US3607464A - Treatment of elongated high speed steel members after austenitizing - Google Patents
Treatment of elongated high speed steel members after austenitizing Download PDFInfo
- Publication number
- US3607464A US3607464A US761365*A US3607464DA US3607464A US 3607464 A US3607464 A US 3607464A US 3607464D A US3607464D A US 3607464DA US 3607464 A US3607464 A US 3607464A
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- members
- broach
- cooling
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- zones
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/28—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for plain shafts
Definitions
- This steel is hardened by heating the member throughout to approximately 2200 F., then cooling it in oil or salt to an appropriate temperature as for example 600 F800 F. (for oil), after which the member is permitted to air cool.
- the air cooling during which the member hardens, the broach or other high speed steel member, even if initially straight'when removed from the furnace, undergoes unpredictable distortion which may be relatively great and far beyond acceptable limits.
- elongated members of this type were straightened during cooling by noting eccentricity or warpage, as for example by rotating the members between centers, and repeatedly reverse bending the members at the points of greatest eccentricity during cooling so as to produce an acceptably straight part.
- members of this type are ordinarily tempered two or three times by heating to an appropriate tern perature, as for example l,O F., and again permitted to air cool to room temperature. As the elongated members cool, further distortion takes place and the members are straightened repeatedly during cooling by reverse bending as required.
- an appropriate tern perature as for example l,O F.
- FIG. 1 is a perspective view of apparatus employed in carrying out the present method.
- FIG. 2 is an enlarged elevational view of a steady rest employed on a lathe bed as seen in FIG. ll.
- FIG. 3 is a side elevational view of the steady rest shown in FIG. 2.
- an initially straight bar acquires interior stresses and relieves machining stresses, which result in bending, distortion or warping of the bar. This occurs in an entirely unpredictable manner.
- the bar may during cooling exhibit a uniform bow from end to end. Conversely, it may become S-shaped. In other cases the distortion may appear in different planes so that the bar has a helical distortion.
- a method is employed in which concentrically is maintained only during a critical phase of air cooling following partial cooling from austenitizing temperature.
- broach parts made of M2 steel have been heated to approxi mately 2,200 E, after which they have been quenched in oil to approximately 600-800 or in salt up to 1,050".
- the part is brushed to remove dirt, this operation also removing a copper layer commonly provided by painting prior to initial heating.
- the elongated tool steel part is then set up between centers and rotated on its axis.
- eccentricity or runout which is due to bending or distortion of the part and which occurred during initial cooling, is noted by indicator.
- the zones of maximum curvature or eccentricity are marked.
- rigid steady rest devices which will subsequently be described in detail, are moved into registration with the zones of maximum distortion and are otherwise uniformly positioned along the length of the member at distances which depend upon the dimensions of the part but which may conveniently be from a few inches to two feet or more.
- These steady rests are moved inwardly simultaneously to engage the high-speed steel member on accurately finished cylindrical surfaces and sufficiently pressure is applied to maintain concentricity of these cylindrical bearing surfaces during continued rotation of the member for a predetermined temperature range during cooling. Cooling is accelerated by directing currents of air preferably at ambient room temperature, over the member. By this step, total time of cooling is materially reduced, and attention of an operator to periodically straighten the member is not required.
- FIG. 1 there is illustrated apparatus for carrying out the method.
- a lathe indicated generally at having a driving headstock 12 including a chuck 14 adapted to engage one end of the elongated high-speed steel member M and to drive it in rotation.
- the other end of the member M is engaged by a center 16 of a tailstock l8.
- the lathe 10 is operated to drive the member M in rotation and suitable gauge means are moved along the member M to note the amount and location of distortion.
- the steady rests indicated generally at 20, are moved into engagement with the opposite sides of the member, the steady rests being moved axially of the member if desired to insure location of the steady rests at the point of maximum distortion.
- FIGS. 2 and 3 details of the steady rests are shown.
- Each of the steady rests is mounted on base 22 which is movable along ways provided on the bed of the machine and the supports 22 may be firmly clamped in position by suitable means such as the clamp bars 24.
- Mounted on transversely extending dovetail ways indicated at 26 on each of the supports 22 are a pair of slides 28 and 30, these slides being interconnected by a screw shaft 32 having right-hand screws indicated at 34 and left-hand screws indicated at 36 for causing simultaneous approach and separation between the slides 28 and 30 on rotation of the screw shaft by application of a suitable tool to the squared end 38 thereof.
- each of the slides 28 and 30 Extending upwardly from each of the slides 28 and 30 is a rigid column 40 carrying a roll support 42 provided with a pair of rolls 44 and 46.
- the roll supports 42 are held against the inner surfaces 48 of the column 40 by means including the clamping screw 50.
- a master bar is mounted on the lathe between centers and the slides 34 and 36 are moved inwardly until the rolls 44 and 46 of both supports 42 engage the bar. If engagement occurs between the pair of rolls at one side of the bar prior to the pair of rolls at the other side, the appropriate slide 28, 30 is shimmed to insure exact simultaneous engagement of all four rolls.
- a tie bar 52 is provided which is pivoted as indicated at 54 to one of the columns 40 and which has a threaded portion 56 received in a slot provided at the top of the other column.
- a clapping nut 58 is provided on the thread portion which may be tightened to insure maintenance of exact concentricity of the portion of the elongated high-speed steel member engaged by the rolls 44 and 46.
- the broach or other member after cleaning and mounting in the lathe and checking to determine distortion, will have cooled usually to a temperature substantially below 600.
- the present method is limited to maintenance of concentricity within practical limits only during a predetermined temperature range of air cooling following initial cooling after the member has been brought to its relatively high austenitizing temperature. During subsequent air cooling following tempering or draw operations, the present method is not employed and the member is maintained with the required straightness by the reverse bending techniques which has previously been employed. It is to be noted however, that this reverse bending technique as applied during the repeated tempering operations is rendered much easier to perform than when the initial hardening operation included manual straightening by reverse bending.
- the rate of rotation of the elongated member during the maintenance of concentricity need not be great and excellent results have been obtained when the rate of rotation was at 25 r.p.m., the slowest speed at which a lathe on which the operation has been performed can be run.
- the speed of rotation is evidently not critical but should be between about l0 r.p.m. and a few r.p.s.
- EXAMPLE In the following examples, the procedure used was as follows: The elongated members were brought up to the appropriate temperature as for example 2,200 F., and were quenched in oil to the temperature noted. The parts were removed from the oil and placed between centers on a machine with adjustable steady rests about 12 inches apart. The members were rotated at 25 r.p.m. and the steady rests tightened. The members were allowed to cool from the temperatures listed as straightening temperature (Straightening Temperature) to 125 F. and sometimes to ambient temperatures and then put in the tempering furnace and the regular heat-treating cycle was continued, with the results noted.
- straightening temperature Stringening Temperature
- the invention is applicable generally to air-hardening tool steels. These steels are heated throughout to austenitizing temperature in excess of 2,000 F. and are then ordinarily cooled as for example by quenching in oil or salt to much lower temperatures, for example 600-800 P. if quenched in oil. At these temperatures the material of the elongated members is still plastic and appreciable hardening has not commenced. As these steel thereafter are allowed to cool relatively slowly in air, the hardness increases and it is during this stage of cooling that distortion occurs.
- the steels to which the present invention is applicable may be described generally as air hardening tool steels including high-speed tool steels.
- the steels to which the present invention is applicable are A2-l0; D l-7; l-ll026, 41- 43;Tl9,l5;Ml-4,6-8,10,15,30, 33-36,4l-44.
- the present method of maintaining concentricity by the roll steady rests eliminates all of the man hours involved in straightening the elongated member out of quench. All that is required is for the operator to place the member in the machine, tighten the roll steady rests, and start the member rotating.
- the method apparently results in the elongated members being straightened relatively stress free in that the runout developed after the first tempering operation is reduced substantially compared to runout which would be anticipated without practice of the present invention.
- the invention is applicable to any size part, but its advantages are best realized with larger parts, as for example 36- inch or longer and about 2-inch diameter or more. This is due in part to the fact that on smaller parts which cool more rapidly, the man hours required to maintain straightness by conventional processes are substantially less than on larger parts.
- cooling may include any recognized quenching operation such as cooling oil, in salt followed by air cooling to room temperature, or even air cooling alone.
- the method of treating elongated members of air-hardening tool steel having aplurality of longitudinally spaced axially aligned annular zones thereon which comprises heating the members throughout to austenitizing temperature, cooling the members to a predetermined intermediate temperature between 600 and 150 F. without checking or maintaining straightness, and thereafter air cooling the members at least to F. while maintaining a plurality of axially spaced zones of said members in substantially exact concentricity during cooling throughout the air hardening range by the step of supporting annular zones on the members in concentric aligned positions between supports mounted in fixed position and rotating the members.
- each of said supports comprises at least three rollers.
- the method of claim 1 which comprises the step of directing a current of cooling air at room temperature against the members during cooling thereof.
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- Heat Treatment Of Articles (AREA)
Abstract
Description
Claims (17)
- 2. The method of claim 1 in which each of said supports comprises at least three rollers.
- 3. The method of claim 1 which comprises the step of directing a current of cooling air at room temperature against the members during cooling thereof.
- 4. The method of claim 2 which comprises the step of directing a current of cooling air at room temperature against the members during cooling thereof.
- 5. The method of claim 3 which comprises initiating the maintenance of concentricity at a temperature between 425* F. and 225* F.
- 6. The method of claim 5 which comprises continuing the maintenance of concentricity to a temperature near 125* F.
- 7. The method of claim 5 which comprises discontinuing the maintenance of concentricity at room temperature.
- 8. The method of claim 3 which comprises rotating the members at a speed of between 10 r.p.m. and a few r.p.s.
- 9. The method of claim 1 which comprises thereafter tempering the members and straightening them to maintain the required tolerance by reverse bending during cooling.
- 10. The method of claim 1 which comprises indicating eccentricity of the members during initial rotation, and applying the maintenance of concentricity at the zones initially exhibiting maximum eccentricity.
- 11. The method of claim 1 in which said members are formed of alloy steels selected from the group consisting of M2, M3 and T1.
- 12. The method of claim 1 in which said members are formed of M2 alloy steel.
- 13. The method of claim 11 in which said members are broaches.
- 14. The method of claim 12 in which said members are broaches.
- 15. The method of claim 4 in which said members are short, and in which said rollers have their axes parallel to the length of the members and support the members without axial advance until their temperatures fall to about 125* F.
- 16. The method of heat treating an elongated broach of generally circular cross section having at longitudinally spaced zones therealong a plurality of axially aligned annular zones, the broach being formed of an air-hardening steel alloy selected from the group consisting of T1, M2 and M3, the method comprising the steps of heating the broacH throughout to tis austenitizing temperature in excess of 2,150* F. cooling the broach to an intermediate temperature between 600* F. and 150* F. without checking or maintaining straightness, thereafter supporting the broach with the annular zones maintained in exact axial alignment by sets of at least three rollers in contact with each of a plurality of selected annular zones, said rollers having their axes parallel to the length of the broach, rotating the broach by rotating one or more of said rollers, directing a current of cooling air over substantially the entire surface of said broach during its rotation by said rollers, and continuing the maintenance of aligned rotation, and the direction of cooling air against the broach until its temperature has fallen to a temperature between 125* F. and room temperature, and thereafter tempering said broach in a tempering operation in which the straightness of the broach is maintained within limits during air cooling by reverse bending.
- 17. The method as defined in claim 1 which comprises mounting the members for rotation on a fixed axis after cooling to the aforesaid intermediate temperature, rotating the members to determine zones of maximum eccentricity, and positioning at least some of the supports longitudinally of said members into substantial registration with zones of maximum eccentricity.
- 18. The method as defined in claim 16, which comprises mounting the broach for rotation on a fixed axis after cooling to the aforesaid intermediate temperature, rotating the broach to determine zones of maximum eccentricity, and positioning at least some of the sets of rollers longitudinally of the broach into substantial registration with zones of maximum eccentricity.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US76136568A | 1968-07-10 | 1968-07-10 |
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US3607464A true US3607464A (en) | 1971-09-21 |
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US761365*A Expired - Lifetime US3607464A (en) | 1968-07-10 | 1968-07-10 | Treatment of elongated high speed steel members after austenitizing |
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5123465B1 (en) * | 1971-07-05 | 1976-07-16 |
-
1968
- 1968-07-10 US US761365*A patent/US3607464A/en not_active Expired - Lifetime
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5123465B1 (en) * | 1971-07-05 | 1976-07-16 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: ADD, INC., A MICHIGAN CORP.,STATELESS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LEAR SIEGLER, INC. A DE. CORP.;REEL/FRAME:004600/0061 Effective date: 19860530 Owner name: ADD, INC., A MICHIGAN CORP. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:LEAR SIEGLER, INC. A DE. CORP.;REEL/FRAME:004600/0061 Effective date: 19860530 |
|
AS | Assignment |
Owner name: NATIONAL BROACH & MACHINE COMPANY, Free format text: CHANGE OF NAME;ASSIGNOR:ADD, INC.;REEL/FRAME:004664/0771 Effective date: 19860708 |
|
AS | Assignment |
Owner name: RAO, SURENDRA B. Free format text: SECURITY INTEREST;ASSIGNOR:NATIONAL BROACH & MACHINE COMPANY;REEL/FRAME:005033/0527 Effective date: 19880928 Owner name: FERRETT, JAMES A. Free format text: SECURITY INTEREST;ASSIGNOR:NATIONAL BROACH & MACHINE COMPANY;REEL/FRAME:005033/0527 Effective date: 19880928 Owner name: WILKINS, LEONARD J. Free format text: SECURITY INTEREST;ASSIGNOR:NATIONAL BROACH & MACHINE COMPANY;REEL/FRAME:005033/0527 Effective date: 19880928 Owner name: DONNELLY, JOHN T.; Free format text: SECURITY INTEREST;ASSIGNOR:NATIONAL BROACH & MACHINE COMPANY;REEL/FRAME:005033/0527 Effective date: 19880928 |
|
AS | Assignment |
Owner name: NATIONAL BROACH & MACHINE COMPANY Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. SECURITY AGREEMENT RECORDED AT REEL 5033 FRAME 0527;ASSIGNORS:DONNELLY, JOHN T.;WILKINS, LEONARD J.;FERRETT, JAMES A.;AND OTHERS;REEL/FRAME:005639/0406 Effective date: 19910312 |