US 2893409 A
Description (OCR text may contain errors)
CARL-ADOLF WULF 2,893,409 APPARATUS AND METHOD FOR COOLING OR QUENCHING July 7, 1959 Filed June 19, 1956 APPARATUS AND METHOD FOR COOLING Ca -Ad f u f Rem c eh Ge m n i to DiitScht: Edelstahlwerke 'Aktiengesellsc'haft, -Krefeld,
' Annemarie .1 ?AQ5.
rflqr wri' utthn h 49. .5,
This invention relates to an apparatus for delivering a cooling 1:..auea hing medium ma ia-t flow to the surface of a workpiece a d f r distributing the semen aeven film over the su aceof the iwqrk .it is desired to' cooll when delivering the quenching medium, for instancein surface hardening'proces'ses,either for treating the entire surface at the same time or progressively, the prevention of soft spot fornia'tionds kno a matter of the utmost" impbr tance. Irr this' c direction a large number of proposals have already been made. The majority of these proposals substantially consist in allowing the quenching medium to be delivered through a slot extending over the entire width of the work. Attempts have also been made by employing various angular dispositions to control the delivery of the liquid in such a manner that it will form an even film over the surface, and it was recognized that the selection of an appropriate angle is a matter of especial importance. However, if the liquid was fed to the slot through one or a plurality of pipes the desired result could not be achieved because the liquid tended to form a pronounced surge in the vicinity of the end of each delivery pipe. The distribution of the liquid along the length of the slot was not therefore sufiiciently uniform. The surge causes a non-laminar flow in the film and this produces further irregularities. To deal with this problem a distributing chamber was provided into which the liquid was discharged from the feed pipes, and the liquid was then delivered to the space immediately preceding the slot through a plurality of holes. However, the provision of such a distributing chamber does not by itself provide the necessary conditions for the creation of an evenly distributed laminar film of medium over the surface of the work, nor has it been previously recognized why this should be so.
On the face of the problem it might have been expected that if the chamber were made sufliciently large and the delivery openings were sufiiciently evenly spaced the desired uniform distribution of the medium would be bound to result. However, experience has shown that this is not so, and that other factors also influence the result. Proposals have been made to use distributing chambers of comparatively large size and to have an even distribution of the delivery openings, but it has not been realised that it is essential for the liquid inside the distributing chamber to be subjected essentially to static pressure and to rely on dynamic pressures between the chamber and the opening through which the medium is finally discharged without the creation of considerable static pressure in the liquid flowing from the chamber to the slot from which it emerges.
The present invention is based on the recognition of this condition, and the invention therefore proposes to construct the quenching apparatus in such a way that the cross-sections of the flow channel between a preliminary chamber in which a practically exclusively static pressure is built up actually increase between the discharge opening from the chamber (inlet to the channel) and the de Un ed sees P m twee h r m nar h v n t e s P 2,893,409 en d uly 19? livery opening from which the liquid emerges from channel onto the surface of the work. Ifthis is the case the desired laminar'film that will cling to the surface of rk n n e t e de r d qu n h n fl can be obtained. It is possible by increasing the volume of liquid delivered to the preliminary chamberftoregulate the quantity of quenching medium within the'required limits. I
It is possible steadily to increase the cross section be- However, it is a considerable advantage if. the flow sectionsare int m te f oh n s s s a m so u i n a ts to i c as the flo s ti n bf 11 9 i e Parti o .Wfl' t n o e or er i termedi t hambers; j e ee- .tures of the invention are japplicableto any quenching ce i h a del ve a u sr v ya to w en: the device is intended for quenching flat surfaeesfsuch as sheets and the like, or cylindrical bodies, in which case the slot must be of annular shape.
With reference to the accompanying drawing a ringlike f m of ons u tion c u n ani nnu ar lot an S a le for q en h ns i dri a WQrIkI w li e er after more particularly described as an illustrative x; ample of the invention. The'drawing shows a vertical section through the ring-shaped body of the apparatus.
Arranged inside the hollow ring is a preliminary chamber 1 which receives the liquid from a pipe 2 of large cross-section. The preliminary chamber is created within the hollow body by the provision of a partition wall 3.
Following chamber 1 is a further chamber 4 created by the above mentioned partition wall 3 and a further partition wall 5. The slot through which the medium emerges in the form of a funnel-shaped film on to the surface of the work, not shown, is indicated at 6.
The liquid flows from chamber 1 through the opening 7 into chamber 4 from where it passes through openings 8 into the chamber 9 which directly precedes the slot 6. According to the invention the flow sections are such that the total flow section through the openings 7 is the smallest section of the channel from chamber 1 to slot 6. The flow section offered by the openings 8 is greater than that of 7, but it is smaller than the flow section through the discharge opening at 6.
These comparative sections refer to the total cross section available for the passage of the liquid. It must be determined in each individual case whether it may be better to provide a small number of large section holes or a large number of correspondingly smaller section holes of circular or some other shape for the passage of the medium at 7 and 8. In view of the large cross-section 2 of the delivery pipe into the preliminary chamber and the small exit openings at 7 a substantially static pressure will be created inside this chamber. However, since the flow sections increase from the openings 7 to the slot 6 relatively to the flow section of opening 7, dynamic pressure rather than static pressure is produced in this part of the path of the medium which will issue evenly and without turbulence from the slot to form the desired film. The effect is the same if the slot is linear instead of an annulus, as would be required for treating flat work.
It will be readily understood that in certain circumstances the one chamber 4 may be replaced by several such chambers. However, as a general rule, one chamber should be suflicient.
The features of the present invention are directly opposed to the characteristic features of known devices which insist, at least in the region of the slot opening, on a reduction in the section of flow. Generally speaking, the flow paths provided in known apparatus tend to decrease between the actual supply and the final opening through which the medium is discharged on to the sur face of the work. The apparatus according to the invention which is somewhat schematically examplified by the drawing, is particularly suited to the quenching of rolls, especially cold rolls, which have been inductively heated to the temperature incidental to hardening by the continuous progression method. The quenching device would be associated with the inductor and follow the same. However, there is no reason why an apparatus according to the invention should not be adapted to the quenching of such, and other types of work, when heating to the requisite temperature is achieved by means of burners.
What I claim is:
1. Apparatus for distributing a cooling medium over the surface of a workpiece to be cooled, comprising at least one annular preliminary chamber wherein the medium is adapted to be subjected to only substantially static pressure and an annular discharge channel com- .prising an inlet from said preliminary chamber constituted by at least one opening and a delivery opening for discharge of the cooling medium, said channel comprising at least three constrictions, the first of which forms the said inlet and the last of which forms the said delivery opening, each said constriction in the direction of the discharge flow being greater in flow section than the preceding constriction, and each pair of constrictions being separated by an enlargement of the channel.
2. Apparatus according to claim 1, comprising a chamber having a wall in which the delivery opening is situated, said chamber being divided by partitions into at least three compartments, each said partition having at least one flow-controlling opening, one compartment forming the said annular preliminary chamber and the other compartments comprising part of the said annular discharge channel, the opening in the partition which forms one wall of the preliminary chamber forming the said inlet and the compartment remoted from the said preliminary chamber having the said delivery opening and the openings in each partition permitting communication between the compartments on either side of it and the controlling flow area of the partition openings being greater from partition to partition in the direction of discharge but less than that of the delivery opening.
References Cited in the file of this patent UNITED STATES PATENTS 2,329,188 Dennen et a1. Sept. 14, 1943 2,376,515 Somes May 22, 1945 2,542,237 Dewey Feb. 20, 1951 2,657,698 Garrett Nov. 3, 1953 FOREIGN PATENTS 660,144 Great Britain Oct. 31, 1951