US3410334A - Method of controlling molten metal height in a successive molds casting operation - Google Patents

Description

Nov. 12, 1968 w. G. DRESSEL 5 3 METHOD OF CONTROLLING MOLTEN METAL HEIGHT IN A SUCCESSIVE MOLDS CASTING OPERATION Original Filed April 14, 1965 5 Sheets-Sheet 1 I/VVENTOR.

WILL/AM a. DRESSEL WITNESS A3553 3,410,334 METAL HEIGHT IN A SUCCESSIVE MOLDS CASTING OPERATION Original Flleci April 14, 1965 Nov. 12, 1968 w G. DRESSEL METHOD 0? CC TROLLING MOLTIf-N 5 Sheets-Sheet 5 .z wenforx W/LL/AM G. DRESSEL CYZ: III] J Nov. 12, 1968 w. G, DRESSEL. 3,410,334

METHOD OF CONTROLLING MOLTEN METAL HEIGHT IN A SUCCESSIVE MOLDS CASTING OPERATION Original Filed April 14, 1965 5 Sheets-Sheet 4 INVENTOR. WILL/A M G. DRESS/5L WITNESS Q haz/flggg United States Patent "ice METHOD OF CONTROLLING MOLTEN METAL HEIGHT IN A SUCCESSIVE MOILDS CASTING OPERATION William G. Dressel, Elk Grove Village, Ill., assignor to Amsted Industries Incorporated, Chicago, 111., a corporation of New Jersey Original application Apr. 14, 1965, Ser. No. 448,017, new Patent No. 3,353,586, dated Nov. 21, 1967. Divided and this application Aug. 10, 1967, Ser. No. 659,655

1 Claim. (Cl. 164-433) ABSTRACT OF THE DISCLOSURE A gauging and sensing device is used to terminate the flow of molten metal into successive molds of varying heights. The gauging device is a vertically movable rod that contacts an external surface of the mold after the mold has been moved into pouring position. The external surface mentioned is fixed relative to the casting cavity of the mold in order that molds of varying heights may be accommodated. The sensing device moves down with the gauging device and into a riser opening of the mold, serving to terminate the pouring operation upon contact with the rising level of molten metal.

This is a division of application Ser. No. 448,017, filed Apr. 14, 1965, now Patent No. 3,353,586, issued Nov. 21, 1967. The present invention relates to mold riser height control for use in conjunction with casting operations.

To insure that there be suflicient metal in the riser holes to compensate for the shrinkage in the cavity, the operator often fills the mold and riser holes to a greater extent than is necessary to accommodate shrinkage. This results in the inefficient and expensive pouring of excess metal. It has been found difficult, if not impossible, to accurately control the pouring level by visual observation and manual control, and while automatic sensing and other control devices may be utilized, this has not been found to be practical in the filling of a succession of molds which are not uniform in dimension. Such non-uniformity in dimension may be caused by, for example, resurfacing or reconditioning mold parts after repeated casting operations.

An object of this invention is to provide a method for gauging and sensing the height of molten metal in such riser holes, in order to terminate and otherwise control the casting operation.

Other objects and advantages of the invention will appear from the following detailed description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a semi-diagrammatic view of a conveyor arrangement for transporting molds to a pouring station, and of the crane means for manipulating the molds;

FIGURE 2 is a semi-diagrammatic view taken at line 2-2 of FIGURE 1;

FIGURE 3 is a large scale view of the apparatus of the present invention mounted on a crane for manipulating the molds, this view being orientated similarly to FIG- URE 1;

FIGURE 4 is a view from the left of FIGURE 3;

FIGURE 5 is a diagrammatic view showing the conveyor means with a plurality of molds thereon, emphasizing the difference of sizes in successive molds,

FIGURE 6 is a view similar to FIGURE 3 showing a second embodiment of the invention;

FIGURE 7 is a diagram of the hydraulic arrangement utilized in the embodiment of FIGURE 6; and

FIGURE 8 is a diagram of the electrical arrangement utilized in the embodiment of FIGURE 6.

Referring now to the drawings, FIGURES 1 and 2 3,410,334 Patented Nov. 12, 1968 show diagrammatically a conveyor arrangement for conveying the molds to a pouring station, and from that station therebeyond. The molds indicated at 10 are shown resting on and being conveyed by a conveyor 11 of known kind. In the illustration shown, the molds are conveyed to the right, and as each mold reaches the position shown at 10a the conveyor 11 stops and a crane 12 lifts the molds successively into pouring position indicated at 101), and then out of that position and again onto the conveyor where they are conveyed away from the pouring station. The crane 12, of known kind, is moved along an overhead track 14 between the full-line and dotted-line positions. The crane includes an A frame 16 and a B frame 18 extending downwardly into proximity with the conveyor 11, and utilized for lifting the molds into and out of the pouring position. Each the A frame and the B frame is made up of two legs such as 16a and 16b in FIGURE 2, which straddle the molds. In the operation of the crane, and assuming first the full-line position of FIGURE 1, the A frame 16 grips the mold at the position 1012, while at the same time the B frame 18 grips the mold at the position 10a, and the crane is then moved along the overhead track to the dotted-line position where the mold 10b is deposited on the conveyor 12 and the mold is deposited at the pouring position for the filling operation.

The pouring station includes a pit 22 in which a ladle 24 is deposited. Compressed air is introduced into the ladle 24, which is at that time sealed, through a conduit 26 by known means. Upon consequent increase in pressure, the molten metal in the ladle is forced up through the pouring tube 28 into the mold 1%, which is placed in pouring engagement with the pouring tube, as shown more clearly in FIGURE 3. Although such pressure pouring type of casting is here disclosed, the invention is not limited thereto but is applicable to other types, such as gravity pouring.

As best shown in FIGURES 3 and 4, the mold 10 is designed for casting railway car wheels, and as such includes a cavity 30 shaped for that purpose, but it will be understood that the invention is not limited to such cast article. The mold 10 is a chill mold and includes graphite drag and cope sections, 32 and 34 respectively, which together define the casting cavity 30. The drag section 36 is held between a bottom steel member 40 and a top steel member 42 having a flange 44. The top graphite section 38 is held between a top steel member 46, and a bottom steel member 48 which includes a flange 50.

The casting cavity 30 is preferably formed in both mold sections, i.e. an upper portion 30a is formed in the underface 52 of the cope section 38, and another portion 30b is formed in the upperface 54 of the bottom or drag section 36. In the course of casting, it becomes necessary or advisable to recondition the graphite sections of the mold, due to deterioration by the molten metal. This is done by separating the mold and exposing the faces 52 and 54 of the sections thereof, and performing the reconditioning or resurfacing operations on those faces. This operation reduces the depth dimension of those sections which may vary between, for example, 21" in a new mold to about 14" or less after a number of reconditioning operations. After such reconditioning operations, the graphite sections are then incorporated again in the steel members and the latter clamped together. The bottom steel member 48 is applied to the bottom surface of the cope section 38 while the top steel member 42 of the drag is applied to the drag section 36, and the two sections of the mold fitted together again. These steel members 42 and 48 again assume the same position relative to the respective faces 54 and 52, and thereby are again in the same position relative to the cavity 30 regardless of the depth dimensions of the graphite sections 36 and 38. However, due to the reduction in depth dimensions of the graphite sections, the two steel members of each part of the mold will be closer together, that is, the steel members 40 and 42 will be closer together, and the same is true with respect to the steel sections 46 and 48. While the overall height or depth of the mold is reduced after each conditioning operation, the relation between the flanges 44 and 50, and the cavity, remains the same as noted above. This phenomenon will be referred to again herein below, with respect to the sensing operation.

The cope section 38 is provided with at least one, and preferably a plurality of, riser holes 56 communicating with and rising from the cavity. Each riser hole is provided with a liner 58, of sand or sand mix, having an undersurface 58a shaped according to the adjacent portion of the article to be cast. A relatively small aperture 60 is provided for allowing the molten metal to rise into the riser hole and recede into the cavity. The liner 58 and the method of placing it into position are known.

The A frame 16 is shown in FIGURES 3 and 4, having a foot 62 on each leg 16a and 161), the two feet gripping under the flange 64 of the bottom steel member 40 of the mold, in the operation of picking up the mold and setting it down.

The sensing apparatus in the first embodiment of the invention is indicated in its entirety at 66, and includes a carriage 68 mounted for vertical reciprocation on a channel support 80. The upper and lower ends of channel support 80 are secured to one of the legs, such as leg 16a of the A frame 16, by respective brackets 82 and 84. In order to facilitate the flow of gases from the casting cavity, the mold is tilted during the pouring operation and the sensing apparatus 66 is preferably disposed at a slight angle, on the order of 3 /2 from the vertical.

Additional brackets 86 and 88 are secured to the upper and lower ends of the channel support 80, and a guide rod 90 for guiding the movements of the carriage 68. The carriage 68 includes a headpiece 92 having an aperture for receiving the guide 90. The headpiece 92 is part of a frame indicated in its entiret at 94, which also includes a foot 96 having an aperture receiving the guide 90. Interconnecting the head 92 and foot 96 is a rod 98, and the carriage 68, head 92, rod 98 and foot 96 form a rigid and unitary assembly slideable vertically as guided by the rod 90. The sliding movements of this unitary assembly are provided by a power device 100 which may be pneumatically operated and which includes a cylinder 102 and a double acting piston 104 having connecting rods 106 and 108 respectively, connected to opposite sides thereof. The upper connecting rod 106 is connected to the head 92, while the lower connecting rod 108 is connected to the foot 96. Upon introduction of compressed air on one side or the other of the piston, the assembly 94 is moved up or down moving the carriage 68 with it.

The carriage 68 is secured to the head member 92 of the frame 94 and includes a horizontal arm 110 on which is mounted a sensing element 112 which, in the present instance, is in the form of a bob sufficiently light to float on molten steel. This bob, preferably of graphite or other suitable material, is secured to the lower end of a chain 114 for the most part encased in a protective tube 116 attached to the arm 110. The upper end of the chain is supported on one end of a lever arm 118 fulcrumed at 120, the other end having an element 122 operative for engaging and operating a switch 124. The bob 112 normally is sufficiently heavy to move the arm 118 in counterclockwise direction for holding the right hand end up to a first position, and upon the bob being raised by the molten metal, the arm swings in the opposite direction with consequent control of the switch 124. If desired, a counterweight 126 may be mounted on the right hand end of the arm for assuring movement thereof when the bob is raised. Also, the chain 114 may be provided with adjustment means 128 for adjusting the length thereof.

The foot 96 has an extension 130 which is provided for engaging one of the elements of the mold in the sensing operation, which is preferably the flange 44, which is one of those which always assumes the same position in the mold relative to the cavity, regardless of the size of the mold parts which are altered by resurfacing, as referred to above. Other flanges above the flange 44 may have notches therein for enabling passage of the extension 130 therepast.

After the mold is placed in pouring engagement with the ladle (FIGURES l and 3) as described above, compresed air is introduced into the cylinder 102 above the piston 104, in order to lower the carriage 68 and project the bob 112 into the riser hole 58. The carriage 68 and bob 112 are lowered until the foot extension 130 of the frame 94 engages the flange 44 on the drag section 32 of the mold, as shown in FIGURE 3. The flange 44 thus serves as a means for limiting movement of the carriage 68, and in this position the bob 112 is at the desired height in the riser hole 56 for performing the intended sensing operation, the length of the chain, of course, being predetermined to that end. As the molten metal flows into the cavity 30 and then into the riser hole, it engages the bob 112 at a level represented by the dotdash line 131 (FIGURE 3), the relatively rapid movement of the molten metal adding a component of force to the flotation of the bob to raise it. When the bob is thus raised, the arm 118 (FIGURE 4) rocks in clockwise direction, and the switch 124 is actuated as stated above. This switching operation is then utilized for the desired functions, a principal one of which is stopping the pouring operation. The number of functions controlled by this switching operation may be as desired, in accordance with the intended degree of automatic control, such as introducing compressed air under the piston, and opening the upper end of the cylinder and raising the carriage 68, as well as other functions such as moving the crane 12 for continuing the overall conveying movements of the molds and successive filling operations.

FIGURE 5 illustrates three similar molds, 10c, 10d and 10a, in which the graphite sections 36 and 38 have been reconditioned and varied in dimensions to different degrees. The graphite sections in these molds are in the three cases different from each other, but the flange 44 in each case is at the same height relative to the cavity therein so that upon the extension 130 engaging that flange, the sensing bob 112 is disposed at the same level in the riser hole relative to the cavity, regardless of the overall height or depth of the molds. The external steel members of the three molds are identical.

When a plurality of riser holes 56 are provided, the sensing step may be provided in any of the holes as desired, the carriage 68 being positioned relative thereto for that purpose. In the present instance, a riser hole at a lower portion of the mold is utilized, but the sensing step may be performed at the intended level by adjusting the height of the bob according to which of the riser holes is utilized.

While the foregoing embodiment of the invention utilizes a mechanical arrangement responsive to movement of the rising molten metal, the invention is not limited to such arrangement, as stated above and attention is now directed to FIGURES 6, 7, and 8 showing an arrangement in which an electrical circuit is utilized to control the level of molten metal. In FIGURE 6 the A frame 16 is shown on which is mounted a hydraulic power device including a cylinder 142 and a ram 144. The ram 144 includes a piston 146 operable in the cylinder and a rod 148 extending upwardly to a connection with tension springs 150, which are also connected with a fixed element of the apparatus. As best shown in FIGURE 7, extending in the opposite direction from the piston is a rod 152 forming a prod having a terminal element 154 which may be of stainless steel, and adapted to engage the molten metal in the riser cavity. The power device 140, including all parts thereof, is electrically insulated from the frame 16 and other conductive parts of the apparatus, for eifective inclusion in an electrical circuit described hereinbelow. Above the piston 146 is a chamber 156 having oil therein in a hydraulic circuit referred to hereinbelow.

Also mounted on the frame 16 is another hydraulic power device 158 (FIGURE 7) having a cylinder 160 and a ram 162 connected with a piston 164. The ram 162 extends downwardly out of the cylinder for engagement with an element of the mold for forming a sensing and limiting means of the general kind described above. Below the piston 164 is a chamber 166 having a quantity of oil therein, this chamber being connected through a hydraulic line 168 with the chamber 156 in the power device 140, the hydraulic line including a flexible element 170, if desired, for convenience in mounting the apparatus.

Below the piston 146 in the power device 140 is a chamber into which compressed air is introduced. Leading from this chamber 172 is a pneumatic line 174 having a flexible element 176 which, as controlled by a valve 178, communicates with another pneumatic line 180 which in turn communicates with the chamber 182 above the piston in the cylinder 160. Another pneumatic line 184 communicates with a suitable source of compressed air (not shown) and leads to the valve 178 and under control of that valve communicates selectively with the chamber 172 and 182, the compressed air being operative for actuating the pistons as described below.

As shown in FIGURES 7 and 8, the valve 178 is controlled by a solenoid 190 and is connected through a conductor 192 with the prod 152. Another conductor 194 leads from the mold through a source of potential 196 to another conductor 198 leading to the solenoid 190. The solenoid 190 is operative for controlling a set of instrumentalities indicated in its entirety at 200 which may include, as indicated, valves, switches, relays, etc., the valves including the valve 178 identified above.

In the use of the apparatus of FIGURES 6 to 8, with the A frame 16 in the proper position relative to the mold being filled, compressed air is introduced through the line 184, valve 178 and line 180 to the pneumatic chamber 182 of the cylinder 160. This forces the ram 162 downwardly until it engages the intended element such as the flange 44, as described above. This downward movement of the ram displaces the oil from the chamber 166 through the line 168 into the chamber 156 and correspondingly moves the piston 146 downwardly. The latter movement moves the prod 152 downwardly into the riser hole of the mold to the position as determined by the extent of movement of the ram 162, and reaches its lowermost position upon the ram engaging the flange 44. After the members reach this position, the pouring operation is performed until the moltenmetal reaches the level as indicated at 132 in FIGURE 8, when it engages the prod 152. This closes the circuit of FIGURE 8 and energizes the solenoid which in turn actuates the set of control instrumentalities 200. These instrumentalities control various operations including the pouring operation, for example, and actuate the valve 178 which reverses the flow of compressed air and raises the piston 146, which of course, raises the ram 162.

It will be understood that all of the components and elements involved in the electrical circuit of FIGURE 8 which include all portions of the power device 140, are electrically insulated from all other parts of the apparatus whereby the circuit of FIGURE 8 is energized by the prod 152.

While I have herein disclosed a preferred form of the invention, it will be understood that changes may be made therein within the scope of the appended claim. I

Having thus described the invention, what is claimed is:

1. The method of controlling the height of molten metal in a casting operation wherein successive molds having casting cavities of successively variable heights are filled, comprising the steps of providing a location remote from each successive casting cavity such that respective locations are similarly fixed relative to the height of respective casting cavities, moving a gauging element to said location for each successive mold and moving a sensing element into the mold to a predetermined extent relative to the extent of movement 'of said gauging element, and filling each successive mold with molten metal and terminating the filling operation as the molten metal contacts the sensing element.

References Cited UNITED STATES PATENTS 2,319,075 5/1943 McKinnis 141-498 2,891,292 6/1959 Sukava 164l56 J. SPENCER OVERHOLSER, Primary Examiner.

P. D. BALDWIN, Assistant Examiner.

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