US3508979A

US3508979A - Method for cooling workpieces

Info

Publication number: US3508979A
Application number: US532919A
Authority: US
Inventors: Otto Modder
Original assignee: Siegener Maschinenbau GmbH
Current assignee: Siegener Maschinenbau GmbH
Priority date: 1965-03-20
Filing date: 1966-03-09
Publication date: 1970-04-28
Anticipated expiration: 1987-04-28
Also published as: GB1139463A; FR1471791A; BE678031A

Description

April 28, 1970 o. MODDER 3,508,979

METHOD FOR COOLING WORKPIECES Filed March 9, 1966 HHV@ -. :ffffMl-|; 1H

IN\{ ENTOR OTTO MODDER HIS ATTORNEY United States Patent C US. Cl. 148-12.4 2 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for the rapid cooling of rolled materials from rolling temperature to room temperature and, more particularly, to materials such as sheets, billets or the like that are sensitive to stresses and distortion.

It is known in the art that hot rolled material, when leaving the last rolling mill stand, can be cooled on hot beds to a desired final temperature, e.g. room temperature. After the individual lengths of rolled stock arrive on the hot bed they are moved forward essentially perpendicular to their longitudinal axes at a low conveying speed such that successive lengths of rolled stock come to rest on the hot bed next to one another with practically zero clearance between them.

The cooling from rolling temperature which may be as high as 1100 C. down to about 650 C. occurs relatively rapidly because the temperature difference is relatively great between rolling temperature and room temperature. On the other hand, the cooling of the rolled material from 650 C. down to room temperature requires a considerably longer period of time as the removal of heat proceeds substantially slower, due to the smaller temperature dilference between the cooling stock and the surrounding medium provoking the heat evacuation, which in this case, it is the ambient air. Under these conditions the hot beds, especially with the present-day rolling speed, must be very large and designed under considerable expenditure and substantial space requirement.

For the rapid cooling of heavy rolled material, e.g. blooms or slabs, it is also known in the art to dip the material into water or a similar liquid coolant and move it therein to a certain extent in order to avoid the formation of steam bubbles. The liquid coolant brings about essentially better heat evacuation and, therefore, accelerated cooling of the rolled material, especially when the coolant is subject to continuous agitation. Direct cooling of rolled material with relatively small sections, such as billets, sheets, bars, sections or the like, in water or a similar coolant was heretofore unfeasible, because such rolled material became warped and twisted as the result of frequently occurring thermal stresses. Further processing of this material, therefore, would be impossible in many cases. To this day, therefore, small-section rolled material has been cooled from the rolling temperature down to the desired end temperature while making use of the conventional hot beds that are large in their layout and, therefore, procurable only at considerable expenditures.

It is the object of the present invention to eliminate the aforementioned drawbacks of the known art. Therefore, the invention is based on a method and apparatus for the rapid cooling of hot rolled stock, such as sheets, billets or the like, from the rolling temperature within the range of approximately 780 to 1100 C. down to room temperature and by employing said method and/or apparatus the time consumed and the constructional expenditure can be reduced to a fraction of what it used to be, without difiiculties relative to warping, bending or twisting of the rolled material. From the point of view of processing engineering the solution of this problem resides essentially in the fact that the cooling from the rolling temperature down to a temperature of about 650 C. occurs under free-air admission, whereupon the rolled product for further reduction in temperature is dipped into Water or a similar coolant.

It turned out that the danger of distortion, bending or twisting of the rolled material at a temperature below 650 C. is relatively slight, if, even though, through its immersion in a liquid coolant, e.g. water, a certain quenching sets in.

From the point of view of processing engineering it is further advantageous according to the invention if the rolled material during the entire cooling process is kept steadily under continuous or discontinuous motion.

A cooling apparatus to carry out the method according to the present invention is characterized by a hot bed of known design, eg a skid, roller, rake and lifting-beam hot bed or the like, and immediately adjacent thereto an immersion-cooling device, e.g. a cooling wheel or a cooling-swinging device.

With such a cooling system it is possible according to this invention to design the hot bed with a considerably reduced length, e.g. to one-third of the customary length, thereby cutting down substantially the expenditure for the entire cooling apparatus because the immersion-cooling. device requires relatively little installation space and it is otherwise less costly than a conventional hot bed.

In order to assure at any time trouble-free transfer of the rolled stock from the hot bed to the immersioncooliug device, it is advisable, depending on the design of the hot bed, to provide between the hot bed and the immersion-cooling device special transfer devices. Especially with cooling systems for bar stock, such as billets or sections, it is advisable to develop the transfer device in such a manner that a groupwise transfer of the rolled material to the immersion-cooling device is made possible.

These features and advantages of the present invention will be better understood when the following specification is read along with the accompanying drawing which schematically illustrates an elevational view of one embodiment thereof.

The lengths of hot rolled material 1 are delivered from a rolling mill, not shown, on an approach roller table 2 by which they are transferred to the entry end of a hot bed 3 and there lifted individually off the approach roller table 2 and delivered to the hot bed 3. The hot bed 3 may be of any desired construction, i.e. skid, roller, lifting-bea.m, or swinging-rake hot beds or the like may be employed. Represented in the drawing is a lifting-beam hot bed 3. In this case the transfer of the rolled stock lengths 1 from the approach roller table 2 to the hot bed 3 as well as the stepwise further transportation of the rolled stock lengths on the hot bed 3 occurs by means of lifting beams 4. The lifting beams 4 are alternatively raised and lowered by lifting drives 5 and a swing drive 6 is employed to move the beams during the raising in the direction of the arrow a and during lowering in the direction of the arrow b. As a result thereof, the rolled stock lengths 1 lying closely next to each other on the hot bed travel slowly toward the delivery end of the hot bed 3. The length of the hot bed 3 is then so dimensioned that the rolled stock lengths 1, while traveling over the hot bed 3, are exclusively cooled under free-air admission from the rolling temperature down to a temperature of about 650 C.

Adjacent to the delivery end of the hot bed 3 is an immersion-cooling apparatus 7 developed as a cooling wheel 9 dipping into a tank filled with liquid 8. The

lengths of rolled material 1 are transmitted purposely in groups from the hot bed 3 to the cooling wheel 9, by a delivery device of known design which shoves a given number of rolled stock lengths 1 into spokelike openings 11 formed in the cooling wheel 9. After each spoke opening 11 is loaded, the cooling wheel 9 is turned by a sector an amount corresponding to the division of the spoke openings 11, so that a next opening 11 comes to lie in an extension of the hot bed 3, whereas the preceding spoke opening with the rolled stock lengths 1 contained therein dips into the tank filled with liquid 8. In this liquid tank the rolled stock lengths 1 are cooled rapidly from the temperature amounting to about 650 C. down to the desired end temperature or room temperature. The cooled lengths of rolled material 1, on the periphery of the cooling wheel 9 at a point somewhat diametrically opposite to the hot bed 3, are moved also in a group by an ejecting device 12 coupled to the delivery device 10 out of the spoke clearance 11 and, for example, shoved directly onto a runout roller table 13.

Because the lengths of rolled material 1 cool in a relatively short time from the rolling temperature toa temperature of about 650 C., the hot bed may have a limited length. Since the rolled stock having a temperature of 650 C. can be exposed without the danger of distorting, twisting and bending to quench cooling by dipping into a liquid coolant, there results according to the invention a low-cost and space-saving cooling apparatus for rolled stock with small sections, such as billets, bars, sections and sheets.

It goes without saying that the immersion-cooling device 7, in lieu of a cooling wheel 9, can also be developed as a swing-cooling apparatus, which through a swinging motion dips the rolled material into a tank filled with liquid and removes it therefrom after cooling.

By employing the present invention, the hot bed can be reduced to a fraction of the longitudinal dimension of the past and because in addition thereto the expenditure for the immersion-cooling apparatus is substantiall lower than for a conventional hot bed, there results aside from the substantial shortening of the cooling apparatus, also a considerable reduction in the construction costs.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof. However, I desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. A method of rapidly cooling hot rolled material such as sheets, billets, bars and sections immediately following the rolling thereof, which material is sensitive to distortion and twisting caused by the development of stresses incident to cooling thereof from the rolling temperature down to room temperature comprising the steps of:

cooling said material immediately following the rolling thereof by free-air admission from its rolling temperature down to a temperature of about 650 C. and immediately thereafter,

further cooling said material by dipping it into water or similar coolant to further reduce the temperature of said material.

2. A method of rapidly cooling rolled material according to claim 1, including the additional step of imparting motion to said material during the cooling of said material by said free-air admission and during said further cooling of said material by dipping it into water or similar coolant.

References Cited UNITED STATES PATENTS RICHARD O. DEAN, Primary Examiner US. Cl. X.R. 148-143