US2641806A - Ingot stripper - Google Patents

Description

R. J. LECKRONE 2,641,806

June 16, 1953 INGOT STRIPPER s Sheets-Sheet 1 Filed Jan. 29, 1949 INVENTOR RoY J. LECKRONE a; ,1 mg.

June 16, 1953 R. J. LECKRONE INGOT STRIPPER 5 Sheets-Sheet 2 Filed Jan. 29 1949 INVENTOR RoY J. LECKRONE .N h m June 16, 1953 R. J. LECKRONE 2,641,806

INGOT STRIPPER Filed Jan. 29, 1949 5 Sheets-Sheet 5 11 6'. .ZL E3 INVENTOR R Y J.LECKRONE I Patented June 16 1953 2,641,806 INGOT STRIPPER Roy J. Leckrone, Mount Lebanon, Pa., assignor to Pittsburgh Engineering and Machine Company, Pittsburgh, Pa., a corporation of Pennsylvania 7 Application January 29, 1949, Serial N 0. 73,473

1 Claim.

* This invention .relates to the stripping of ingots from molds and more particularly to apparatus for stripping ingots from the molds in which they are cast, particularly in the case of large metal-ingots. e I

The apparatus required for stripping .large ingots from their molds is necessarily large .and powerful in view of the weight of the mold and the ingot and in view of the considerable force necessary to separate the mold from the ingot.

Two kinds of ingot strippers which are in common use are those which operate on the screw principle and are mounted on special overhead traveling cranes and those which operateon the ram principle and are mounted in a .fixed emplacement. A stationarily mounted stripper has the disadvantage that the mold with the ingot therein must .be brought to the stripper for strip- .ping and then the ingot and mold must be removed from the location of the stripper to the places where they are respectively needed. The screw type of stripper mounted on a special traveling scrane has the advantage of mobility but the cost of a special crane .for the stripper is .high and the special crane interferes with the movement of the other overhead crane or cranes in the same plant.

I provide a self-contained ingot stripping unit which may be suspended from the hook .of a traveling crane while the stripper is in .use'and may be removed from the crane andstoredelsewhere when the stripper is not in use. Aspecial crane is not required; any conventional or other overhead traveling crane of suflicient capacity may be used. Moreover, the craneis used for supporting the stripper-only at times when molds are to be stripped.

My stripper in addition to being portable is inexpensive and its maintenance cost .is low. It is of relatively light weight and any standard ten, fifteen or twenty ton crane can .be used to carry it. My stripper will strip the same sizes and types of ingots as a standard stripper of mucch greater weight and cost.

My stripper preferably employs a self-contained power unit which is remotely controlled fromthe crane cab. I preferably utilize a hydraulic ram which through the remote control apparatus may be moved relatively slowly and with relatively great force in stripping an ingot and may be returned to its initial position relatively quickly. This may be accomplished'by a duplex pump system which renders available selectively hydraulic fluid under relatively high "pressure moving at relatively low speed and hydraulic fluid under 'relativelylow pressure moving at relatively high speed.

My stripper preferably employs mold gripping means and ingot pushing means. sp'ective means may be connected so that the gripping and stripping functionsmay be accomplished in-Fa single operation. Means are prefer- I ably provided .in connection with the ingot pushing means for controlling movement of the ingot mold gripping means between operative and inoperative positions.

I provide for lifting the stripper -together with the mold and the ingot therein and pushing the ingot down out of the mold while the mold is suspended. The stripper may then carry the empty mold to any desired location and deposit it. Other details, objects and advantages of the invention will .become apparent as the following description of certain present preferred embodiments thereof and certain present preferred methodsof practicing the same proceeds.

In the accompanying drawings I have shown certain present preferred embodiments of themvention and have illustrated certain present preferred methods of practicing the same, in which:

Figure l is a View partly in elevation and partly central vertical cross section .of an ingot stripper with most of the hydraulic connections removed for clarity;

Figure v2 is a diagram showing the hydraulic connections of the ingot stripper;

Figure 3 is a side elevational view to reduced scale of the ingot strippershown in Figure 1;

Figure 4 is a f-ront-elevational view of the ingot stripper shown .in Figures 1 and 3;

Figure 5 is a fragmentary front elevational view showing :aportion of the stripper with the gripping tongs spread apart;

Figure :6 is a fragmentary cross-sectional view to greatly enlarged scale showing a di-fierent :form .of structure in which the gripping tongs are operated by theram through linkage;

Figure '7is a fragmentary side elevational view I of the structure shown in Figure 6; and

Figure .8 is a fragmentary :front elevational view of the structure shown in Figures 16 :and 7 showing the parts in one position in solid lines and in another position in chain lines.

Referring .now :more particularly to the drawrings and considering :first the form of structure shown Figures 1-5,, there provided a rigid frame .10 including a :body portion LI and an invented 1U -b.art2 bolted at each end to the body portion 1! I. Structural tmembers 13 are welded within :the top of the iii-bar l2 :and define the upper extremity of the 'U bar an :opening ll l extending therethrough .beneath the top thereof, the opening 14 constituting aneve adapted to re- :ceive the heck of a traveling crane so that the hook mayengage the top of :the U-rbar l2 inorder to support the stripper. When not in use the stripper is removed from the crane .hook and is supported by opposed-extensions l5 :(FigureB') -.of

the body portion 'M respectively .on opposite sides -of the body portion and having downwardly :facing surfaces 16 adapted :to rest on spaced stationary supports (not shown).

'iflhesstripp'er has a of dependent tongs ll?! pivotally mounted on the body portion I at Ila and having hooks I8 at their lower ends extending inwardly and upwardly for the purpose of engaging beneath the lugs on opposite sides of conventional ingot molds. The weight of each of the tongs I! is so distributed that when the tongs hang down freely their hooks I8 are suitably spaced for gripping an ingot mold. While the tongs I'I grip the mold a ram l9 now to be described extends between the tongs I! and pushes down on the ingot in the mold until the ingot is stripped from the mold.

The ram I9 comprises a head 2!] at its lower end, a double-acting piston 2| operable in a cylinder 39 presently to be described at its upper end and a piston rod 22 secured to the piston 2| and extending downwardly therefrom. The rod 22 extends through an opening in the bottom of the body portion I I and is slidably mounted in bearings 23 and 24 spaced one above the other and secured to the body portion II. Packing 25 fills the space between the bearings 23 and 24, the body portion I and the piston rod 22. The bearings 23 and 24 and the packing 25 are held against downward movement by a ring 25 extending around the piston rod 22 and bolted to the bottom of the body portion I I. The lower end of the piston rod 22 has a recess 27 receiving a neck 28 extending up from the ram head 29. A key 29 extends horizontally through the lower end of the piston rod 22 and through the neck 28 in order to attach the ram head 29 to the piston rod 22 securely but removably. Downward pressure of the piston rod 22 on the ram head 29 is transmitted principally from the lowermost end of the piston rod 22 to the upper surface of the ram head 20 surrounding the neck 28, and when this pressure is removed the key 29 prevents the neck 28 of the ram head 29 from sliding downwardly out of the recess 2'! of the piston rod 22. The lower end of the piston rod' 22 is reduced in circumference to provide a narrow overhanging shoulder 39 and is encircled by a ring 3| which has a lower edge resting on the top of the ram head 20 and an upper edge projecting outwardly from beneath the shoulder 39. Openings 32 extend through opposite sides of the ring 3! in order to permit the key 29 to be passed through the ring 3| to lock and unlock the piston rod 22 and the ram neck 28, and the key 29 is held in place by rotating the ring 3| relative'to the piston rod 22 and ram head 29.

A cam 33 actuates the tongs ll and is actuated by the ram I9. The cam 33 has a collar portion 34 encircling the piston rod 22 between the rings 25 and 3|. A bearing 35 secured to the collar portion 34 is in sliding engagement with the piston rod 22 and part of the collar portion 34 extends beneath the bearing 35 adjacent the piston rod 22 in order to engage the projecting upper edge of the ring 3| when the ram [9 is retracted upwardly. Cam fingers 35 project on either side of the collar portion 34 toward the tongs IT. The upper portions of the tongs I! have inwardly and downwardly facing sloping surfaces 31 extending above the cam fingers 36, and during the upstroke of the piston rod 22 the ring 3| engages the collar portion 34 of the cam and forces the cam fingers 36 upwardly against the sloping surfaces 31 in order to spread the tongs I! apart (Figure The sloping surfaces 3'! are flanked on both sides with walls 31a forming guideways for the fingers 35 to maintain them in proper cooperative relationship with the surfaces 31. Projections 38 extending inwardly from the tongs I'I beneath the cam fingers 36 engage those fingers and support the cam 33 while the tongs I! are in their freely dependent position (Figures 1 and 4). While the cam 33 rests on the projections 38 the piston rod 22 slides through the collar portion 34.

The piston 2| is slidable within a cylinder 39 in the body portion I which is lined by a cylindrical liner 49. The cylinder is closed at the top by a closure member 43 bolted to the body portion I I.

,A fluid conduit 4| extends through the body portion into the bottom of the cylinder 39 and a fluid conduit 42 extends into the 'upper end of the cylinder 39 through the member 43.

The hydraulic system serving the cylinder 39 through the conduits 9! and 42 is powered by a constant speed electric motor 44 mounted on a platform 45 which is secured to the body portion II and to the U-bar l2 of the stripper frame H). The motor 44 through a belt 46 drives a conventional duplex pump 42. The pump 41 and the other elements of the hydraulic system of the stripper are mounted on the frame ill of the stripper and are illustrated diagrammatically in Figure 2. The pump 41 comprises a positive drive radial piston pump 48 capable of delivering hydraulic fluid at a relatively slow rate and at a maximum pressure of about 4080 pounds per square inch and a positive drivegear-type pump 49 capable of delivering hydraulic fluid at a relatively fast rate and at a maximum pressure of about 30-0 pounds per square inch. The inlets of the pumps 48 and 49 are separately connected to a hydraulic fluid reservoir 50. The outlet of the pump 48 is connected to a conduit 5| and the outlet of the pump 49 is connected to a conduit 52. A 3000 pounds per square inch relief valve 53 is connected to the conduit 5| and exhausts into the tank 55. A conduit 54 connects the conduit 5| and a 300 pounds per square inch check and choke valve 55 controlling the operation of the pump 49. When the pressure in the conduit 5| and hence in the conduit 54 is below 300 pounds per square inch the valve 55 does not affect the operation of the pump 49, but when the pressure in the conduits 52 and 54 exceeds 300 pounds per square inch the valve 55 opens a by-pass (not shown) from one side of the pump 49 to the other so that the pump merely circulates hydraulic fluid within itself and does not feed hydraulic fluid into the conduit 52. The pump outlet conduits 5| and 52 are connected to a main supply conduit 56 and a check valve 51 is connected to the conduit 52 to prevent back pressure at the outlet of the pump 49 from exceeding 300 pounds per square inch when the pressure in the conduit 56 rises above 300 pounds per square inch.

A valve 58 controls the flow of hydraulic fluid between the duplex pump 41, the ram cylinder 39 and the reservoir 59. The valve 59 is a conventional electric pilot operated 4-Way valve manufactured by the Oilgear Company of Milwaukee, Wisconsin, and has an inlet port 59 connected to the main supply conduit 53, an outlet port 69 connected to a conduit 5| exhausting into the, reservoir 59, a port 52 connected to the conduit 42 extending into the upper part of the cylinder 39 and a port 63 connected to the conduit 4| extending into the lower end of the cylinder 35. A slidable spool valve within the valve 58 is movable to a neutral position in which the ports 59 and ;.69 are connected to return the fluid from the main supply line 53 to the reservoir and at the same time the ports 62 and 63 are connected so that the conduits 4| and 42 open into each other and establish a by-pass line .zfrom the upper and lower interior portions of the cylinder 39. In another position of the ,slidable spool valve the main :supply conduit 25.6 .is connected to the conduit while the "port :63. connected to :theiport 60 so that as fluid is connected with the conduit :41 and at the same time the 'lpOIt .62 is connected to the port -60 so that as :flui'd enters the lower portion of 1 the cylinder 13:9 through the conduit M .an equal T "amount :of :fluid will :be -exhaus.ted through the upper portion of the cylinder through the concluit 42 into :the conduit 6] exhausting into the i-reservoir 5,0. In order tosupply the power .-neces- 1 sary to move the :slidable spool valve :a :conduit 16A :is connected :to the main supply conduit -56 with .a branch '65 connected to one :end of the valve :58 and a branch 6.5 connected to the other end of the valve :58 :in .order to provide pressure within the conduit 64 when the duplex pump .41.is not working against .a ,load on the ram I9. An orifice 5.1 is mounted in the main supply conduit .56 .on the 'downstream side of the junction of conduits 5.6 and M. When the =slidable vspool valve is in its neutral position the duplex .pump 11.! circulates fluid through a the main :supply contact :55 and back to the reservoir 50 through the conduit til at ,a rate determined by the combined delivery rates of :the pumps 48 and '49, andthe orifice 5-! builds :up about 80 .pounds per square inch upstream back pressure in the .main .supply conduit 56. This pressure extends through the conduit .64 and the branches 6:5 and 1 .36 .to provide the force to move the .slidable spool valve within the valve 58. When the duplexpump 4.1 is working again-eta load on the ram [9 the back pres- :sure in the main supply conduit .55 will be higher than the back pressure provided by the orifice 6 1. 'This will increase :theavaila'ble force to move the spool valve in valve '58 but will not alter the action of valve 58. Within the valve .is suspended from the crane.

$.58 selectively to any one of the three operating conditions described above. 7

The stripper is operatedthroughelectricaltconttro'ls from the cab .of'the crane from which -the stripperis operated. The motor 44 is-controlled by :conventional'push button controls but is :usually running constantly while the stripper The control and power leads for the motor and the control leads ."for'the solenoidszfifl and-'69 are led to a common :plug :(inot shown) which may be extendedup from the :stripper to be connected to a complementary lplug adjacent the crane hook. The lines connected to the complementary j plug ex- "tend upwardly to a reel mounted on the crane above the stripper. The reel takes up and pays out the lines as the stripper is raised and lowered. The linesiare electrically connectedto the crane cab in the case of the control circuits and to a power source in the case of the power line.

It is desirabletobuild up-a'high pressure onit-he piston 21 during its :downstroke so that the ram l9 will be effective to stripan ingot'from the mold held between the tongs l1. However, during the upstroke of the piston 2 l, the cam 33 operates to spread apart the tongs I! and it would be:hazardous to allow enough pressure to build up during the piston upstroke to force the tongs 1'1 apart while theyare supporting a mold. A relief valve I3 is therefore connected to the conduit 4l and this valve is set to open aby-pass conduit T tdischarging into the reservoir when the pressure in the conduit ll exceeds about 75 pounds per square inch. 'This pressure is sufficientto draw the cam 33 up to spread apart the tongs 1.1 when they are not gripping a mold but is insufficient to spread apart the tongs I? when they are gripping and supporting a full Or empty mold.

The stripper is operated as follows:

When the stripper-isnot in use it may be rested upon any suitable support such as a .U-shaped support resting on the ground and-extending .upwardly on {both sides of the tongs H to engage the surfaces Id of the extensions {1 5 of the stripper (Figure '3') When the stripper-is needed thehook V of a traveling crane is hooked through the eye 58 a solenoid '68 operates .a .pilot valve (not shown) which releases the pressure in .thebranch 66 to move the slidable spool valve in one divalve (not shown) to move the slidable spool valve in the opposite direction and a spring (not shown) returns the slidable spool valve to neutral position when the solenoids 68 and 69 open both of the pilot valves to apply .theequal pressures in the branches B5 and 66 against opposite ends in the spool valve. of the solenoids closes one of the pilot valves the'fluid entering through the'opposite pilot valve moves the spool-valve to one of its extreme positions. When this occurs the fluid which had previously entered through the closed pilot valve is expelled through an exhaust port atthe :end of the valve 58. The pilot valve exhaust port at one end of the valve 58 is connected to the exhaust conduit 61 by a conduit 10 and the When one pilot valve exhaust port at the other end of -.con'trols are provided to .cause the solenoids 68 and .69 to act through their pilot valves to move the slidable spool valve Within ithe valve 5 [4 under the top of the U-bar I2, the electric.

power and oontrol lines are plugged in from the stripper to connections on the crane as above explained'and the crane is then operated .to lift the stripper and to moveit from place to place .as desired. In order to strip a mold, the stripper is suspended by the crane over a mold with the ram '19 raised and the tongs l1 spread apart as shown in Figure "5. The crane is then operated to "lower the stripper over the mold and the electrical controls of the stripper are then operated to cause the valve 58 to connect the main supply conduit 56 with the conduit "42 for a sufiicient period to allow the ram [9 to 'move downwardly "with thecam 33 until the-tongs I? grip the lugs of the mold-with the tong hooks It. The valve 58 is then returned'to its neutral position in order to neutralize the pressures on the opposite sides of the piston 21 and the crane is operated to lift the stripper with the moldsuspended between its tongs Ill. The valve 58 is again operated to connect the main supply line :56 with the conduit 42 and the ram l9 resumes its downward movement until the ram head 20 touches the top of the ingot in the mold. During this period the downward movement of the ram lil'has require rela- "tively little :force :and the ram has been moved relatively quickly by the combined action of the pumps 48 and 49. If the ingot is easily removed from the mold the ram l 9 continues to move downward quickly, but usually the ingot is stuck to the mold and considerable force is required to free it from the mold. The force required to strip such an ingot induces a considerable back pressure in the main supply conduit 56 and the valves 55 and 51 thereupon operate to isolate the low pressure pump 59 from the rest of the hydraulic sytsem. This reduces the rate of flow through the main supply line 56 but the pump 48 has the power necessary to force the ram I9 against the ingot with sufiicient force to strip the ingot from the mold. The crane is operated to suspend the mold not far above a suitable support during the stripping operation so that the ingot will not fall very far after it is disengaged from the mold. After the ingot has been stripped the crane is operated to lift the stripper with the mold still suspended between the tongs ll until the mold is entirely free of the ingot and then the crane is operated to carry the stripper and mold to the place where the mold is to be deposited. The stripper and mold are then lowered until the mold is deposited on a support, whereupon the valve 58 is actuated by the electrical controls of the stripper to connect the main supply conduit 56 with the conduit 4| in order to cause the ram I9 to move upwardly to spread the tongs I1 apart and thus to release the stripper from the mold. The stripper may then be moved by the crane to another filled mold for another stripping operation or it may be returned to its fixed support and disconnected from the crane in order to release the crane for other operations.

In Figures 6-8 there is shown a structure in which the cam 33 is replaced by a ring or block 33a and the surfaces 31 and projections 33 on the tongs are done away with in favor of arms 34d extending outwardly from the tongs H. The block 33a comprises a split collar 35a secured together by bolts 36a and having a bearing 38a lining the upper part of its inner surface and in vertical sliding engagement with the piston rod 22. Part of the collar 350. extends under the bearing 360: and closely embraces the piston rod 22 in order to engage the projecting upper edge of the ring 31 when the ram is retracted upwardly. Arms 39a extend from opposite sides of the collar 35a and each arm 39a is disposed above an arm 34o extending from each of the pair of tongs H. The outer ends of the arms 39a are connected to the outer ends of the arms 34a by links 40a which are pivotally fastened to the arms 34a by pins did and are pivotally fastened to the arms 39a by pins 42a. The openings in the arms 39a receiving the pins 42a arevertically slotted to allow for vertical movement of the pins 42a as a result of changes of the angularity of links 40a as the block 3341 slides up and down on the piston 22.

The operation of the structure of Figures 6-8 will now be described. When the ram 19 is retracted upwardly the ring 3| engages the lower portion of the collar 35a and the block 33a is thereby raised and the arms 39a through the links 49a pull up the arms 34a of the tongs ll and thereby cause the tongs to pivot outwardly on their pins 1117. As the ram moves downwardly the block 33a is lowered and the tongs I! are thereby allowed to resume their normal dependent position. The block 33a comes to rest when the tongs have resumed theirnormal dependent position; thereafter the ram 19 continues its downward movement with the piston rod 22 sliding against the block 33a. During the return upward movement of the ram the ring 3| again engages beneath and raises the block 33a and the tongs are again spread apart.

While I have shown and described certain present preferred embodiments of the invention and have illustrated certain present preferred methods of practicing the same it is to be distinctly understood that the invention is not 1imited thereto but may be otherwise variously embodied and practiced within the scope of the following claim.

I claim:

An ingot stripper comprising a frame, a double-acting cylinder vertically mounted in the frame, means to supply fluid under pressure alternately to opposite ends of the cylinder, a piston in the cylinder, a piston rod secured to the piston and extending downwardly therefrom out of the cylinder, a cap secured to the lower end of the piston rod to engage an ingot, a pair of mold-gripping members pivotally mounted on and dependent from the frame to support a mold in fixed relation to the frame, said members being disposed on opposite sides of the piston rod and each having a slot facing the portion of the piston rod projecting from the cylinder, a ring slidable along the piston rod adjacent the lower end'of the cylinder, and ears extending from said ring into said slots, said slots having sides along which the ears are vertically slidable and having upper base surfaces Which face downwardly and slant upwardly toward the piston rod for camming the mold-engaging members outwardly as the ears move vertically upwardly against said upper base surfaces of the slots, and said slots havin lower base surfaces which face upwardly and support said ears after the mold-engaging members have swung toward each other into mold'engaging position, said cap being engageable with said ring to lift it and thereby carry the ears against the upper base portions of the slots to cam the mold-engaging members out wardly during a final portion of the retracting Y movement of the piston rod in the cylinder, said ring and the bottom of the cylinder having bearing surfaces which alternately slide along common portions of the outer surfaces of the piston rod during its cycle of downward and retracting movement.

ROY J. LECKRONE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 713,029 Wellman et a1 Nov. 4, 1902 781,708 Baltzell Feb. 7, 1905 792,630 Taylor June 20, 1905 800,712 Blount Oct. 3, 1905 801,136 Cheever Oct. 3, 1905 1,059,668 Gathmann Apr. 22, 1913 1,352,026 Price Sept. '7, 1920 1,570,474 Geer Jan. 19, 1926 1,774,082 Camerota Aug. 26, 1930 2,278,116 Nielsen Mar. 31, 1942 2,365,282 Lester et a1. Dec. 19, 1944 2,439,795 Urmetz Apr. 13, 1948 FOREIGN PATENTS Number Country A Date 7 9,312 Great Britain Sept. 27, 1906 564,208 Great Britain Sept. 18, 1944 611,884 Great Britain Nov. 4, 1948 422,823 France Mar. 31, 1911 633,211 Germany July 22, 1936

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