ES2222839B1 - PROCEDURE FOR THE MANUFACTURE OF CALIBRATED STEEL BARS FREE OF DEFECTS AND INSTALLATION FOR MANUFACTURING. - Google Patents

Abstract

The drawing/calibrating step is combined with a crack control step (7) and a subsequent mechanical stripping step (8) for removing shavings before cutting. The calibrated crack detection depth corresponds to the surface defects on the bar and is slightly less than the stripping depth. A process for producing laminated steel bars comprises the following steps: (A) supplying a hot-laminated wire rod material from a reel (1) to a pre-straightening step (2) and a bump removal step (3); (B) carrying out a combined drawing and calibrating step; (C) checking for cracks; (D) cutting; (E) straightening; and (F) classifying the bars as being either suitable for commercial use (12) or defective (12'). The drawing/calibrating step is combined with the crack control step and a subsequent mechanical stripping step (8) in which shavings are removed is carried out prior to the cutting step. The calibrated crack detection depth corresponds to the surface defects on the bar and is slightly less than the stripping depth. Information concerning the percentage of bars rejected due to cracks is fed back to the drawing/calibrating and stripping steps in order to readjust the laminating and stripping diameters.

Description

Procedure for the manufacture of bars calibrated steel free of defects and installation for your manufacturing.

The present invention is intended to give know a procedure for the manufacture of steel bars calibrated free of defects, as well as industrial installation which allows to carry out the aforementioned procedure.

Currently, procedures are known for the manufacture of calibrated steel bars that allow to achieve calibrated bars for the manufacture of mechanical parts that meet certain characteristics of dimensions of diameter and external tolerances and which are subjected during crack-proof manufacturing to avoid as much as possible defective bars.

The increased demands on the bars calibrated, forcing rigorously the elimination of defects, especially superficial cracks, has represented the need, in this industrial sector, to achieve procedures and facilities for manufacturing defect-free bars, combined with satisfactory characteristics of industrialization of the procedure.

At present, to transform steel hot rolled, which is the raw material used for the manufacture of calibrated steel bars, they are mainly known two procedures, namely: cold drawing and turning or barking of the bars.

In the first case, we proceed to pass the hot rolled steel in rolls, that is, the so-called wire rod, previously cleaned of the hot rolled own calamine, to through a row that has a reduction cone and a part cylindrical calibration, leaving the wire with greater roundness and a certain tolerance in diameter of the order of 0.1 mm and a surface smoother

To carry out the currently known method cold drawn, facilities that are called are used combined stretching machines, which usually comprise the following parts:

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A winder

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A previous straightener.

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A calamine cleaning machine, by blasting jets or brushes

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A group of stretched by cars, where the row is located and produces the reduction of the section.

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Two groups of straightening rollers, horizontal and vertical, between which is used to locate the detection equipment of cracks

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A synchronized cutting system.

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A roller or nozzle straightening system, which includes a system of feeding, unloading and classification.

The crack detection systems by Induced currents that are used in these combined machines, allow to detect defects with minimum depths approximately 0.15 mm, so the bars transformed by this procedure may have defects of such depth.

The process of turning the bars consists of Pass the wire rod through multi-blade heads static or rotary that by chip removal reduce the diameter of the wire rod leaving it with greater roundness, lower tolerance and removing most of the defects with the chip Typical surfaces of hot rolled wire rod.

For the realization of manufacturing methods by turning, there are facilities that usually include the following elements:

- Winder

- Previous straightener

- Previous laminator (optional) or straightener rotary

- Cutting system

- Straightened system (optional)

On the bar turning lines, given the roughness of the wire rod and / or its lack of roundness, once Laminate operation performed, do not carry detection equipment prior to turning, being able to use these at the end of the process with a maximum detection depth of approximately 0.15 mm, if it includes a polished straightening system.

To get the manufacture of bars calibrated without defects in a properly industrialized way, the The present invention provides a method in which it is proceeded from the hot rolled wire rod coil to an operation of pre-straightened and later decaminated, proceeding then to the combination of a stretch calibration phase and a intermediate crack control process to detect the depth of bar defects according to a tared depth, whose defects are then eliminated in an operation of peeled, with a chip removal depth greater than detection equipment setting. Therefore, the setting is carried out of the detection equipment at a depth corresponding to the experimentally detected defects in the bars, and will proceed to the stripping of the bars with the elimination of a part of material which will correspond to the detection depth plus a surplus determined, so that greater security will be achieved in the total cleaning of the bar, detecting said detection zone eventually areas where defects are greater than the setting of the detection equipment, resulting in bars that will be separated automatically at the end of the process according to the methods universally known reference of the defects of the continuous type bars, to locate at the end the bars that They present defects and allow their elimination. However, all defects within the setting value of the device detection, will be automatically eliminated by the phase of turning the bars that will eliminate a quantity of material corresponding to the setting plus a small safety margin.

The procedure will therefore allow guarantee the absence of surface defects detectable by current control equipment.

The process object of the present invention it will involve the possibility of feedback of results to the phase cold calibration of the installation, since in the case of that the number of bars discarded in the final stage as a result of the intermediate classification is very high, the peeling depth, simultaneously changing the row of calibrated to a larger diameter, to allow the material have enough surplus for the elimination of cracks and allow to achieve the nominal diameter of the calibrated bar. Obviously, in the case where there are no rejections in absolute, this will mean that the calibration of the device is due make at a lower value, avoiding excessive losses of material by chip removal.

Therefore, by applying this corresponding process and installation, the absence of surface defects and minimize chip losses or material rejected by the depth of defects detected.

For your better understanding they are attached, by title Explanatory example but not limiting, some drawings representative of the present invention.

Figure 1 shows an outline of the set of Elements interested in the present invention.

Figure 2 schematically shows the interrelationship of bar diameters from the starting wire rod up to the final calibrated bar with the surpluses corresponding.

As seen in Figure 1, the procedure starts on the coil (1) of rolled wire rod in hot from which the wire rod is removed to a phase of pre-straightened (2), and then to phase (3) of elimination of superficial residues or calamine, by blasting or brushing systems, which achieves the wire rod (4) straightened and decaminated which then passes to a stretch calibration phase comprising a row and a group of traction, which have been represented with the numeral (5). TO then the calibrated wire rod (6) will pass to the control system (7) that will be set for the detection of cracks at a given depth, referencing the places of the continuous bar in the that are located areas with defects greater than the setting of the machine. Then, the calibrated wire rod goes to the system mechanization (8) in which it will proceed mechanically to eliminate a shallow part of the bar somewhat larger than the setting of the control system, thereby eliminating defects superficial systematically. The wire rod will pass next to the cutting phase (9), after which it will be sent to the whole straightening (10) finally passing through the selection zone of bars (11) where the bars that meet the expected conditions (12) will be considered as marketable bars and bars defective (12 ') in which depth has previously been detected of defect superior to the setting of the machine will be eliminated.

In figure 2 it has been represented schematically the procedure in which the diameter is observed (\ Phib) of the wire rod after cold drawing, in which there are multiple defects due to surface cracks, such as (d1), (d2), (d3) ..., which remain within the setting value (A) of the machine. It is possible that some defect such as (d4) is greater than setting value, giving rise to a reference annotation in the detection zone that will cause automatic rejection of the bar when end of the line The setting of the crack detection machine it will be done with the value (A) indicated in the graph, and the turning will be done by eliminating the surplus (B) that comprises the tare (A) plus a small safety surplus (\ varepsilon) that It has been indicated in the graph, giving rise to the diameter nominal (\ phi_ {n}) of the bar you wish to obtain.

Information feedback may be perform, in case the number of bars removed by cracks be excessive, rolling the bar to a diameter (\ phi_ {b}) something greater so that it allows to increase the turning surplus (B), eliminating defects and producing bars at the end of the process clean of defects. Otherwise, that is, where you can decrease the raw diameter (\ phi_ {b}), it would proceed so inverse in the lamination phase, reducing the excess of material with respect to the nominal diameter (phB).

Together, by applying the installation procedure object of the invention will be achieved completely ensure the absence of superficial defects of form duly industrialized, getting the minimum loss for shavings or materials rejected on the line.

Everything that does not affect, alter, change or modify the essence of the procedure described will be variable for the purpose of the present invention.

Claims (4)

1. Process for the manufacture of rolled steel bars of the type comprising the feeding of a rolling line from hot rolled wire rod coil with a pre-straightened and de-laminated phase, then passed to stretch calibration, crack control and cutting and straightening, with a final classification of acceptable and unacceptable bars, characterized by combining the stretch calibration operation with a crack control phase and a subsequent mechanical barking operation of the bar by chip removal, prior to the cutting of the bars, so that the depth of tare of the detection of cracks has a value corresponding to the surface defects of the bar and somewhat less than the depth of debarking of the successive phase of peeling of the bar, whereby the Automatic elimination of defective bars. 2. Process for manufacturing rolled steel bars, according to claim 1, characterized in that the feedback is carried out towards the stretch calibration phase and the debarking phase of information on percentages of bars eliminated by cracks in the final classification of bars so that, if it exceeds a certain control value, the outer diameter of the wire rod roughing will be increased, as well as the debarking depth to allow the elimination of defective bars. 3. Process for the manufacture of rolled steel bars, according to claim 1, characterized in that information is produced from the final phase of classifying bars to the phase of lamination of wire rod roughing, reducing the diameter of the raw wire rod and the depth of debarking in the stripping phase of the bar in case the reduction of defects in the bars in final classification allows reducing the excess of material removed by debarking. 4. Installation for the manufacture of calibrated steel bars capable of carrying out the procedure of claims 1 to 3, presenting a pre-straightening unit after the hot rolled wire feed coil and subsequently a de-laminating unit, characterized by comprising the combination of a stretch calibration unit with a crack control system and a bar debarking system successive and prior to the cutting of the bars, allowing continuous and depth-adjustable peeling of the bars calibrated by stretched, which allows the systematic removal of the continuous bar layer that presents superficial defects.