APPARATUS AND METHOD FOR QUENCHING RODS AND TUBES

Abstract

The present invention relates to a apparatus for statically quenching a product (1) coming from a rolling plant, comprising a seat for housing the product (1) so that, when the product (1) is housed there, its main development axis (A) coincides with the positioning axis (Z), a series of nozzles (4) arranged around the positioning axis (Z), along a curvilinear surface (3), open at the bottom, and adjustable so as to dispense a flow which is tangential to the surface of the product (1). The invention also relates to a process for static quenching of the product, implementable by such apparatus.

Claims

1-5. (canceled)

6. Apparatus for statically quenching rods and tubes equipped with a main development axis (A) and coming from a rolling plant, the apparatus comprising a seat for housing a rod or tube equipped with positioning axis (Z), so that when the rod or tube is housed in the seat the main development axis (A) of the rod or tube coincides with the positioning axis (Z), a series of first external nozzles for dispensing quenching agent arranged around the positioning axis (Z), wherein the first external nozzles are arranged along a curvilinear surface, substantially equidistant from the positioning axis (Z), the first external nozzles being adjustable so as deliver a flow of quenching agent tangential to the surface of the rod or tube, wherein longitudinally moving means and lifting means are comprised for positioning the rod or tube coming from the rolling plant so that the main development axis (A) of the rod or tube coincides with the positioning axis (Z), wherein the curvilinear surface has an absence of first external nozzles which defines an opening at the bottom so that the first external nozzles are arranged asymmetrically, that possible detached pieces due to possible cracks fall freely and that the lifting means, supporting the product and permitting the evacuation, pass through the opening at the bottom of the curvilinear surface.

7. Apparatus for the static quenching according to the claim 6, characterized in that the first external nozzles are arranged on a curvilinear surface stretches for at least 180°, but less than 360°.

8. Apparatus for static quenching according to claim 6, characterized such that the first external nozzles are angularly spaced about the positioning axis (Z) with a degree less than 15°.

9. Apparatus for the static quenching according to claim 6, characterized in comprising a second internal nozzle for dispensing quenching agent arranged in correspondence of the positioning axis (Z), for quenching the inner surface of the rod or tube.

10. Apparatus for the static quenching according to claim 6, characterized in comprising rotating means in order to operate the rotation of a rod or tube about the main development axis (A), when the rod or tube is housed in the seat.

11. Process for static quenching rods and tubes equipped with a main development axis (A) and coming from a rolling plant, implementable by an apparatus according to claim 6 and comprising the following steps: receiving the rod or tube from the rolling plant positioning the rod or tube within the apparatus by longitudinally moving means positioning the rod or tube within the apparatus by lifting means passing through the bottom of the curvilinear surface so that the main development axis (A) of the rod or tube coincides with the positioning axis (Z) of the apparatus operating rotating means in order to operate the rotation of the rod or tube about the main development axis (A) opening feeding valves of the nozzles for dispensing the quenching agent and launching the quenching along a curve which is tangent to the product and is open at the bottom quenching closing feeding valves stopping rotating means moving the rod or tube by longitudinally moving means and lifting means in correspondence of a transporting device.

Description

[0037] Further aims and advantages of the present invention will become clear from the following description, which refers to an example of embodiment illustrative and preferred, but not limiting, of the apparatus for quenching rods and tubes, and the relative method, according to the present invention, and from the accompanying drawings, wherein:

[0038] FIG. 1 shows the apparatus of the invention with the rolled product to be treated on the way;

[0039] FIG. 2 shows the apparatus of FIG. 1 with the rolled product in position during the treatment.

[0040] The apparatus of the invention has the peculiarity of joining the advantages of the known technologies up to now avoiding the drawbacks.

[0041] The apparatus of the invention, in fact, provides a static quenching, so that the product 1 (a tube or a bar) to be quenched is put under the quenching agent 2, for instance water, along its entire length at the same time. Externally, the bar is quenched by a rim 3 of nozzles 4 covering a part of the circumference of the product. The nozzles 4 are adjustable so that the quenching agent 2 hits the product 1 tangentially. The product 1 is housed on rotating devices (rollers or lunettes) 5 and during the step of quenching (FIG. 2) the product 1 rotates about itself along the direction of the narrow R, about its own main development axis, perpendicular to the plane of the figure and passing by the point A. At the head of the apparatus of the invention there is a nozzle, not shown, adequately sized and shaped, which ensures an optimal flow of quenching agent even on the inner surface 6 of the product 1. At the back of the apparatus of the invention there is a hopper 7, collecting the quenching agent 2 coming from the internal nozzle after having crossed the length of the product.

[0042] As it is shown in the attached tables, the process of quenching of the invention may comprise the following steps: [0043] output of the product 1 from the furnace of quenching at an enough high speed so that the same product 1 does not cool down [0044] positioning the product 1 within the apparatus of the invention by moving rollers 8 [0045] lifting up the product 1 until the main development axis A of the product 1 coincides with the main development axis Z of the apparatus of the invention [0046] operating rotating devices 5 in order to operate the rotation of the product 1 about the axis A [0047] opening feeding valves of the nozzles 4 for dispensing the quenching agent 2 and launching the quenching [0048] quenching [0049] closing feeding valves. [0050] stopping rotating devices 5 and consequently of the rotation of the product 1 [0051] pulling down the product in correspondence of a transporting device (not shown), for instance on rollers [0052] evacuating the apparatus for quenching of the invention.

[0053] Advantageously, the tangential quenching ensures an optimal exchange on the external surface of the product 1, since the quenching agent 2 hits the product 1 with such a speed that breaks the vapour barrier.

[0054] Such efficiency is not vitiated by the absence of nozzles 4 at the bottom. In fact, unlike the existing technologies, wherein the piece is hit on the whole circumference, the piece is rotated about itself at such a speed that compensates the asymmetry of the nozzles. The cooling speed is thus connected to the single conductivity of the steel, the external surface being kept at a temperature which almost coincides with the water temperature. Unlike the traditional systems for progressive quench, the apparatus of the invention provides a quenching agent flow which is tangential to the product 1, i.e. which has not a line symmetry with respect to the axis A of the product 1. The tangential flow, in fact, increases in proportion to the contribution given by each rim 3 of nozzles 4. This permits making the quenching more or less drastic basing on the direction and on the speed of rotation of the product 1. Practically, basing on the direction of rotation R, that as shown in FIG. 2 may be clockwise or counter-clockwise, the difference in the heat exchange is comparable to the difference that there is between a heat exchange in downstream and an exchange occurring in upstream. Unlike the existing technologies, thus making the quenching more or less drastic is possible; for the steels susceptible to the cracks this possibility is very important.

[0055] Advantageously, since the bottom part of the machine is open, in case a crack occurs, possible pieces detaching from the product 1 in the machine would not damage nor hit any piece of the machine.

[0056] During the quenching the product 1 does not move axially; for cooling the inner surface of the product to be treated, thus, using a not moving nozzle, that does not completely enter within the product 1, is possible as in the case of the lances which are used at the moment for progressive quench. The non moving nozzle is suitable for optimise the inner cooling of the tube, since the section which is available for the cooling water flow coincides with the inner section of the tube, and is not partially obstructed by the lances.