US2954222A

US2954222A - Work supporting fixture

Info

Publication number: US2954222A
Application number: US846422A
Authority: US
Inventors: Richard L Evans
Original assignee: SYRACUSE HEAT TREATING CORP
Current assignee: SYRACUSE HEAT TREATING CORP
Priority date: 1959-10-14
Filing date: 1959-10-14
Publication date: 1960-09-27
Anticipated expiration: 1977-09-27

Description

P 1960 R. L. EVANS 2,954,222

WORK SUPPORTING FIXTURE Filed Oct. '14, 1959 INVENTOR.

R/bhard L. Evans 2.5mne# ATTORNEY wry" United States. Patent of 2,954,222 WORK SUPPORTING rnrrunn Richard L. Evans, Onondaga, N.Y., assignor to cuse Heat Treating Corp., Syracuse, N.Y., a corporation of New York Filed Oct. 14, 1959, Ser. No. 846,422

1 Claim. (Cl. 266-6) This invention relates to a work holding or supporting fixture for supporting a plurality of work pieces during a hardening process. The particular process referred to comprises the heating of the work pieces to a temperature of 1500 Fahrenheit in a neutral salt bath for from 8 to 10 minutes. Thereafter the work pieces are quenched for from 2 to 4 minutes in a neutral salt bath at a temperature of from 350 to 400 degrees Fahrenheit. Thereafter the work pieces are air-cooled for one minute and finally whereby the rings are loosely received in the slots 18 but atv the same time are prevented from distorting during the work hardening process. I

The width of the slots 18 with relation to the thickness ofthe Work piece 20 has been found to be critical in that the slots must be sufficiently oversize, that is, greater than are washed in a tank of boiling water containing a suitable detergent. Prior to this time all previous methods of racking or supporting the work pieces during this operation or process have resulted in giving work pieces which may have achieved a suitable hardness but exceeded the maximum allowable distortion limit of 1%. That is, if more than one piece in a hundred distorted beyond a certain predetermined limit the work pieces were not considered acceptable.

Accordingly, it is an object of this invention to provide a work supporting fixture for supporting a plurality of work pieces during a work hardening process in a manner which permits the hardening of the work pieces but yet at the same time prevents distortion of the work pieces beyond a maximum allowable limit.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

In the drawings- Fignre l is an elevational view of the work supporting fixture embodying the invention shown with a plurality of work pieces supported thereon.

Figure 2 is an enlarged fragmentary view of a portion of the device shown in Figure 1.

The work supporting fixture comprises a center post 10 formed at its upper end with a hook 12 to permit the fixture to be supported during the work hardening process.

The center post-10 is provided with a plurality of sets of radially outwardly extending arms 14 positioned in spaced distances apart along the center post 10. "Each of the arms is provided along its lower edge with a strengthening rib 16 to prevent distortion of the arm 14 by reason of the work hardening process. Referring to Figure 2, it will be seen that each of the arms 14 is provided along its upper edge with a plurality of vertically extending slots 18 in which the work pieces, shown in the drawings to be annular rings 20, are received. The slots 18 are formed at their upper ends with tapered

side wall portions

22 and 24 to facilitate the loading of the rings 20 in the slots 18. Each of the slots extends into the arm 14 a depth at least equal to, or greater than the radial width of the ring 20 whereby to securely receive the ring 20 within the slot 18. The width of the slots 18 is slightly greater than the thickness of the ring 20 the thickness of the work piece, to permit the heating and quenching mediums to freely circulate over the areas of the work piece held between the side walls of the slots in order to satisfactorily work harden those areas of the work piece. At the same time, however, the width of the slots 18 cannot be too great as this would permit considerable movement of the work pieces within the slot and this movement will in turn result in distortion of the work piece. As best seen in Figure 2, the slot is sufficiently wide with respect to the thickness of the work piece to permit the free circulation of the heating and quenching mediums but at the same time the Width of the slot is not so great as to permit any great angular movement or deflection of the work piece in the slot 18.

In practice, where the thickness of the work piece 20 was twenty-two thousandths (.022) the optimum slot width was found to be twenty-nine thousandths (.029). In like manner where the thickness of the ring was twenty-eight thousandths (.028) the optimum slot width was found to be thirty-five thousandths (.035). While it will be thus seen that in. each case the width of the slot was seven thousandths (.007) oversize or greater than the thickness of the workpiece, it was determined that the width of the slot in relation to the thickness of the work piece had a critical range of from three to ten thousandths (.003 to .010) greater than the thickness of the work piece. Where the width of the slot in relation to the thickness of the work piece exceeded the upper limit of this range, it was found that the circulation of the heating and quenching mediums during the work hardening process and the movement of the rack or fixture caused angular deflection of the work pieces within the slots which resulted in distortion of the work pieces thus rendering them unacceptable. Conversely, where the width of the slot in relation to the thickness of the work piece was less than the minimum set forth in the range above, there was not sufficient space between the size of the slot and the work piece to permit the circulation of the heating and quenching mediums over the areas of the work piece held between the side walls of the slot. This resulted in a work piece having an area in the form of a radial line on each side which was not sufiiciently hardened due to the lack of circulation of the heating and quenching mediums as just described.

As will be obvious, a ring 20 is mounted in each of the slots 18 and the thus loaded fixture is supported by the hook 20 first in the heating bath and then in the quenchingbath, as previously described.

As will be obvious, the fixture comprising this invention is relatively simple and economical to manufacture and use but yet has resulted in supporting the work pieces 20 during the carrying out of the work hardening process in a manner whereby the work pieces are given the desired hardening without distorting beyond a maximum allowable limit.

What I claim is:

In combination, an annular work piece rectangular in cross section and a fixture for supporting a multiplicity of work pieces during the heat treatment thereof in a bath, said fixture comprising a vertical support, a rigid arm extending horizontally from said support, said arm being formed along its upper edge with a plurality of spaced apart slots, said slots extending downwardly from the upper edge of said arm a distance at least equal to the radial dimension of the annulus of said annular Wolf};

Patented sept 27,1960

piece, each of said slots having a width 25 to 35 percent greater than the axial thickness of the work piece.

References Cited in the file of this patent 1 UNITED STATES PATENTS Weyel -1 Aug. 7, 1923 Armstrong Sept. 21,.1926 Jackson Nov. 20, 1934 Maibauer June. 1, 1943