US2290546A

US2290546A - Apparatus for heat treating steel stamp blanks

Info

Publication number: US2290546A
Application number: US341926A
Authority: US
Inventors: Larry D Donbeck
Original assignee: Individual
Current assignee: Individual
Priority date: 1940-06-22
Filing date: 1940-06-22
Publication date: 1942-07-21
Anticipated expiration: 1959-07-21

Description

y 1942- L. D; DONBECK 2,290,546

APPARATUS FOR HEAT TREATING STEEL STAMP BLANKS Filed June 22, 1 940 [now afar: zflem 0. DOA/BECK,

Patented July 21, 1942 UNiTE; S-TTES V APPARATUS FOR HEAT TREATING STEEL STAMPBLANKS Larry'D'. Donbeck, Gary, Ind. Application June 22, 1940, Serial No.341fl26 2 Claims. (01. 266-6) This invention relates to improvements in apparatus for the quenching of steel articles to provide the same with both hardened and ductile portions.

For example, in the manufacture of steel stamps, it is customary to harden the blanks to .be -used therefor and to provide ductile end por- My invention contemplates the production of such steel articles havin the desired hardened and ductile portions by apparatus enabling the control of the formation of the ductile portions as to the extent and degree thereof.

I further have in view the provision of apparatus capable of such controlled treatment for a plurality of articles to produce the same with a high degree of uniformity.

Additional objects and advantages will become apparent from the following description taken in connection with the accompanying drawing, wherein:

Fig. 1 is a top plan view of a quenching fixture employed in the practice of my invention;

Fig. 2 is a top plan view thereof; and

Fig. 3 is an enlarged detail section taken on the line III-III of Fig. 1.

Referring to the drawing, a designates a series of steel stamp blanks or the like whose shank portions are to be hardened and one terminal portion of each of which is to be rendered soft and ductile for the subsequent cold working of the latter. The blanks a are preformed of rectangular, square, round or other desired crosssection, and are preferably of eutectoid or hypereutectoid steel containing from substantially .85% to 1.10% carbon.

From the standpoint of commercial production as well as for uniformity, it is desirable to treat a plurality of the blanks a in a single operation, as for example, by heating and quenching a plurality thereof simultaneously. In addition, it is desired to uniformly control the cooling of those portions of the blanks a which are to -be rendered soft and ductile.

For these purposes, I provide aquenching 'fi-X- ture 5 comprising a metal body of convenient configuration. While I have shown the fixture .in the form of a ring, other shapes may be employed so long as they embody the physical characteristics hereinafterset forth.

The quenching fixture 5 includes a plurality of sockets fi having a configuration corresponding to the cross-section of the-blanks a, and havinga'dequate depth to receive and retain the ends of the series of blanks with their shanks or major portions of their lengths freely projecting above the fixture.

The fixture -5 thus provides :anadded mass "of metal, such as steel, surrounding the end portion of each blank a, servin to influence the rate of heat transfer from the blanks during quenching -of the -same, which influence'alfects the hardenability of the blanks. This'condition or influence may be designated as a mass effect, by which I am enabled to produce the results and advantages desired in respect to controlling the ductility of the end portions of the blanks, While permitting the hardening of their shank portions.

The sockets 6 containing the ends of the blanks a are spaced apart a sufficient distance to provide a substantial mass of metal surrounding the same, the spacing also being sufficient to permit free circulation of a quenching medium about the shanks of the blanks upon immersin the fixture and blanks in a quenching bath. Said spacing also prevents any interference with the quenching action due to the combined heating effect of adjacent blanks.

The fixture 5 and its contained blanks a are heated to a temperature Within the thermal critical range of the steel of the blanks, which temperature in the case of the eutectoid and hypereutectoid steels preferred may be between approximately 1380 F. and 1450 F., and the fixture and blanks are then quenched together in cold water.

The rapid and unimpaired cooling of the free shank portions of the blanks a hardens the same to the desired degree of hardness, whereas the mass effect of the fixture 5 retards the cooling of the inserted end portions of the blanks sufficiently to permit a direct transformation of the unstable austenite into pearlite, whereby said end portions will have the desired ductility.

In other words, the mass effect of the fixture provides a time phase during the. cooling of the end portions of the blanks, permitting such a transformation to take place.

The foregoing method and apparatus permit positive and accurate control of the ductility of the end portions of the blanks or articles bein treated, both as to the degree and extent of said ductility. Thus, the mass effect of the fixture may be controlled by the mass or size thereof, thereby controlling the time phase of the treatment and hence the degree of ductility obtained. Also, the depth of the sockets 6 may be varied to correspondingly vary the length or extent of the ductile portions produced.

These factors, together with the spacing of the sockets also provide for uniformity of the resulting product, both as to their hardened and ductile portions. The said uniformity is also promoted by the ring form of the fixture, the same tending to a more uniform heating and cooling as well as providing uniformity of heat transfer between the plurality of blanks and the fixture.

With further reference to the spacing and orientation of the sockets 6, I prefer to position sockets for blanks of rectangular or square crosssection in corner-to-corner relation, as shown in the drawing, thus minimizing the heating effect between adjacent blanks and insuring thorough and complete quenching throughout the free portions of the blanks.

For the purpose of furthering the control. of the characteristics of hardness and ductility in the blanks by means of my invention, I prefer to employ a steel of the type stated whose cementite is in spheroidized form. While steel whose cementite is in either lamellar or spheroidized form may be employed, I have found that the latter produces superior results for present purposes when heated and quenched in the manner set forth herein, the spheroidized form tending to a lower hardenability.

Spheroidized cementite tends to be more sluggish than the lamellar form in going into solid solution, and since the cold workability of the steel is enhanced by not throwing all the carbon into solid solution, the said form enables the production of a high degree of ductility by the present heat treatment. Further, it is thought that a steel whose cementite has been spheroidized is more adaptable to the control factors applied by the present invention.

Suitable means may be employed for immersing and withdrawing the quenching fixture 5. For example, I designates a supporting spider having a lifting eye 8 projecting therefrom and above the fixture.

Various changes and modifications are contemplated within the scope of the following claims.

I claim:

1. A quenching fixture for the heat treating of rectangular high carbon steel stamp blanks including a metallic ring having an annular series of sockets therein of rectangular cross-section and arranged in corner-to-corner relation, said sockets being equally spaced within the confines of the ring and spaced apart to provide a sufficient mass of the ring about each socket to uniformly control and retard the rate of heat transfer from those portions of the stamp blanks enclosed by the sockets, upon heating the blanks and fixture and then quenching the same with the blanks in said sockets.

2. A quenching fixture for the heat treating of high carbon steel stamp blanks and the like, including a unitary metal body having a series of spaced sockets therein for receiving and enclosing the end portions of said blanks and the like, the spacing of all of the sockets with respect to the confines of the body and with respect to each other providing a mass of the metal of the body about each socket to eifect a substantially uniform retarded cooling of the blank end portions in each of said sockets upon heating and then quenching the blanks and fixture together.

LARRY D. DONBECK.