US3294597A

US3294597A - Method for quenching a metal member

Info

Publication number: US3294597A
Application number: US484508A
Authority: US
Inventors: Gerald J Kuchera
Original assignee: AO Smith Corp
Current assignee: AO Smith Corp
Priority date: 1960-12-05
Filing date: 1965-08-04
Publication date: 1966-12-27
Anticipated expiration: 1983-12-27

Description

Dec. 27, 1966 G. J. KUCHERA METHOD FOR QUENCHING A METAL MEMBER Original Filed Dec. 5, 1960 6 Sheets-Sheet l INVENTOR. Gena/J I (QC M2 1?- BY Jr:

Deb. 27, 1966 G. J. KUCHERA 3,294,597

METHOD FOR QUENCHING A METAL MEMBER Original Filed Dec. 5, 1960 6 Sheets-Sheet 2 FIG. 6.

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(mun INVENTOR. Qera/d J. Kuchera BY 71127118 I! jl drr Dec. 27, 1966 G. J. KUCHERA METHOD FOR QUENCHING A METAL MEMBER Original Filed Dec. 5, 1960 6 SheetsSheet 5 FIG. 5.

I IN VENTOR gerald J. Kuchera BY flndrvs fff'd k'e differ/legs Dec. 27, 1966 5. J. KUCHERA 3,294,597

METHOD FOR QUENCHING A METAL MEMBER 5, 1960 v 6 Sheets-Sheet 4 Original Filed Dec.

INVENTOR.

g erald J. Kuchera BY nab-us Sidr-Kg #Ifforneys Dec. 27, 1966 G. J. KUCHERA 3,

I METHOD FOR QUENCHING A METAL MEMBER Original Filed Dec. 5. 1960 6 Sheets-Sheet 5 FIG. 8.

uvmvron. Qewa/J I Kuc/zua Dec. 27, 1966 G. J. KUCH ERA METHOD FOR QUENCHING A METAL MEMBER 6 Sheets-Sheet 6 Original Filed Dec. 5, 1960 FIG. I2.

FIG. 13.

INVENTOR. f a/ .f/(uc zema BY eflnJ -us f Sfdrli'e bfffome s lumluuu Patented Dec. 27, 1966 3,294,597 METHOD FOR QUENCHING A METAL MEMBER Gerald J. Kuchera, Milwaukee, Wis., assignor to A. 0. Smith Corporation, Milwaukee, Wis., a corporation of New York Original application Dec. 5, 1960, Ser. No. 73,954, new Patent No. 3,252,695, dated May 24, 1966. Divided and this application Aug. 4, 1965, Ser. No. 484,508 1 Claim. ((31. 148-131) This application is a division of application Serial No. 73,954, filed December 5, 1960 now Patent No. 3,252,695 and entitled Apparatus for Quenching a Metal Member.

This invention relates to metal processing, and, more particularly, to a method of hot straightening and quenching long channel members for use as truck trailer side rails.

In the past, the quenching and subsequent straightening of long channel members has been almost a completely manual operation. The channel members for truck trailers range in length from 25-40 feet, and are first heat treated, and then quenched to obtain the necessary tensile strength and hardness required in the frame of a truck trailer without unduly increasing the weight of the frame, and thereby increasing the payload which may be carried under the gross weight limit laws for state and federal highways. The heat treatment causes considerable non-uniforrn warpage, twist and bow because the channel member expands unequally during heating. All warp, twist, and bow must be removed and pairs must be matched in length before the channel member is acceptable for use as a truck trailer side rail.

Prior to the development of the present invention, the channel members Were heat treated, quenched in oil, and cold straightened manually. After the channel member was heated to about 1650 F. in a heat treating furnace, it was removed manually, and placed in an oil quench tank for about 30 seconds. When removed from the oil quench, the cooled channel member usually was badly distorted in bend, twist and bow. At this point, a team of four specially skilled straighteners would check the channel member with gages for bend, twist, camber, and combinations thereof. With the aid of hydraulic presses and primitive straightening bars, the straightening team manually removed all indicated excess bend, twist, bow and camber from the channel member. It was also necessary to redrill bolt holes if the channel member had expanded unevenly. The manual straightening of the large channel members was an expensive, time-consuming operation, fraught with considerable hazard because of the necessary handling of the red hot steel channel member during the manual oil quenching operation.

This invention provides a completely automatic means to hot straighten the channel member to remove all bend, twist, bow and camber, and then die-quench it to obtain a straight channel member having the required tensile strength and hardness. The complete operation takes about one minute as compared to the manual .oil quench and subsequent manual straightening process which consumed as much as five -manhours. Another important advantage of this invention is that channel members of uniform length are produced because of the uniform, allover quenching efiect of the quenching apparatus. Consequently, any two members may be matched as a pair and, further, it is generally not necessary to redrill bolt holes which are pierced during the initial forming prior to heat treating and die-quenching.

This invention is directed to a large, segmented diequench machine which first hot straightens and subsequently die-quenches a long channel member. The appar-atus is a longitudinal series of die assemblies which are adapted to receive a heated channel member, straighten it, and then rapidly quench it with fast flowing water to produce a straight channel member having improved physical properties.

The rapid quench is made possible by causing a high rate of cooling water to flow out through a network of passages in the die assemblies, and directly into contact with the channel member being quenched. The water passages through the surfaces of the die assemblies are uniformly spaced and therefore, the water flow provides uniform quenching action on all surfaces of the channel member.

An important feature of the apparatus of the invention is use of a series of movable die sections which move to maintain a selected holding or gripping'of the shrinking hot channel member during quenching. All of the die surfaces which are in contact with the channel member are adapted to collapse inwardly towards a central reference point and hold contact with the same specific portion of the channel member as it shrinks to the cold or quenched dimensions. If the die surfaces did not collapse with the shrinking channel member, irregular stresses would be set up by the restraining action of the die surfaces on specific portions of the channel member, Warping would result, and a channel member having uniform physical properties throughout its length could not be obtained.

To accomplish the necessary collapsing motion of the die sections, each one of the longitudinal series of male dies is pivotally mounted on a sliding ram plate on levers which are adapted to swing through an arc in the direction of the length of the die-quench machine, thus following the channel member as it shrinks in length.

The longitudinal series of female dies in which the channel member is disposed during quenching are also adapted to move longitudinally and laterally to allow for shrinkage of the channel member during quenching. The female dies are each divided into three parts. All the parts of the female die are supported on a die shoe, which is disposed on rollers to provide for limited horizontal motion of each female die section along the length of the die quench machine. The bottom and one sidewall of the female die are directly bolted to the die shoe, but the third part is also adapted to move laterally, being connected to the die shoe through a tandem cylinder arrangement. This third part, referred to as the movable sidewall, follows the lateral shrinking of the channel member.

All surfaces of both the male and female dies which contact the channel member have a network of open passages which give the die surfaces a wafile-like appearance. The dies each have a system of internal passages which communicate with the wafile-like surfaces. To quench the channel member, a cooling medium such as water, is supplied to the surfaces of both the male and female die members which are disposed in contact with the channel member. A small space is provided between each die section in the series so that each die section is free to move with the channel member as it shrinks longitudinally during cooling.

In operation, the red hot channel member is transferred, web down, into the female dies of the series of die sections. The movable sidewall of the female die is then moved in, clamping the hot channel member between fixed and movable sidewalls of the female die sections, thereby hot straightening the channel member.

The expandable male dies are then moved toward the female die members and into the channel member throughout its length and expanded laterally into engagement with the side flanges of the channel member. The female dies press against the outer surfaces of the channel member while held from the inside by the male dies, firmly clamping the channel member. Quenching water is then circulated under pressure through the cooling system, and cooling water flows abundantly out through the network of intersecting passages in the male and female die surfaces, and into direct contact with all surfaces of the red hot channel member. The flow of cooling water through the uniformly distributed passages quenches the channel member rapidly and uniformly while it is being held by the die assemlies. The male dies are then withdrawn from the quenched channel member, the female die is expanded, and an unloader mechanism ejects the channel member from the quench machine. After stress relieving the quenched channel member, it exhibits greatly improved tensile strength and hardness, such as are required for structural elements in a truck trailer.

In the drawings:

FIGURE 1 is a side elevation of the apparatus of the invention with the water pit shown in section;

FIG. 2 is a side elevation of the die-quench machine with a channel member positioned therein;

FIG. 3 is a perspective view of the channel member which is quenched in the apparatus of the invention;

FIG. 4 is a front elevation of the die-quench machine with parts broken away in section;

FIG. 5 is an enlarged transverse section showing the die assembly with a channel member disposed therein;

FIG. 6 is a vertical sectional view taken along line 66 of FIG. 5

FIG. 7 is a section taken along line 77 of FIG. 4 with parts deleted for clarity;

FIG. 8 is an enlarged front elevation of the male die assemblies in the hot channel member position;

FIG. 9 is an enlarged front elevation of the male die assemblies in the quenched channel member position;

FIG. 10 is an enlarged section taken along line 1010 of FIG. 2 with parts broken away;

FIG. 11 is a top elevation with parts broken away showing the tandem cylinder drive for the movable. sidewall of the female die;

FIG. 12 is an enlarged front elevation with parts broken away showing the gage adjustment assembly for the female die; and

FIG. 13 is an end view of the structure shown in FIG. 12 with parts deleted for clarity.

As shown in the drawings, the apparatus of the invention comprises a series of die-quench units 1 which are supported on a foundation 2. When used for quenching trailer side rails, the apparatus may include about 16 to die-quench units 1. A pit 3 is formed in foundation 2 and is disposed under the die-quench units 1. The pit 3 is adapted to receive the quenching liquid, preferably water, which is used to quench the side rail or other workpiece. A pair of shoulders 4 are disposed along the top of the pit 3 and a pair of long beams 5 extend the length of the pit 3, and are supported by the shoulders 4. Transverse beams 6 are supported on the beam 5 and a second pair of long beams 7 are supported on the transverse beams 6. The beams 7 support a series of vertical C- frames 3 which are disposed at regular intervals along the long beams 7. The C-frames 8 are tied together by a third pair of long beams 9 which are secured across the top of the C-frames 8 and rigidly anchor the C-frames in position.

A pair of bars 11) are mounted on the lower horizontal portion of each C-frame 8, and each bar 10 supports a pair of spaced brackets 11 and 12. The brackets 11 are bifurcated and are adapted to rotatably support rollers 13 while the top of each brackets 12 is wedge shaped when reviewed from the end and carries a pair of rollers 14. Each roller 14 is disposed to rotate on a diagonal axis and each pair or rollers 14 is adapted to ride on a wedgeshaped rail 15, while rollers 13 ride on a flat rail 16. Both the

rails

15 and 16 are mounted on the lower surface of a movable die shoe 16.

A female die 18 adapted to receive a channel member 19 to be quenched is supported by the die shoe 17. A base section 20 of the female die 18 is secured by bolts to a pad 21 which is disposed within a cavity in the die shoe 17. The female die 18 also includes a fixed sidewall 22 which is secured to the die shoe 17 by means of bolts and a movable sidewall 23, which is adapted to move laterally towards and away from the fixed sidewall 22. The inner surface 24 of the base section 20, the inner surface 25 of the fixed sidewall 22, and the inner surface 26 of the movable sidewall 23, are interlaced with a network of channels 27 which give a waflle-like appearance to the die surfaces.

The outer end of the movable sidewall 23 is secured to a platen 28 by a clamp 29 and the platen is adapted to be moved toward the fixed sidewall 22 of the female die 18 in a two stage movement by a hydraulic unit which includes a fixed cylinder 30 and movable cylinder 31. The outer head 32 of the fixed cylinder 30 carries a threaded rod 33 which is threaded in an opening in a ball 34 disposed in socket 35 and a pair of bushing members 36 mounted on a plate 37 are secured to opposite sides of the socket. The plate 37 is provided with a depending flange 38 which is attached to the side edge of die shoe 17 by bolts. The fixed cylinder 30 is also supported by a pair of spaced guide rails 39 secured to the upper surface of plate 37.

A pair of pistons 40 are mounted on a piston rod 41 and are slidably disposed in cylinder 30. The end of piston rod 41 is threaded and is engaged within an opening in the outer end of piston rod 42 while the rod 42 carries a pair of pistons 43 which are slidable within the movable cylinder 31. The piston rods 41 and 42 are connected together and move as a unit, and a nut 44 is threaded on the exposed end of rod 41 and provides an adjustment for the overall length of the piston rod unit.

The forward head of cylinder 31 carries a yoke 45 which straddles and is secured to a ball 46 by a vertical pin 47. The ball 46 is disposed within a socket 48 formed in the central portion of head 49 which extends generally parallel to platen 28. Each end of head 49 is bifurcated, as indicated by St), and is disposed between the rear surface of the platen 28 and an upstanding plate 51 which is connected to platen 28 by flange 52. With this construction both the platen 28 and movable sidewall 23 of the female die will move with the head 49.

The head 49 is guided in reciprocating motion toward and away from the fixed sidewall 22 by a pair of guide rods 53 which are secured within the bifurcated ends 50 of the head by pins 54. The outer ends of the guide rods 53 are journaled within bushing members 36 and a second pair of bushing members 55 support the central portions of guide rods 53 for sliding movement.

To activate the head 49, hydraulic fluid is introduced into cylinder 30 through

lines

56 and 57, and by introducing fluid into the rear of the cylinder through line 57 the pistons 40 and rod 41 will be moved forwardly. As the rods 41 and 42 are tied together, movement of rod 41 will result in a corresponding movement of rod 42 in cylinder 31. To provide a second increment of movement for head 49, hydraulic fluid is introduced into cylinder 31 through lines 58 and 59. By introducing fluid into the forward end of cylinder 31 through line 58 while maintaining the pressure in the rear of cylinder 30 through line 57, the cylinder 31 will be moved forwardly, with respect to the pistons 43, in a second increment of movement toward the fixed sidewall 22.

To begin operation the movable sidewall 23 is in the rearward or open position and the channel member 19 is positioned on the base section 20 of the die. By introducing fluid into cylinder 30 through line 57, the head is moved inwardly to bring the sidewall 23 into engagement with the outer surface of the flange of the channel member. During quenching, fluid is introduced into the cylinder 31 through line 58 to urge continuously the sidewall 23 against the flange and take up any lateral shrinkage of the channel member.

During the quenching operation, the channel member 19 will also shrink longitudinally and as the base section 20 and

sidewalls

22 and 23 of the female die are connected to the die shoe 17, which is slidable on

rollers

13 and 14, the die sections Will move with the channel member during shrinkage.

The pivotal attachment of the cylinder 38 to the plate 37 and the pivotal connection of the cylinder 31 to head 49 serves to compensate for any difference in alignment or axial movement between the tandem cylinder unit and the pair of guide rods 53.

The threaded connection of rod 33 and ball 34 serves as an adjustment for the spacing between the fixed sidewall 22 and the movable sidewall 23 when the sidewall 23 is in the closed position. By threading rod 33 in ball 34 the cylinder 30 will move on guide rails 39 to vary the size of the female die cavity as determined by the width of the channel member to be quenched.

A plurality of vertical stanchions 6 extend upwardly from the floor to an equal height just in front of the C-frames 8. The vertical stanchions 66 support an I-beam 61 which extends the entire length of the series of diequench units 1. A plurality of adjustment gage assemblies 62 are secured to the bottom of the I-beam 61 at intervals along its length, there being one adjustment gage assembly 62 for each die-quench unit 1.

Each adjustment gage assembly 62 is disposed below the I-beam 61 and is supported by means of a gage support bracket 63, which is bolted and welded to the I-beam. The gage support bracket 63 has a passage adapted to slidably receive one end portion of a gage rod 64, and a nut 65 and lock nut 66 are threadably attached to the end of the gage rod. The other end of gage rod 64 is threadedly attached to a die shoe bracket 67 which in turn is secured to the die shoe 17. A gage 68 is pivotally connected to the lower end of bracket 63 by bolt 69 and is free to rotate through an arc. Gage 68 has a jaw 70 in its free end for engaging a length of the gage rod 64 between the gage support bracket 63 and the nut 65. A pair of coil springs 71 are mounted in tandem on gage rod 64 between the die shoe bracket 67 and the gage support bracket 63. The springs 71 are held in place by means of springs collars 72 disposed at each end of each spring,

and the springs serve to urge the rod 64 and die shoe 17 to the left in FIG. 12 and thereby bias the nut 65 into engagement with the support bracket 63.

The gage 68 has a width equal to the calculated shrinktravel of each individual die shoe 17, and prior to the diequench operation, each gage 68 is pivoted up so that its jaw 78 engages a portion of the gage rod 64 between the gage support bracket and the nut 65 equal to the width of the gage 68. The nut 65 is screwed down on the gage rod 64, so that it is flush with the side surface of the gage 68, and at a distance equal to the width of the gage 68 from the gage support bracket 63. The lock nut 66 is then tightened down on the nut 65, and the gage 68 is pivoted down away from the gage rod 64, the coil springs 71 then urge the die shoe 17 to the left, biasing the nut 65 into engagement with the support bracket 63. The shrinktravel required for each individual die-shoe 17 must be calculated in advance, and increases progressively as the distance from the center of the machine increases. It is based on the relationship of the coefiicient of expansion to the anticipated increase in temperature and the distance of the individual die shoe 17 from the center of the machine.

Since the channel member 19 is first received in the machine at its hot dimensions, the die shoes 17 must initially be at their expanded position. Therefore, after the gage set-ups are made, the coil springs 71 move the die shoes 17 to their expanded positions to receive the hot channel member 19. The die shoes 17 then follow the shrinkage of the channel member to the quenched dimensions. If the die shoes 17 were not spaced as described, adjacent die shoes 17 would collide during shrinkage travel and cause unbalanced stresses in the quenched channel member 19.

A male die 73 is adapted to cooperate with the female die 18 and is slidably disposed above the female die so that it can be moved in and out of nesting relationship with the female die. The die 73 includes two similar male die sections 74 and 75 which have lateral surfaces 76 and bottom surfaces 77 which oppose the waflle-like surfaces 24, 25 and 26 of the female die when the male die is nested in the female die. The

surfaces

76 and 77 of the male die sections 74 and 75 are also interlaced with a network of channels 78, which are similar to the channels 27 on the female die surfaces and also give a waffle-like appearance to the

surfaces

76 and 77 of the male die sec tions.

The die sections 74 and 75 have dove-tailed central surfaces 7 9 to permit lateral expansion and contraction, and each male die section is slidably connected to a common Wedge 80 through a pair of pins 81 which project inwardly from ears 82 on the ends of the die sections. The pins 82 are slidably received in slightly larger diagonal slots 83 in the ends of the wedge 70. The axes of the slots 83 form a v when extended. As force is applied through the wedge 80 to the die sections 74 and 75, they tend to expand laterally and force the lateral surfaces 76 into contact with the inner surfaces of the flanges of the channel member 19.

Each wedge 80 has a pair of lugs 84 secured to the top surface thereof and each lug is pivotally connected to a link 85, which in turn is pivotally connected to a link 86. Link 86 has a keyed head 87 adapted to be received in a keyway 88 in the bottom of a platen 89 which is disposed above and generally parallel to the male die 73. A pair of shrink levers 90 and 91 are pivotally connected at one end to bosses 92 on the top surface of the platen 89 and the other end of each shrink lever is pivotally connected to a boss 93 on a movable ram plate 94. With this construction, the shrink levers 90 and 91 are free to pivot through an arc in a vertical plane along the axis of the series of die-quench units.

To guide the ram plate in vertical movement, the ram plate has beveled edges 95 on both sides thereof which are slidably disposed in a V-shaped groove 96 formed between the flange 97 on the C-frame 8 and gib 98 bolted thereto.

The pivotal connection of shrink lever 91 with ram plate 94 enables themale die 73 to move longitudinally and follow the shrinkage of the channel member 19 during quenching. Each male die is biased longitudinally outward from a normal hanging position at the start of the quenching operation by a coil spring 99.

One of the shrink levers 91 has a recess 100 for receiving one end of the spring 99 and the other end of the coil spring is disposed within a recess in the head 101 of a stud 102 which is threaded within an opening in a lug 103 on ram plate 94.

As shown in FIG. 8, the coil spring tends to bias the shrink levers 91 and, consequently, the male die 73, out from a normal hanging position below ram plate 94. FIG. 8 shows the die quench units 1 located on either side to remove the channel member from the female die.

of the machine during shrinkage of the channel member.

In addition, the shrink levers of each successive unit from 'the center line to the ends of the machine are biased outwardly away from the center line to permit each male die carried by the shrink levers to swing inwardly through a vertical position to a position toward the center line with the channel member as the channel member shrinks. The series of dies are spaced apart to permit each die to follow the channel member without interference from an adjacent die unit. The outward swing or displacement of the shrink levers 91 are limited by a gage rod 104 which is secured to one of the shrink levers 91 near its lower end. Gage rod 104 is slidably connected at its other end to a gage rod support 105 secured to the ram plate 94. An adjustable gage nut 106 threadably received on the end of the gage rod 104 limits the are through which the swing levers 91 are displaced by the spring 99.

A gage 107 is pivotally mounted on a gage bracket 108 on the platen 28 and is adapted to be inserted between the gage rod support 105 and the adjustable gage nut 106 to preset the initial limits of the arc through which the shrink levers 91 and the male die 73 will move during the quenching of the channel member 19.

The width of the gage 107 for each die-quench unit may vary depending on the initial displacement which is required for each male die 73. Normally the gage members 107 will have a progressively increasing width in a direction from the center line to the ends of the machine for the degree of shrinkage of the channel member is greatest at the end portions.

The ram plates 94 are each suspended through a pair of adjustable linkages 109 which connect the upper end of the ram plate 94 to one end of a large bifurcated lever arm 110, pivotally mounted on a bracket 111. The bracket 111 is secured to the two beams 9, which rest on the C-frames 8, as previously described. A cable 112 is secured to the other end of the lever ram 110 and the cable is also connected to a counterweight 113 to counter balance the weight of the ram plate 94 and male die 73. A long, continuous equalizer shaft 114 passes through each lever arm 110 and connects them so that they move together.

The ram plate 94 is driven up and down in the gibs 98 by means of a hydraulic drive mechanism 115 mounted on a pair of brackets 116, which are also secured to the plate 94 and the male die 73 to move into the female die.

When hydraulic pressure is reduced, the counterweight 113 acts on the lever arm 110 to cause the ram plate 94 and male die to move away from the female die and push the piston rod 117 back to its initial position.

After quenching, a knock-out mechanism is employed In this connection, several of the base sections 20 of the female die 18 and their respective die shoes 17 have vertical openings 120 extending through their central portions. Each opening 120 receives a knockout platen 121, which connects through a linkage 122 to one end of a knockout lever 123. The other end of the knockout lever is keyed to a knockout drive shaft 124, which extends the length drive means (not shown), the knockout platens 121 are raised or lowered together in relation to their respective female die base sections 20. The knock out platens 121 serve both to load and unload the die-quench machine.

The die-quench units 1 each have a water supply system to provide a large quantity of cooling water to each male die 73 and female die 18. Each die section 74 and 75 of the male die and

sidewalls

22 and 23 of the female die have central chambers 126 adapted to receive cooling water. The water is dispensed through openings 127 in die surfaces 24 and 25 of the female die and also through openings 128 in the cooperating surfaces of the male die.

Each male die section 74 and 75 has an inlet 129 communicating with the respective chamber 126 through which water is received from a plurality of outlet passages 130 in the wedge 80. Wedge 80 receives the water from a plurality of shortflexible hoses 131, which are threadably connected into passages 132 in the wedge. The inlet passages 132 communicate with a central passage 133 which in turn are connected to the outlet passages 130. The upper ends of the hoses 131 are connected to a pair of similar rigid manifolds 134 one being secured to the front and the other to the back of the ram plate 94. The manifolds 134 are each connected to flexible hoses 135 which connect at their other ends to a large rigid manifold 136 disposed in back of the C-frame 8. The manifold 136 is connected by a pipe 137 to pump 138, which pumps water under pressure up through pipe 139 from the pit 3.

Water is supplied to the die surface of base section 20 of the female die 18 through water inlet openings 127, which are aligned with outlet openings 140 in the die shoe 17. Die shoe 17 has a central chamber 141, which has a water inlet 142 and the water inlet is connected to a flexible hose 143 which extends down around the lower parts of the C-frame 8 to the manifold 136, described above.

Water is supplied to the chamber 126 of fixed sidewall 22 of female die 18 by means of a passage 144 which connects the chamber 126 and chamber 141 of the die shoe. In addition, a flexible hose 145 connects the manifold 136 with a passage 146 in movable sidewall 23, and the passage 146 serves to conduct water to the chamber 126 in the movable sidewall.

During the die-quench operation, cooling water flows abundantly from the

surfaces

76 and 77 of male die 73 and from the surfaces 24, 25 and 26 the female die 18 which are in contact with the channel member 19. The water then drains into the pit 3, and is recirculated up through the pump 138, back through the manifold 136, and through

flexible hoses

135, 143 and 145 to the individual die flow systems to provide a continuous supply of quenching water to each die unit 1.

In operation, a red hot channel member 19 is placed, web down, on the several knockout platens 121, which are disposed at the top level of the female dies 18. The platens 121 are then lowered into the base sections 20 of the female dies 18, leaving the channel member 19 resting on the base sections. The movable sidewalls 23 are then moved in laterally against the side of the hot channel member 19 by introducing fluid into the fixed cylinder 30 through line 57 to clamp the channel member in the female die and simultaneously hot straighten it. The tandem cylinder assembly is adapted to limit the lateral movement of the movable sidewall 23 in its initial clamping action to avoid crushing the hot channel member. Immediately upon hot straightening of the channel member, the male die 73 is moved down to engage the inside surfaces of the channel member 19. As the male die moves into the channel member, the resistance of the web portion causes the male die to expand later-ally so that its waffle-like surfaces 76 contact the inner surfaces of the flanges of the channel member.

After the male die 73 is positioned within the'channel member, hydraulic fluid is introduced into the movable cylinder 31 through line 58 while maintaining the pressure I in cylinder 30 to urge the movable sidewall 23 inwardly.

As soon as the channel member is firmly clamped at all surfaces, the quenching water is simultaneously pumped out through all the die-quench units 1 under pressure to provide an abundant and uniform flow of quenching water at all surfaces of the channel member 19. This rapid flow of coolant causes the channel member to shrink longitudinally, and, as described above, the male die 73 and the female die 18 are adapted to follow the shrinking channel member to its cold bar dimensions. In addition, the fluid pressure acting in cylinder 31 enables the movable sidewall to follow lateral shrinkage of the channel member.

After quenching, the male die 73 is raised and the movable sidewall 23 is retracted. Knockout platens 121 are then moved upwardly into engagement with the channel member to remove the channel member from the female die 18.

The amount of longitudinal motion of each die section of the longitudinal series increases progressively as distance of the section from a shrinkage reference point increases. In the present embodiment of the invention. the shrinkage reference point is the midpoint of the length of the channel member. The male dies 73 and female dies 18 which are immediately adjacent the midpoint of the channel member move only a small amount of linear distance during quenching, because they are nearest the reference point. The next adjacent male dies 73 and female dies 18 proceeding longitudinally in either direction from the midpoint of the channel member are required to move a larger distance to follow the progressively increasing shrinkage of the channel member. The amount of shrinkage for any given portion of the channel member 32 is calculated in advance, and the required longitudinal arc of movement is pre-set on each male die 73 and female die 18 by

gages

68 and 107. After the preset is made on each die section, they are resiliently held in their outward positions in relation to the midpoint of the hot channel member, which is then loaded into the die-quench machine. All die sections firmly engage the hot channel member, and as the quenching proceeds and the channel member shrinks, each die section follows the specific portion of the channel member longitudinally toward the midpoint, thereby avoiding non-uniform stresses in the quenched channel member. At the end of the quenching operation, the adjacent die sections are still spaced apart slightly, although the spaces between them are less than at the beginning of the quench cycle, due to the shrinktravel of each die section following the motion of the channel member 19. The spacing between the die sections is necessary to avoid interference between adjacent die sections which would cause unequal stresses on the channel member 19, as mentioned previously.

The die-quench method of this invention may be adapted to quench all solid materials which are heat treatable. The materials should be those which will change from a particular crystalline or molecular phase, or combinations thereof, to a uniform phase which has the improved tensile strength and hardness desired when rapidly quenched from an elevated temperature.

As pointed out above, the collapsing action of the diequench machine will follow the shrinking motion of the workpiece. The extent of following motion for the particular material being quenched is calculated in advance for that particular material, and is based on the relationship between the coeflicient of expansion of the particular material, the temperature difference of the material just before and just after quenching, and the distance of the respective die unit from the center of the machine.

It has been discovered that the method of this invention is particularly adapted to quenching a lean alloy steel which is referred to as an intermediate manganese steel. The chemical composition of this steel is approximately as follows:

C .22.30%. Mn l.0-1.35%.

P .04 maximum. S .05 maximum. Fe Balance.

Before heating and quenching, this steel has approximately the following physical properties:

Tensile strength 78,000 p.s.i. minimum. Yield point 45,000 p.s.i. minimum. Elongation in two inches 30% minimum.

After die-quenching, one sample of the quenched steel had approximately the following physical properties:

Tensile strength 170,000 p.s.i. minimum. Yield point 150,000 p.s.i. minimum. Elongation in two inches 10.0% minimum.

After subsequently tempering this quenched steel sample at a temperature of about 900 F., it tested approximately as follows:

Tensile strength 130,000 p.s.i. minimum. Yield point 110,000 p.s.i. minimum Elongation in two inches 18% minimum.

These latter physical properties are considered ideal for use as a truck trailer side rail.

To obtain the desired steel just described, the intermediate manganese steel workpiece is first heated to a temperature in the range from l4501750 F. This step is believed to cause the various crystalline phases contained in the steel to dissolve, and the red hot steel workpiece is then loaded into the die-quench machine, straightened and quenched, as previously described. Although water is preferred as a quenching media, other quench media can be used, such as a solution of NaOH, a salt brine solution, or a solution of polyvinyl alcohol. It is important that the straightening of the workpiece take place just before the quenching commences, and that rapid quenching commence before the workpiece has cooled to 1335 F. If quenching of this particular steel does not commence above this critical temperature, undesired crystalline phases such as pearlite and bainite will form in the steel and give undesired and non-uniform physical properties to the workpiece.

The rapid and uniform quench made possible by the apparatus of this invention produces a steel having about a martensite crystalline structure. As mentioned above, this quenched steel has physical properties which are greatly improved over the intermediate manganese steel prior to quenching. For the particular use, the quenched steel workpiece was subsequently heated for a period of time at about 900 F. to decrease the hardness and thereby increase the elasticity. The increased elasticity is particularly desirable in elongated truck trailer side rails.

In summary, this invention provides a novel diequench apparatus and method for hot straightening and quenching heat treatable materials to obtain quenched materials of greatly improved physical properties. This invention is particularly adapted to quenching long intermediate manganese steel channel members used for truck trailer side rails.

Various modes of carrying out the invention are contemplated as being within the scope of the following claim particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

A method of straightening and quenching an elongated channel member of intermediate manganese steel having a chemical composition of .22% to 30% carbon, 1.00- 1.35% manganese, not more than .04% phosphorus, not more than 05% sulphur and the balance iron, the steps comprising, heating the channel member to a temperature in the range of 1450 F. to 1750 F., while disposed in a series of longitudinally moveable, laterally expandable die members adapted to clamp said channel member, straightening said channel member by means of a clamping force applied by said die members while the channel member 1 l 1 2 is at a temperature above 1450 F., and thereafter uni- References Cited by the Examiner formly and simultaneously subjecting all the surfaces of UNITED STATES PATENTS said member to an abundant flow of quenching liquid under pressure while holding the channel member with 3,201,237 8/1965 Flowers 148-114 X said die members without restraint against lateral and 5 FOREIGN PATENTS longitudinal movement during quenching, thereby uniformly quenching the workpiece to a temperature not more than 900 F. through its stock thickness within thirty seconds to provide a substantially uniform marten- DAVID RECK Primary Examiner sitic crystalline microstructure therein. 10 C. N. LOVELL, Assistant Examiner.

120,225 7/1945 Australia.