell is used for the calculation of the characteristic stamping variable PKG as the weight per unit of length of the volume of the virtual enveloping shell and the weight per meter of the end product (2) is used for the calculation of the characteristic stamping variable PKG as the weight per unit of length of the end product (2).

5. The method according to claim 2, wherein one or more of the contactless determinations is/are performed optically.

6. The method according to claim 2, wherein the rolling train or the rolling stand (3) is controlled with the aid of the data determined in step e).

7. The method according to claim 2, wherein the diameters D.sub.A or D.sub.E at different angular positions are measured.

8. The method according to claim 7, wherein a greatest measured diameter D.sub.E of the virtual enveloping shell of the end product (2) is used for the calculation of the characteristic stamping variable PKG.

9. The method according to claim 7, wherein the weight per meter of the starting product (1) is used for the calculation of the characteristic stamping variable PKG as the initial weight per unit of length of the starting product (1), the weight per meter of the volume of the virtual enveloping shell is used for the calculation of the characteristic stamping variable PKG as the weight per unit of length of the volume of the virtual enveloping shell and the weight per meter of the end product (2) is used for the calculation of the characteristic stamping variable PKG as the weight per unit of length of the end product (2).

10. The method according to claim 7, wherein one or more of the contactless determinations is/are performed optically.

11. The method according to claim 7, wherein the rolling train or the rolling stand (3) is controlled with the aid of the data determined in step e).

12. The method according to claim 1, wherein a greatest measured diameter D.sub.E of the virtual enveloping shell of the end product (2) is used for the calculation of the characteristic stamping variable PKG.

13. The method according to claim 12, wherein the weight per meter of the starting product (1) is used for the calculation of the characteristic stamping variable PKG as the initial weight per unit of length of the starting product (1), the weight per meter of the volume of the virtual enveloping shell is used for the calculation of the characteristic stamping variable PKG as the weight per unit of length of the volume of the virtual enveloping shell and the weight per meter of the end product (2) is used for the calculation of the characteristic stamina variable PKG as the weight per unit of length of the end product (2).

14. The method according to claim 12, wherein one or more of the contactless determinations is/are performed optically.

15. The method according to claim 12, wherein the rolling train or the rolling stand (3) is controlled with the aid of the data determined in step e).

16. The method according to claim 1, wherein the weight per meter of the starting product (1) is used for the calculation of the characteristic stamping variable PKG as the initial weight per unit of length of the starting product (1), the weight per meter of the volume of the virtual enveloping shell is used for the calculation of the characteristic stamping variable PKG as the weight per unit of length of the volume of the virtual enveloping shell and the weight per meter of the end product (2) is used for the calculation of the characteristic stamping variable PKG as the weight per unit of length of the end product (2).

17. The method according to claim 16, wherein one or more of the contactless determinations is/are performed optically.

18. The method according to claim 16, wherein the rolling train or the rolling stand (3) is controlled with the aid of the data determined in step e).

19. The method according to claim 16, wherein the weight of the end product (2) is calculated as F.sub.NEpunit of length.

20. The method according to claim 19, wherein one or more of the contactless determinations is/are performed optically.

21. The method according to claim 19, wherein the rolling train or the rolling stand (3) is controlled with the aid of the data determined in step e).

22. The method according to claim 1, wherein one or more of the contactless determinations is/are performed optically.

23. The method according to claim 22, wherein the rolling train or the rolling stand (3) is controlled with the aid of the data determined in step e).

24. The method according to claim 1, wherein the rolling train or the rolling stand (3) is controlled with the aid of data determined in step e).

Description

(1) The invention is explained in more detail on the basis of the accompanying drawings, in which:

(2) FIG. 1 shows a side view and a cross-sectional view of a rebar ribbed on two sides, with a raised ribbing,

(3) FIG. 2 shows a side view and a cross-sectional view of a rebar profiled on three sides, with a deep ribbing,

(4) FIG. 3 shows a typical rolling train in a schematic representation with the measuring devices required,

(5) FIG. 4 shows a graphic representation of the method according to the invention,

(6) FIG. 5 shows a schematic representation of a diameter measuring device, the diameter determination being based on a shadow method and a total of three diameters being determined at different angular positions of the end product,

(7) FIG. 6 shows the cross-sectional form for a three-sided rebar with raised ribbing and

(8) FIG. 7 shows a perspective representation of a rebar ribbed on two sides, with raised ribbing oriented at irregular angular positions with respect to the bar axis, and the schematically depicted enveloping shell diameter and cross section.

(9) The profiled concrete reinforcing bars shown in FIGS. 1 and 2 are in the case of FIG. 1 a rebar with raised ribbing that is ribbed on two sides and in the case of FIG. 2 a corresponding rebar with deep ribbing that is ribbed on three sides. This profiled bar material is produced continuously and obtained after the rolling stand performing the shaping and is then cut to the desired length. All of this is known.

(10) As can be seen from FIG. 3, the starting product 1, which is bar-shaped bar material with a round cross section, is shaped in the rolling stand 3 with the aid of the rollers 31 to form a profiled bar material or end product 2. This end product may, for example, be the end product 2 that is shown in FIG. 7.

(11) In a manner corresponding to FIGS. 3 and 4, before entering the rolling stand 3, the speed V.sub.A of the starting product 1 fed to the rolling stand 3 is determined with the aid of a contactlessly operating speed measuring device 12.

(12) Furthermore, the diameter D.sub.A of the starting product 1 is contactlessly detected by a diameter measuring device 11. With a known cross-sectional form, this diameter can be used to calculate the volume per running meter and, taking into account the known relative density, the weight per meter of the bar material running into the rolling stand 3.

(13) The speed V.sub.E of the end product 2 emerging from the rolling stand 3 is likewise measured, to be precise with the aid of a speed measuring device 22.

(14) From the known or determined volume per meter or the weight per meter of the starting product and by means of the ratio of the two speeds V.sub.A/V.sub.E, the material volume per meter or the weight per meter of the end product 2 is determined. After that, the average material cross section F.sub.NE is calculated from the material volume per meter, and from that the diameter D.sub.N of the virtual, round end product is determined.

(15) Furthermore, at least one diameter D.sub.E of the end product 2 obtained is determined with the aid of a diameter measuring device 21.

(16) From the two variables D.sub.E and V.sub.E, what is known as an enveloping shell volume per meter, and in particular an enveloping cylinder volume, is calculated. Contained in this enveloping shell volume is on the one hand the material volume of the produced weight per meter of the end product 2 and also additionally the empty volume created by the stamping.

(17) For the diameter measurement of the profiled bar material according to the invention, the measuring device that is schematically represented in FIG. 5 may be used, to be precise for the diameter measurement both of the starting product and of the end product. Such measuring devices operate contactlessly and have long been known.

(18) In the case of the measuring device that is shown in FIG. 5, a measuring unit 4, 5, 6 is used for the diameter measurement of the end product. These measuring units 4, 5, 6 have in each case a laser scanner comprising a light-sensitive sensor and a laser. The bar material 2 is illuminated by the parallel laser beam from each of the laser scanners in such a way that the end product casts two shadow edges 7, 8 on the associated sensor. For reasons of better representation, in the case of FIG. 5 this is only shown for the laser scanner 5. The distance between the two shadow edges 7, 8 represents the diameter.

(19) In the case of the measuring device that is shown in FIG. 5, the laser scanners 5, 6, 7 are arranged at an angle of 120 in relation to one another and determine the diameters D.sub.E1, D.sub.E2, D.sub.E3 contactlessly.

(20) Such measuring units are described for example in DE123172A, JP56-117107A and WO2008/122385.

(21) FIG. 5 describes the situation for a three-sided rebar with a raised ribbing. The shadow edges of the three measuring units 5, 6, 7 lie in each case tangentially on one side against a rib and on the other side against a region in which there is no rib. The shaded region 9 of the end product 2 represents the cross section of the core region of the bar material without ribs, while the unshaded, crescent-shaped region lying against the end product 2 on the outside represents the region of the ribs 10.

(22) FIG. 6 shows how a circular cross section that represents the cross section of the enveloping shell can be readily calculated from only one of the three measured diameters D.sub.E1, D.sub.E2, D.sub.E3, where F.sub.NE represents the average cross-sectional area of the end product, from which the diameter D.sub.N of the virtual, round end product is calculated by the given formula.

(23) The rib height h.sub.R of the ribs 10 and also the virtual enveloping shell as enveloping cylinder 14 are shown in FIG. 7.

(24) On the basis of the embodiment given by way of example, the operating mode, actual measured values and results of the evaluation are described and logically deduced figures are given for the necessary manual or automatic control interventions in the rolling process.

(25) Starting product, round structural steel

(26) diameter D.sub.A: 22 mm

(27) initial cross section: 380 mm.sup.2

(28) diameter measuring device: 1-axis, laser shadow method

(29) weight per meter G.sub.A: 2.98 kg/m

(30) initial speed V.sub.A: 6.62 m/sec

(31) speed measuring device: optical laser Doppler method

(32) End product, concrete reinforcing steel ribbed on three sides nominal weight per meter G.sub.E: 0.395 kg/m, allowed tolerance 4% to +5%

(33) diameter D.sub.N of a virtual, round end product: 8 mm

(34) average cross section F.sub.NE of the end product: 50.3 mm.sup.2

(35) diameter D.sub.E of the virtual, round end product: 8.6 mm

(36) diameter measuring device: 6-axis laser shadow method

(37) final speed V.sub.E: 50 m/sec

(38) speed measuring device: optical laser Doppler method

(39) PKG.sub.set based on diameter: 0.6 mm, allowed tolerance: +/2% (alternatively, PKG.sub.set may also be based on the difference of the derived variables, cross-sectional areas, volumes per meter or weights per meter).

(40) The diameter-based PKG is calculated in accordance with the following formula:
PKG.sub.set=D.sub.ED.sub.N
gives for the example explained here 8.68=0.6 mm
D.sub.E as the diameter of the enveloping cylinder of the end product
D.sub.N as the average diameter of the end product, calculated from the measured initial diameter D.sub.A and the speed ratio V.sub.A/V.sub.E with the formula:
D.sub.N=square root of (D.sub.A.sup.2V.sub.A/V.sub.E)

(41) Parameters and control interventions of the shaping process

(42) initial weight per meter G.sub.A, dependent on the starting product

(43) initial diameter D.sub.A, measured

(44) initial speed V.sub.A, measured

(45) final diameter D.sub.E, measured

(46) final speed V.sub.E, measured

(47) speed ratio V.sub.A/V.sub.E as an automatic control intervention

(48) infeed of the rolling stands, in particular the last stamping rollers, as a manual or automatic control intervention

(49) A basic prerequisite for the starting of a rolling line is a perfect alignment and setting of the individual rolling stands. This process is known and is not explained any further.

(50) In a first step, the stamping rollers 31 are not closed and operation of the production line is started, until the required weight per meter is achieved at the end of the line.

(51) After reaching the setpoint value for the weight per meter, the stamping rollers 31 are infed and adjusted in dependence on the established deviation of the determined characteristic stamping variable PKG from the required PKG.sub.set, until the PKG value lies within the required tolerance limit.

(52) Following that, primarily the PKG value is fixed as the quality-determining variable and then controlled. This is possible independently of the deviations of the weight per meter within the allowed large tolerance range.

(53) The continuous checking of the characteristic stamping variable PKG according to the invention during the rolling process makes it possible to maintain the characteristic variable f.sub.R, described in more detail at the beginning, as the related rib area, since the elevation of the profile by the ribs that is expressed in the PKG, measured on the basis of the enveloping diameter D.sub.E, has a direct reference to the related rib area. By definition, the related rib area comprises the ratio between the rib flank area and the circumferential surface between two ribs that are adjacent in the longitudinal direction. Like the PKG, the f.sub.R value thus only varies insignificantly if the diameter changes within the practical tolerances. Put simply, under these conditions it is achieved that the stamping rollers are always completely filled, largely independently of the deviations of the weight per meter.

(54) In practice, it is of course attempted to make the greatest possible use of the tolerances, that is to say to operate with the weight per meter of the end product as close as possible to the 4%. With the PKG control, this is possible without risk, since maintenance of the related rib area f.sub.R is thereby ensured. Conversely, even with a possible excessive weight per meter, the f.sub.R value is automatically ensured without the risk of form defects in the product due to an overfilling of the stamping rollers, since they can be manually opened by the necessary amount on the basis of a message from the evaluation unit or directly controlled by an automatic infeed, if available.

DESIGNATION OF THE REFERENCE SIGNS

(55) Method Elements

(56) 1 starting product 11 diameter measuring device for starting product 12 speed measuring device for starting product 2 end product (profiled or ribbed concrete reinforcing steel) 21 diameter measuring device for end product 22 speed measuring device for end product 3 shaping process 31 stamping rollers 4, 5, 6 measuring units 7, 8 shadow edges 9 core region of the end product 2 10 rib 14 enveloping shell h.sub.R rib height
Parameters of the Starting Product (Localized before the Last Shaping Process) D.sub.A initial diameter, measured F.sub.A initial cross-sectional area, calculated for example on the basis of D.sub.A V.sub.A initial speed, measured G.sub.A initial weight per unit of length, for example initial weight per meter, calculated on the basis of V.sub.A and the relative density relative density
Parameters of the End Product (Localized after the Shaping Process) D.sub.E diameter of the virtual enveloping shell, measured D.sub.E1; D.sub.E2; D.sub.E3 examples of diameter values in FIG. 5 for the determination of D.sub.E F.sub.E cross-sectional area of the virtual enveloping shell, calculated on the basis for example of D.sub.E or measured with the aid of a profile measuring method V.sub.E emerging speed of the end product, measured F.sub.NE average cross-sectional area of the end product, calculated from F.sub.NE=F.sub.AV.sub.A/V.sub.E D.sub.N diameter of a virtual, round end product calculated on the basis of F.sub.NE G.sub.E weight per unit length, for example average weight per meter, calculated from G.sub.E=G.sub.AV.sub.A/V.sub.E (G.sub.A=initial weight per unit of length) or from G.sub.E=F.sub.NE PKG characteristic stamping variable from PKG=D.sub.ED.sub.N (based on the diameter values)