US2882032A

US2882032A - Heat treatment rack

Info

Publication number: US2882032A
Application number: US481588A
Authority: US
Inventors: Fred W Garner
Original assignee: Lockheed Aircraft Corp
Current assignee: Lockheed Corp
Priority date: 1955-01-13
Filing date: 1955-01-13
Publication date: 1959-04-14
Anticipated expiration: 1976-04-14

Description

April 14, 1959 F. w. GARNER 2,882,032

' HEAT TREATMENT RACK Filed Jan. 13, 1955 IN V EN TOR.

W FRED w. GARNEIR 2 Agem nitedStates P t 01c HEAT TREATMENT RACK Fred W. Garner, .Los Angeles, Calif., assignor to Lockheed Aircraft Corporation, Burbank, Calif. Application January 13, 1955, Serial No. 481,588

2 Claims. (Cl. 263-47) This invention relates to an improved heat treatment rack to support articles being heated and then quenched to develop their full strength after forming to shape.

Heretofore, such heat treatment racks have been built up as stiff welded structures which are rigid and inflexible and therefore soon warp and sag out of shape due to the repeated heating and quenching thereof in normal use. Such racks are used to carry parts through sequential heating and quenching cycles by pushing the racks onto an elevator to be lifted into a heating oven, and after the heating cycle, lowered directly into a quenching tank. It is therefor an object of this invention to provide a heat treatment rack that will survive repeated expansion and contraction due to the heating and quenching cycles without warping, and to that end I provide bolted braces and slip joints for pliability in a vertical plane while maintaining rigidity in plan form by the use of cross-bracing.

It is a further object of this invention to provide a multiple wheeled heat treatment rack of the type described wherein the rack is alternately braced to stand upright and straight in line with bolted slip joints for vertical pliability, whereby each of the wheels carry their share of the load on an uneven floor. The vertical pliability of the rack allows the wheels to set solidly on the ground or the oven hoist with the Weight distributed over the multiple wheels thus eliminating any tendency of the rack to warp or sag into contact with the oven walls during the heating cycle.

It is another object of this invention to provide a light weight, easily handled rack of the type described to facilitate loading and unloading and reduce the heating and quenching times of the heat treatment cycle.

Other objects and advantages of my invention will appear from the following description taken in connection with the accompanying drawings, wherein:

Figure 1 is a perspective view of a heat treatment rack embodying the novel features of my invention;

Figure 2 is an enlarged detail section of one of the wheel mounts, taken on the line 22 of Figure 1;

Figure 3 is an enlarged detail section at right angles to the showing of Figure 2, taken on the line 33 of Figure 1.

As shown on the drawings:

The heat treatment rack of this invention comprises a loosely jointed rectangular framework connecting a series of axles each carrying two wheels 11. The framework comprises spacer tubes 12 between the ends of each axle, which tubes have loose or free telescopic connections with tubes 13. In the drawings I have shown the end parts of the tubes 13 engaged or telescoped in the end portions of the spacer tubes 12 with clearance, that is the inside diameters of the tubes 12 are greater than the outside diameters of their related tubes 13. The ends of the spacer tubes 12 are retained in the tubes 13 for limited axial and universal movement by bolts 27 loosely fitting their respective openings. While these loose joints perrnit relative movement between the tubes 12 and 13 2,882,032 Patented Apr. 14,

the tubes are positively connected against separation and relative motions of the related tubes are limited, flattened ends 14 bolted together at 15 and to slip tubes- 16 protruding from the ends of the .axles, as best shown in Figures 2 and .3. These connections, 15 comprise bolts 17 freely passing through oversize vertical openings in the superimposed flattened ends 14,.and tubes .=l6 and; the

tubes 16 have play or loose engagement in their respective axles 10, all as shown in Figures 2 and 3. These arrangements provide slack or give at the bolted connections, and the rectangular frame so formed is laterally or transversely stilf but vertically pliant to allow any wheel or axle to rise or fall to conform to an uneven ground. The rectangularity of the frame is further maintained by crossbracing 30 and a stiif wire screen 18 laid over the axles and fastened to the side tubes to assist in resisting lateral distortion of the rack 12. The screen 18 also serves to prevent articles being treated from dropping through the framework to the ground. u

An upper framework is formed similar to that just described with cross members 19 and longitudinal spacers 20 having slip tubes 21 bolted in the ends thereof. These frame members are loosely connected in the same manner as the tubes 12, 13 and 16 of the lower framework. Uprights 22 at each wheel location similarly have slip tubes 23 at each end, the upper and lower frameworks being tied thereto by clips 24 engaged under the head of the bolts 17 with their other ends bolted to the slip tubes 23. In alternate panels diagonal braces 25 engage between bolts 26 through the uprights 22 and the slip tubes 23 and the spacer tube 12 connecting bolt 27 to its slip tubes 13.

The upper framework is provided with cross-bracing 30 and screen stiffening 28 similar to the screen 18, which screen serves as a support for hooks (not shown) used to suspend the articles to be heat treated. By so suspending the articles, warpage thereof is greatly reduced during processing and the articles are uniformly heated and quenched during the operation. The uprights 22 carry spacers 29 with books to support an intermediate shelf if desired.

The heat treatment rack above described provides a vertically articulated multiple wheel rack wherein individual wheels may settle or be lifted by ground irregularities while carrying their share of the load. This articulation is limited to up and down movement of the wheels by the cross-bracing and screens stiffening both the upper and lower frameworks against lateral deflections. While the relative movement at any one metal to metal joint is small it is yet enough to prevent the transmission of expansion and compression strains through the joints and thus prevents warping or sagging of the rack under load and thermal stresses during the repeated heat treating cycles of heating and rapid quenching.

Having thus described my invention and the present preferred embodiments thereof, I desire to emphasize the fact that many modifications may be resorted to in manner limited only by a just interpretation of the following claims.

I claim as my invention:

1. A heat treatment rack for carrying articles to be heated and quenched comprising a plurality of axles carrying wheels for supporting the rack, each axle comprising a wheel spacing tube and a slip tube bolted to the spacer tube, top and bottom frameworks comprising spacer tubes between the axles, slip tubes loosely telescopically engaged with the ends of the spacer tubes for limited relative movement, loose-bolt connections connecting the axle slip tubes to the adjacent slip tubes of the framework spacer tubes for limited relative move- 'ment, vertical spacer tubes having slip tubes tied to the ,loose-bolt connections connecting the axle and framework slip tubes, and diagonal braces connecting the framework spacer tubes and vertical spacer tubes in alternatepmels, whereby to form a laterally stiff but vertically flexible rackincapable'of developing thermal stresses at t the joints.

References Cited in the file of this patent UNITED STATES PATENTS Meyer f July 21, Smith Feb. 8, Jarvis et al Nov. 15, Longfellow Sept. 17, Jackson Nov. 16, Menough July 1, Clark Mar. 20,

FOREIGN PATENTS Great Britain Apr. 26,