US3052935A

US3052935A - Ingot stripper

Info

Publication number: US3052935A
Application number: US826664A
Authority: US
Inventors: Edward C Peterson; Walter C Updegrave
Original assignee: Birdsboro Corp
Current assignee: Birdsboro Corp
Priority date: 1959-07-13
Filing date: 1959-07-13
Publication date: 1962-09-11
Anticipated expiration: 1979-09-11

Description

4 Sheets-Sheet 1 l lll! lll INGOT STRIPPER E. C. PETERSON ETAL.

Sept 11, 1962 E. c. PETERSON ETAL 3,052,935

INGOT STRIPPER 4 Sheets-Sheet 2 Filed July 13, 1959 0 4 ww s W m ma N NF R .C EU O wa n Mira; EJK/Zier n.,

INGOT STRIPPER 4 Sheets-Sheet 5 Filed July 13, 1959 Sept. 11, 1962 E. c. PETERSON ETAL 3,052,935

INGOT STRIPPER Filed July 13, 1959 4 Sheets-Sheet 4 /zf l 25 27 /20 ni? L .I J

United States Patent 3,052,935 INGOT STRIPPER Edward C. Peterson, Douglassville, and Walter C. Updegrave, Birdsboro, Pa., assgnors to Birdsboro Corporation, a corporation of Pennsylvania Filed July 13, 1959, Ser. No. 826,664 9 Claims. (Cl. 22-95) The present invention relates to strippers for removing big-end-up ingots from ingot molds.

A purpose of the invention is to grip the top of an ingot mold in a big-end-up stripper while pushing upwardly to dislodge the ingot.

A further purpose is to lock the ingot mold to the stripper by applying force to the top of the ingot mold.

A further purpose is to reduce or eliminate the dithculty through breakage of lu-gs on ingot molds.

A further purpose is to recover a llarge proportion of ingots which stick in the ingot mold.

A further purpose is to prevent the creation of bending moments on the clamping arms of the ingot stripper.

A `further purpose is to `bias the clamping arms so that they tend to swing outwardly away from the ingot.

A further purpose is to center the ingot mold on the stripper platform properly before stripping.

A further purpose is to distribute the locking force which holds the ingot mold to the stripper over a greater area so as to prevent a skew eect on the ingot.

A further purpose is to equalize the advance of centering heads in centering the ingot.

Further purposes appear in the specication and in the claims.

In the drawings we have chosen to illustrate a few only of the numerous embodiments in which the invention may appear, selecting the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

FIGURE l is a side elevation of an ingot stripper of the invention, partially sectioned on the line 1 1 of FIGURE 2.

FIGURE 2 is a lfront elevation of the device of the invention, partly sectioned on the line 2-2 of FIGURE 3.

FIGURE 3 is a top plan view of the ingot stripper of FIGURES l and 2 with the platform and one of the centering heads broken away to show the equalizing mechanrsm.

FIGURE 4 is a diagram of the hydraulic `system used in the invention.

Describing in illustration but not in limitation and referring to the drawings:

In prior art ingot strippers which operate on big-endup ingots, the ingot mold has been held by arms which grasp lugs or ears on the mold provided for holding purposes. When the ingots stick, it is not uncommon to break of one or more of these ears. When this happens it is extremely ditiicult to recover the ingot, and usually the mold is unusable for further work.

The ears on the ingot mold usually project perpendicularly to the walls of the ingot mold, and the force applied to hold the ingot mold creates a moment which causes stress concentration at the junction of the ear with the wall of the mold, and this frequently results in fracture at that point.

Furthermore many of the prior art devices have not ibeen eiective when the ears on the ingot mold have deviated yfrom normal as to size or position.

By the present invention the ears on the ingot mold are not used in holding the mold during stripping. Instead the top of the ingot mold is itself gripped, so that the likelihood of breaking any part of the ingot mold is eliminated.

In accordance with the invention, centering heads 3,@52,935 Patented Sept. 11, 1962 properly position the ingot on the platform of the machine and then clamping arms swing in and grip the top of the ingot mold, after which pushing vforce is applied to the ingot to dislodge it from the ingot mold. In respect to the force used to dislodge the ingot, the device of the present invention resembles Peterson et al. U.S. Patent No. 2,820,264, -granted January 2l, 1958, for Stripper.

Considering now the drawings in detail, an ingot mold of the big-end-up type contains an ingot 21. The ingot mold has lugs 22 near the top which are suitably engaged by a crane 23 in placing the ingot on the platform 24 of the stripper. There are also suitably lugs 22 near the bottom which have formerly been used to grip the ingot mold. As well known the ingot mold is open at the top and it has a suitable opening in the middle of the bottom and the cross Vsection of the mold is larger at the top than at the bottom.

0n all four `sides of the ingot mold are centering heads. The centering heads 25 at the long side of the ingot are slidea'ble horizontally toward and away from the ingot on guides 26 on the platform, and are manipulated toward and away :from the ingot by double acting

hydraulic cylinders

27 and 27 having piston and rod combinations 28.

The opposing surfaces of the centering heads 25 are chamfered at 30 to guide the ingot mold into-the cen- .tral position and have recesses 31 to avoid interference with the ears 22. In order to equalize the forward motion of the centering heads 25, each centering head has pivotally connected thereto at 32 lon the bottom an equalizing link 33, the opposite end of which is pivotally connected at 34 with a rocker 35 which is pivoted freely on a tubular shaft 36 surrounding the pintle 37 to be described.

On the short dimension of the ingot there are provided centering heads 38 which move toward and away from the ingot on slides 40 on the platform under the action of dou-ble acting

hydraulic cylinders

41 and 41 having piston and piston rod combination-s 42. As shown:

in FIGURE 3 the centering heads 3S are equalized by links 43 pivotally connected to the heads at 44 and pivotally connected at 45 to rockers 46 which swing freely on the tubular shaft 36. The forward surfaces of theV centering heads 38 are `similarly chamfered at 47 to guide the ingot mold into central position.

In order to anchor the ingot mold to the platform, a pair of clamping arms 48 are provided opposite the long sides -of the ingot mold. The arms both swing and translate with reference to the ingot mold. Each clamping arm 48 has an upper crosshead 50 which connects at its ends to tension rods 51, which at the lower end connect with lower crossheads 52. v

`Each upper crosshead has at its lower surface c011- verging or -wedge sun-faces 53 which meet iat an apex 54 at the bottom which extends across the crosshead and in the plane of the longitudinal axes of the Itension rods for the particular arm. The upper crosshead is of lchannel cross section provided `with ianges `5S protruding from Ithe side remote from the ingot mold which overbalance or bias the upper crosshead and the 'clamping arms outwardly away from the ingot mold.

When the arms 48 move in, the apex 54 seats on the top of the ingot mold `to one side of the ingot mold, and the apex 54 lies in ythe axis of shear of the top crosshead, so that there will not =be a tendency to bend the tension rods 51. Thus the line of load application which passes through the apex 54 passes through the shear center of ythe channel section of the upper crosshead.

Each lower crosshead 52 has lugs 53' which pivotally connect through pin '54 with an equalizer beam 55' vwhich extends across and pivotally connects through a 3 f pin 56 ywith the lower end of lower ram `57 of a hydraulic system to be described. t

=In order to give very Ifree swinging of the clamping arms 48, and permit the use of a very light construction -or the pins I54', pins 54 iit very loosely in the holes through theequalizing beam 55', and cylindrical projections 552 'are provided at opposite ends of the equalizing beam ywhich engage in and receive concave sockets 52 on the lower crossheads `52 as shown in' FIGURE 1, when load is applied to the clamping arms.

A main hydraulic cylinder 60 `for the rams extends vertically, -being mounted in the frame at 61.

The main hydraulic cylinder is open at the top and also the bottom. At the bottom the Imain hydraulic cylinder receives lower ram `57 which is provided with piston packing at 62 and cylinder packing at 62. Hydraulic fluid is introduced for the main effort of the lower ram 57 in the space 63 above the lower ram and below the upper ram 64 which operates in the same cylinder. For pull back purposes there is a clearance at 65 between the lower ram 57 and the cylinder to which hydraulic fluid is admitted to act on the lower edge of `the piston.

The upper ram 64 has piston packing at 66 and 'cylinder packing at 67 and is actuated by hydraulic iluid in the same space at 63 between the two rams. The upper ram 64 has at its upper end a socket mounting 68 which receives a ball on the pintle 3-7. The pintle acts upwardly through an opening in the center of the platform and the stripper opening in the bottom of the ingot mold against the bottom of the ingot.

There is a clearance space 70 between the upper ram 64 `and the cylinder delined by the piston packing and the cylinder packing which is used to receive hydraulic dluid for pull back purposes. The pintle socket bearing and pintle are held together by a head 71 suitably bolted to the upper ram. The ball and socket joint on Ithe pintle corrects for misalignment of the stripper opening in the ingot mold 'The pintle head carries a stop 71 which in the fully extended position of the -upper cylinder engages against a stop receiver 36 supported on the bottom of the platform.

In order to cushion shocks between the rams, there is desirably a recess 72 in the upper ram which cooperates with a projection 73 on the lower ram to provide a dashpot action.

Mounted on the centering heads 25 at each side there isa cam 74 which has an upper and suitably horizontal cam surface 75 and an inner and generally vertical cam surfacej. These cam surfaces are engaged by a follower roller 77 pivotally mounted on a bracket 78 which extends outwardly from each tension rod '51.

f [n the device of the invention, mechanical equalization of the motion of the centering heads is shown in FIG- URE 3.

iWe prefer `also to use hydraulic equalization of this motion as shown in FIGURE 4, although permissibly the hydraulic equalization may be used as an alternative to the mechanical equalization.

IIn the hydraulic system, suitable electric motors 80 drive low pressure high volume pumps 81 and 83 and also relatively higher pressure pumps 82 and 84. The low pressure pumps 81. and 83 connect through check valves 85 and 86 and suitable piping to one side 88 of main -four-Way hydraulic valve l87. Likewise the high pressure pumps 82 and 84 connect through

check valves

90 and 91 and valves 93 in open position with the side 88 of valve 87. Main valve 87 in one position connects 'through suitable piping 94 with a space 63 between the pistons of the upper and lower rams. When desired the space between the pistons can be discharged by suitable piping through dumping valve 95. Main valve 87 in another position connects from the source of pressure through piping 95 to the

pullback spaces

65 and 70 of the respective rams. Y Y

4 Main valve 87 has hydraulic pilot cylinders 96 and 97 at its opposite ends which are operated through suitable piping .from four-way mechanical valve 98 which receives pilot fluid pressure through pipe 100 from pump 82.

Suitable two-way pressure relief by-pass valves for

pumps

81 and 83 are provided at 101 and 102. Low pressure pumps 81 and 83 are unloaded through

valves

101 and 102 when the pressure in line 88 exceeds the pressure for

lwhich valves

101 and 102 are set. Check valves and 86 prevent uid flow from line `88 through

valves

101 and 102.

Pumps

81 and 83 supply a large part of the oil volume before any stripping resistance is met. 84 are designed to deliver hydraulic liquid at a pressure somewhat higher than

pumps

81 and 83. period when the `stripper is inactive, al1 vfour pumps discharge lto drain `and the port to which line is connected is blocked, trapping the hydraulic liquid in

pullback spaces

65 and 70, and thus holding the rams in position.

Pump 82 also discharges through check valve 103 and pump S4 also discharges through check valve 104, and these streams connect and flow through piping 10'5 and normally

open valves

106 and 107 to accumulator chambers 108 and v110. Release of the accumulator pressure is provided through valves 111 and 112.

A pressure switch 113 is connected to the accumulator piping and it electrically lcontrols the operation of pilot operated solenoid valves 92 `and 93 so that in the event that pumps 82 and 84 are only discharging to tank through valve 87 and the pressure in the circuit beyond

check valves

103 and 104 containing accumulator chambers 108 and 110 falls below a predetermined value,

valves

92 and 93 will close, blocking discharge into line 88 and forcing the hydraulic liquid output to ilow through

check valves

103 and 104, thus restoring hydraulic liquid and pressure Ito the centering head circuit.

A suitable port 99 is provided inthe main cylinder wall from the space 63 which is uncovered when the stripping ram is near its upper limit of stroke as indicated in FIG- URE 4 and the port 99 communicates with check valve 99 from pipe 95. The port 99 is uncovered at approximately the position at which the pintle ram engages the stop on the platform and this relieves undue upward reaction on the platform as a safety measure, allowing the hydraulic liquid to discharge into the pipe comunicating with the pullback space 70.

Flow from pumps 82 and 84 passes the accumulator chambers and extends through piping 114 and flow control valves 115 to four-way lever operated valves 116 and 117 respectively.

The centering

head cylinders

27 and 27 are so constructed that the hydraulic liquid displaced from the rod end of one of these cylinders is equal to the hydraulic liquid necessary to be supplied to the head end of the opposing cylinder to make it go forward an equal stroke. Stated in a diiferent way, the rod end of one of these cylinders has an area equal to the head end of the other cylinder of the pair. The same area relationships exist also for the

cylinders

41 and 41. Y

When advancing the centering heads by cylinders 27 and 27', hydraulic liquid is admitted through pipe 118 to the forward moving side of cylinder 27'. From the opposite side 121 of cylinder 27', hydraulic liquid passes through pipe 122 to the forward moving side 123 of the opposite cylinder 27, thus advancing the opposite piston equally because the area relations are the same. From the opposite side 124 of the other cylinder 27 hydraulic liquid passes through pipe 125 to exhaust through lever operated valve 116.

In order to retract the centering heads 25, the valve 116 is thrown to admit hydraulic liquid under pressure through pipe 125 into side 124 of hydraulic cylinder 27. From the opposite side 123 hydraulic liquid ows through pipe 122 to the pullback side 121 of hydraulic cylinder 27'.y

Pumps 83 and During theV Hydraulic liquid from the oposite side of this cylinder 27 is discharged through pipe 118 and valve 116 to exhaust.

Valve 117 in one position admits hydraulic liquid under pressure through pipe 126 to forward moving side 127 of one cylinder 41. From the other side 12S of this one cylinder 41 hydraulic liquid iiows through pipe 130 to the forward moving side 131 of other hydraulic cylinder 41 of the pair. From the other side 132 of the hydraulic cylinder 41', hydraulic liquid passes through pipe 133 to valve 117 and exhaust.

On the pullback stroke there is a reversal, hydraulic liquid flowing through pipe 133 to cylinder side 132 of hydraulic cylinder 41', and then from the opposite cylinder side 131 to retracting cylinder side 128 of cylinder 41, while from the opposite cylinder side 127 hydraulic liquid flows through pipe 126 and valve 117 to exhaust.

Two-way valves 134 connect to the cylinder sides 121 and 123 of

cylinders

27 and 27 connect to the cylinder sides 139 and 131 of

cylinders

41 and 41 through check valves 135, and the two-way valves 134 are opened by tripping projections at 134' on the centering head cylinder rods when the rods are inretracted position. This arrangement introduces hydraulic liquid at pilot pressure to the lines interconnecting the opposite cylinders when they are fully retracted, thus making up for any leakage and reestablishing synchronisrn of the pistons.

In operation, an overhead crane 23 places an ingot mold containing an ingot on the stripper platform 24 as nearly central as possible, and the lower end of the ingot mold is guided down by the chamfered surfaces on the centering heads. The centering heads 38 are advanced, the motion of the heads being equalized by the mechanism of FIG- URE 3, or the mechanism of FIGURE 4, or both, so that the ingot mold is placed in the middle of the platform with respect to its wider dimension. This is accomplished by throwing valve 117 into the position to advance the centering heads.

When the ingot mold is properly centered the valve 117 is suitably moved to neutral position, releasing the hydraulic pressure and leaving the centering heads advanced but not pressing against the ingot mold. The operator next throws valve 116 into a position to advance the centering heads 28, thus centering the ingot mold on the platform with respect to its narrower dimension. Then valve 116 is placed in neutral position releasing the hydraulic pressure on the centering heads. The centering heads 25 move forward in unison because of the equalizing mechanism previously described. Because the ingot mold was first centered in the direction of its longer dimension, the ears 22 lit in the recesses 31 when the centering heads 25 advance.

As the centering heads 25 have moved forward, the arms 48 retain their same position initially and the follower rollers 77 simply roll over the top surface of the cam 74. if ,however, the ingot mold is unusually narrow, abutment 137 at the top of each cam on the side remote from the ingot mold engages the follower rollers and tends to make the arms begin to swing in toward the center of the ingot mold.

The operator then manipulates valve 98 to a position in which valve 87 introduces hydraulic liquid into the space 63 between the two main rams. This causes the main piston area of the lower ram and also of the upper ram to be conected to the main hydraulic pressure, but due to the downward acting weight of the bottom ram and the weight on the botom ram, it begins to move downward first before the top ram begins to move. As the bottom ram moves downward the follower rollers reaction on the top cam surfaces creates a moment and the clamping arms 48 are rotated about their pivot points on the equalizing beam to cause them to move inward toward the mold. The follower rollers 77 move along the top cam surfaces until they roll od the inner ends and then they contact the vertical cam surfaces while the lower ram and the clamping arms tend to move downward. Finally the upper crossheads come to rest on the top of the ingot mold at each side and the lower ram can descend no further,

As heavy pull is exerted on the clamping arms, the reaction overcomes the downward force due to the weight, and the clamping arms rise and the lower crossheads 52 bring their seats 52 into engagement with the ball portions 55 on the equalizing arms, taking the load olf the pins 54.

Pressure now builds up in the main cylinder 69 and overbalances the weight of the top ram, forcing the pintle up through the stripper opening in the bottom of the ingot mold against the ingot and eventually stripping the ingot by forcing it upwardly in the tapered cavity of the ingot mold.

After stripping is complete, the operator reverses his control valve 9S and bleeds hydraulic uid froml the space 63 between the rams as first the top ram descends until it cornes against its stop at the top of the cylinder and then the bottom ram is raised. During this action the off-center weight of the top crossheads cause an outward turning moment on the clamping arms which makes the follower rollers 37 follow the cam surfaces and retrace their path back to the starting point. Finally the centering heads are retracted and the ingot and ingot mold are lifted away by the crane.

In view of our invention and disclosure, variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the beneiits of our invention without copying the structure shown, and we, therefore, claim all such insofar as they fall within the reasonable spirit and scope of our claims.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

l. In an ingot stripper, a support for an ingot mold containing an ingot, an upper cross head above the ingot mold on either side, clamping arms extending downward from the upper cross heads on either side of the ingot mold, lower cross heads at the lower ends of the clamping arms, hydraulic cylinder and piston means including a downwardly directed piston, pivot means interconnecting the lower cross heads with the downwardly directed piston, permitting the lower cross heads, clamping arms and upper cross heads to swing around the ingot, synchronized means for urging the clamping arms toward the ingot mold to a position where said arms will descend to grip the upper surface of the ingot mold, said synchronized means for urging the clamping arms toward the ingot mold including centering heads positioned on opposite sides ofthe ingot mold and sliadable toward and away from the ingot mold in the direction in which the clamping arms move toward and away from vthe ingot mold, means for pushing the centering heads toward the ingot mold, means for equalizing the forward `motion of the centering heads, and means connecting the centering heads with the clamping arms comprising cam means on each centering head and follower means on each clamping arm riding the cam means, and said stripper further including means acting upwardly beneath the ingot for dislodging the ingot from the ingot mold.

2. In an ingot stripper, a support for an ingot mold containing an ingot, an upper cross head above the ingot mold on either side, clamping arms extending downward from the upper cross heads on either side of the ingot mold, lower cross heads at lthe lower ends of the clamping arms, hydraulic cylinder and piston means including a downwardly directed piston, pivot means connecting the lower cross heads with the downwardly directed piston, permitting the lower cross heads, clamping arms and upper cross heads to swing around the ingot, centering heads in opposed pairs on all four sides of the ingot mold slidable .toward and away from the ingot mold, two of said centering heads moving in the direction in which the clamping arms move toward and away from the ingot mold, means for advancing the centering heads, and means for equalizing the advance of the centering heads of each pair, synchronized means for urging the clamping arms toward the ingot mold toa position where said arms will descend to grip the upper surface of the ingot mold including means for interconnecting said two centering heads which move -in the direction of motion of the clamping arms -with the clamping arms, and means acting upwardly beneath the ingot for dislodging the ingot from the ingot mold.

3. In an ingot stripper, a support for an ingot mold containing an ingot, an upper cross head above the ingot mold on either side, clamping arms extending downward from the upper cross heads on either side of the ingot mold, lower cross heads at the lower ends of the clamping arms, hydraulic cylinder and piston means including a downwardly directed piston, pivot means connecting the lower cross heads with lthe downwardly directed piston, permitting the lower cross heads, clamping arms and upper cross head to swing around the ingot, synchronized means for urging the clamping arms toward the ingot mold to a position where said arms will descend to grip the upper surface of the ingot mold, comprising opposed centering heads sliding horizontally on the opposite sides of the ingot mold in the direction of motion of the clamping arms, means for advancing and retracting the centering heads in unison, means for equalizing the advance of the centering heads, cam means movable with the centering heads and followers on the clamping arms following said cam means, and said stripper further including means acting upwardly beneath the ingot for dislodging the ingot from the ingot mold.

4. An ingot stripper of claim 3, in which said cam means includes a generally horizontal stretch and a generally vertical stretch;

5. An ingot stripper of claim 4, in which said cam means comprises abutments moving the followers inward when the centering heads travel beyond a predetermined distance.

6. In an ingot stripper, a support for an ingot mold containing an ingot, centering heads positioned on opposite sides of the ingot mold and slidable toward and away from the ingot mold, means for pushing the centering heads toward the ingot mold, means -for equalizing the forward motion of the centering heads, clamping arms extending on either side of the ingot mold, means interconnecting the clamping arms to the centering heads for moving the upper ends of the clamping arms toward the ingot mold,means for pivoting the lower ends of the `clamping arms, means for pulling downward on rthe pivots of the clamping arms, and means acting upwardly beneath the ingot for dislodging the ingot from the ingot mold.

7. An ingot stripper of claim 6, in which the means interconnecting the clamping arms to the centering heads comprises horizontal cam means on the centering heads, vertical cam means on the centering heads and follower means on the clamping arms riding said cam means.

8. In an ingot stripper, a support for an ingot mold containing an ingot, an upper cross head above the ingot mold on either side, clamping ar-ms extending downwardly from the upper cross heads on either side of the ingot mold, lower cross heads at the lower ends of the clamping arms, hydraulic cylinder and piston means including a downwardly directed piston, pivot means connecting the lower cross he-ads with the downwardly directed piston, permitting the lower cross heads, clamping Aarms and upper cross heads to swing around the ingot, centering means acting on four sides of the ingot mold for locating the ingot centrally, means acting lfrom the centering means on the clamping arms for urging the clamping arms toward the ingot mold to a position where the arms will descend to grip the upper surface of the ingot mold and means acting upwardly beneath the ingot for dislodging the ingot from the mold. Y

9. An ingot stripper of claim 8, in which the centering means includes centering heads positioned on Opposite sides of the ingot mold slidable toward and away from the ingot mold in the direction yin which the clamping arms move toward and away from the ingot mold, means for pushing the centering heads toward the lingot mold and means for equalizing the forward motion of the centering heads.

References Cited in the file of this patent UNITED STATES PATENTS 1,323,255 DeWhurst Dec. 2, 1919 2,171,141 Dinzl Aug. 29, 1939 2,362,696 Hively Nov. 14, 1944 2,820,264 Peterson et al. Jan. 21, 1958