US2378044A - Armor plate quenching - Google Patents

Description

J c. E. SORENSEN ETAL 2,378,044

ARMOR PLATE QUENGHING Filed May 17, 1943 N Q M [Q m m mam.

.. Patented June 12, 1945 UNITED STATES; PATENT OFFICE" samoarmraqnnncnmo Charles E. Sorensen, Detroit, and Russell H. Me- Carroll and Nicholas E. Bothenthaler, Dearborn, Mich., assignors to Ford Motor Company, Dearborn, Mich, a corporation of Delaware Application May, 1943, Serial No. 487,276 2 Claims. (01. ass-e) This invention concerns metal processing and, more particularly, a method of straightening and heat-treating armor and other large plates utilizing a spray quench.

This invention concerns the heat-treatment of thick metal plates and is particularly directed to apparatus by means of which such plates may be quenched without warping. For a more complete description of the problems and difllculties encountered in this work, attention is directed to copending application Serial No. 454,576, of which this is a continuation in part.

The present invention comprises the use of Pressure platens in which the metal treated can be subjected to initial pressure and means by which a-coolant may be uniformly directed over the surface of metal so held to efiect the desired heat-treatment. In the earlier application referred to, the quench was obtained by circulating coolant in conduits within press platens proper and thus cooling the platen surfaces to a point at which the desired cooling effect on the work was obtained. This has many advantages, particularly with the lighter plate, and results in work which is warp free and properly quenched. However, when used with a heavier plate, the pressure required is excessive and the amount of heat which must be removed in a short time to obtain the desired hardening, is beyond the capacity of the coolant. Nevertheless, the basic principle of first subjecting the work to be heat-treated to sufiicient pressure to straighten it and to prevent its warping and then instantaneously quenching it while held in that position, is used in the present case as well. An advantage over the present one is thatit permits the heat-treatment of a heavier armor plate and yet effects a very sharp core quench to obtain the core hardness required for ordnance work. Other advantages reside in the lower press capacity required, the lower cost of the platens required, and the increased speed at which the operation can be carried out.

With these and other objects in view, the invention consists in thearrangement, construction and combination of various parts of the improved device, expressed in the specification, claimed in the claims, and illustrated in the accompanying drawing in which:

Figure '1 is an elevation of one form of press and platens used in the invention, a portion thereof being in section.

Figure 3 is a plan view, on an enlarged scale, of one of the platens, a portion of'the surface being removed to show the underlying fluid con nections.

Referring now to Figure -1, a typical press 9 is shown set up to practice this invention, the press mechanism itself not being shown in detail since it may be of any conventional form. Reference character Ill represents the plate to be straightened and quenched resting on the lower platen 'I] which overlies the coolant-distributing section .12, both of them being secured to the bed l3 of the press 9. The upper platen M, of identical structure and .equipped with similar facilities for coolant distribution, is secured to the head IS. A spray shield l6 surrounds and moves with the head is and the gutter ll, equipped'with the outlet pipe I8, is secured to the bed I3. I An automatic limit switch 35 having an extending actuating arm 36 and roller 31 is mounted on the upper face of the platen II in such a position that the roller may engage the work Ill. The limit switch is set so that when the work is forced into contact with the lower bosses la, the valve 38 in the supply line 39 leading to the intake pipe 21 is automatically opened through the circuit indicated at 40 supplying quenching fluid.

Each platen, H or M, is formed of cast iron and has a number of bosses l9 projecting from the surface in a substantially regular pattern (as best seen in Figure 3), these bosses having a working face 20 and communicate through a hollow center 2| with the bottom of the platen. In addition, a plurality of spray holes 22 is drilled through the material of the boss from points adjacent the-working face to the hollow center 2 I. The distributing plate, also of cast iron, has a number of intersecti'ngchannels 23 formed on its upper surface which are in communication Figure 2 is a view, on an enlarged scale, of a with transverse headers 24, which in turn communicate by the leads 25fand the supply line 26 with the intake pipe 21 which runs the length of the press. The points of intersection 28 of the channels 23 on section l2, correspond with the location of the bosses IS on the platen H sothat a plurality of channels is provided in every instance for fluid flow to each boss.

A number of rollers 29 is secured to auxiliary bosses 32 spaced at intervals on the platen II by means of spring arms 30 which are sufficiently strong to support the work above the bosses during feeding and removal, but which are depressed when the working pressure is applied to the plate. The rollers are maintained in alignment by the rigid rel-rs u The coolant is fed through the head is and bed I! of the press to the intake pipe 21. then through the supply pipes It, leads 2! and transverse headers 24 in the distributing section II to the channels 2! from which it is fed to the bosses I9 and sprayed against the surface of the plate It through spray holes 22. The sprayed coolant drains from the upper surface of the plate In and from the lower platen ii to the gutter II from which it flows to the outlet pipe it. As was the case in the prior application, the flow of the coolant through the platens is strictly regulated to obtain a sumciently high velocity to avoid the formation of steam pockets. although the danger of this occurring is considerably less in the present instance than in the former where the entire surface of the platen was in direct contact with the work.

In operation, the press is opened; the plate It is rolled into position on the rollers 18; the press head I is brought down into engagement with work depressing the rollers so that the bosses I! on the upper and lower platens bear directly against the work; suitable pressure is applied and, simultaneously, a quenching spray of coolant impinges on the plate from the numerous spray holes in the bosses. This quenches the plate to the desired core hardness and at the same time warpage or deformation is prevented by means of the pressure applied through the platens.

The principal advantage of this invention is that heavier plates may be handled and restrained from warpage by presses oisubstantialiy lower capacity than those required when a solid platen is used. At the same time a superior quenching effect is obtained because of the volume or coolant that can be brought into instantaneous contact with the heated surface and as quickly removed to permit continuous coolant circulation by the spray. The flow of coolant through the bosses ll cools their working surface sothat the area of immediate contact (if properly proportioned) between the bosses l9 and plate It is quenched at approximately the same rate as the portion of plate exposed to the spray.

In the preferred form, the total working race area of the bosses should be 10 per cent of the platen area and not less than five or more than 15 per cent of that area. The diameter of the individual boss should not be in excess of twice the thickness of the plate to be worked on. A spacing chosen in these ranges of total area and of individual boss diameters is adequate to support the plate against warpage and while the boss pressure is high, the over-all pressure and the required press capacity are low. As a comparison, a 700- ton pressure is required in spray-quenching a standard armor plate while with the internally cooled platen, at least 2,400 tons is required for the same size plate. The spray-quenching platen has been found to have a longer life, for this among other reasons, than the internally cooled platen and this is a considerable item when the size of the work treated is noted. The quench obtained with the spray is slightly faster than that obtainable with the best platen practice so aavaou.

that a somewhat higher Brinell may be obtained,

although the results from the platen are, in general, satisfactory for most requirements. Great care must be taken to have the internally cooled platen, when used, absolutely flat to give uniform pressure and to prevent water from standing on it, for if the latter occurs when the plate is brought into position, the plate areas adjacent this standing water will be initially surface quenched and the metallurgical characteristics of the plate will vary. Using spray quenching, the area of the bosses (about -10 per cent, as explained above) is so small that it is not difficult to keep them flat and dry, and even if some of them do retain a surface film of water the amount is so small that the quenching effect is practically nil. Though some scaling does occur, the spray is so rapid that the thickness of the scale is not objectionable and it is loose and readily removable. Since the water in contact with the quenching fluid is circulated around the plate with great rapidity, the quenching time is small, as compared with other quenching methods, two and a half minutes at the most being required to quench a diflicult plate from the furnace temperature of 1,650 F.

Some changes may be made in the arrangement, construction and combination of the various parts of the improved device and of the steps of the improved method without departing from the spirit of the invention and it is the intention to cover by the claims, such changes as may reasonably be included within the scope thereof.

The invention claimed is:

1. In a metal-working press adapted for straightening and quenching operations on armor and other like plate of substantial thickness, a bed, a platen secured thereto, a head, a second platen secured thereto, projecting bosses having flat working faces arranged in juxtaposition on 40 the opposed faces of said platens, said bosses being hollow and having nozzles formed therein adjacent the working faces thereof, coolant fluid connections including a valve leading to said bosses, and means for simultaneously actuating said valve and said platens to project coolant fluid from said bosses when said bosses compressively engage the workpiece.

2. In a metal-working press adapted for straightening and quenching operations on armor and other like plate of substantial thickness, a bed, a platen on said bed, a head, a second platen carriedby said head, a plurality of projecting bosses having substantially flat working faces arranged on the opposed faces of said platens, said bosses being hollow and having nozzles formed therein adjacent the working faces thereof, coolant fiuid connections including a valve to the interior of said bosses means for simultaneously actuating the valve and said platens to project coolant fluid from said bosses when said bosses compressively-engage the workpiece and resilient means on said lower platen urging such workpiece out of contact with said bosses on said lower

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