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1-, July 26, @380 B. F. DAVIDSON ET AL 2,125,057 MEANS F'TR PREVENTING THE ‘ADHERENCE OF MOLTEN METAL TO ANOBJECT Filed May 29, 1935 ' [N VEN TORS f DAVIDSON and GARE/V66 Filo/1m; A TTORNEY 2,125,067 Patented July 26, 1938 UNITED STATES ' PATENT ‘OFFICE 2,125,067 MEANS FOR PREVENTING THE ADHERENCE 0F‘ MOLTEN METAL TO AN OBJECT‘ Benjamin F. Davidson and Clarence F. Morse, Dubuque, Iowa, assignors to Mergenthaler Linotype Company, a_ corporation of New York Application May 29, 1935, Serial No. 23,984 3 Claims. This invention relates to means for prevent ing the adherence of molten metal to an object, and especially to means for preventing the ad herence of molten metal to the plunger rod of 5 machines designed to produce type bars, types, and like typographical elements. In the operation of the casting mechanism of such ‘machines, molten metal contained in a so called “metal pot” is ejectedtherefrom into a 10 mold by means of a plunger operating in the well of the pot, this plunger being carried at the lower end of a plunger rod, usually made of steel, which extends upwardly through the bath of molten metal and which is connected above the pot to 15 appropriate power devices operating to recipro cate the plunger down and up during each slug casting operation. During the reciprocation of the plunger, a cen tral section of the actuating plunger rod is mo mentarily immersed in the bath of molten metal, and in practice it has been found that each time this section is removed from the bath, metal ad heres to the upper end thereof and that the metal which thus adheres accumulates and even (CI. 22-70) ‘ried upwardly into the air where it hardens about the rod. ' In accordance with the present invention, the ‘above, as well as other di?iculties, are overcome by enveloping at least that portion of the plunger :5 rod which is in line with the level of vthe bath when the plunger is in its down position within a shield which is so constructed that the vmolten metal does not adhere thereto as it is alternately die carried into and out of contact therewith. For a clear understanding of the invention, ref erence may be made to the accompanying draw ‘ing. In the drawing, however, ‘the invention is shown merely in preferred form and by way of example, but obviously many changes and vari- 4115 ations may be made therein and in its mode of application which will be comprised within its spirit. It should therefore, be ‘understood that the invention is not limited to any speci?c form or embodiment, except in so far as such limita->._i20 tions are speci?ed in the claims. Referring to the drawing: ‘Fig. 1 is an elevational ‘view, partially in sec tion, of certain portions of a casting machine tually attains such proportions that in the de scent of the plunger rod, it strikes the surface of the bath and causes the same to splash. This action not only detracts from the efficiency of the embodying the principles of the present inven-.j225 tion; slug casting operation, but in addition,‘ the sociated shield; and splashed metal is thrown out upon adjacent parts of the machine and aside from endangering the operators and others who might be near, it ne cessitates the stopping of the machine and en Fig. 3 is a View in section, taken along the linec30 3-3 of Fig. 2. In the drawing, I0 designates a metal pot with tails a considerable loss of time in removing the splashed metal from the machine parts and in freeing the rod of the accumulated mass of metal. This accumulation of metal is believed to be due to the fact that the dissipation of heat by radiation and by conduction from the exposed ‘ upper end of the rod so reduces its temperature that the motlen metal is chilled as it is immersed therein during the casting operation; and to the further fact that the time this section is im _ mersed is insufficient to raise its temperature suf ?ciently high to free it of the metal which ad heres to it as a result of being so chilled. The metal, however, which adheres to the rod and which is carried below the surface of the bath is J reheated by the bath to temperatures sufficiently high to free it from the rod but the metal which so adheres to that portion of the rod which is in line with the level of the bath when the plunger is in its down position is not carried below the level of the bath, but on the contrary it is car Fig. 2 is an enlarged detail view, partially in section, of the plunger, plunger rod and‘its as a well H therein, and having a discharge spout [2 leading from the well and adapted to deliver molten metal ‘into a mold IS. The ejection of. 35 the molten metal from the pot is effected by means of a plunger l5 ‘movable down and up in the well ll vand operated by a plunger rod H ex tending upwardly from the plunger through the bath of molten metal and connected above thevilo .pot to suitable actuating mechanism, including a lever l6 adapted vto be operated to move the plunger down ‘and up in successive slug casting operations. In accordance with the present invention the 45 gradual accumulation of metal about the rod I5 before alluded to, is prevented by means of a shield II which surrounds and which is heat insulated from at least that portion of the rod which is in line with the level of the bath when 50 the plunger I4 is in its down position, the shield being made of a thin sheet of aluminum or other suitable metal or alloy having high heat con ducting properties to render it highly sensitive to temperature changes. In the present embodi- 55 ' 2 2,125,067 ment of the invention the heat insulation is ob tained by so constructing the central portion of the shield I1, as shown more clearly in Fig. 2, as to provide an air pocket [8 between it and that portion of the rod which it envelopes. If desired, this air pocket may be packed with suitable heat insulating material but in the pres ent embodiment of the invention this is dispensed with and the insulation offered by the con?ned 10 air in thepocket is relied on alone. The lower present embodiment of the invention, to simpli fy the construction of the shield but it is ob vious that this loss could be substantially elimi nated by the insertion of an insulating member between the shoulder and the rod, Since this gradual decrease in temperature is slight, the temperature of this portion of the shield is raised to substantially the temperature of the bath as it is brought into contact there with when the plunger is moved to its down 10 end of the shield terminates in a shoulder I9 position, this increase in temperature being due which ?ts tightly about the rod to seal the lower primarily to the high degree of response which end of the air pocket l8 against the in?ow of molten metal, and to prevent displacement of the shield has to temperature variations and to 15 the shield, as it is raised and lowered in the the fact that as the shield is immersed its heat absorbing area increases and its heat radiating 15 area decreases accordingly. Under these condi bath, the shoulder I9 is fastened ‘to the rod as by means of a pin 20. The upper end of the . tions the molten metal is not chilled sui?ciently shield I‘! likewise terminates in a shoulder 2|v to cause it to adhere to the shield as the shield which also ?ts tightly about the rod to seal the is brought into contact therewith during the re ciprocation of the plunger rod. 20 upper end of the air pocket l8 against the in 20 ?ow of ambient atmosphere. In the present em Having thus described our invention, we claim: bodiment of the invention the overall length of 1. In combination, a pot containing a bath of the shield I1 is such that the lower end there molten metal, a reciprocable plunger rod so of remains immersed in the bath when the positioned in the pot that a section thereof is 25 plunger I4 is in its raised, position as indicated alternately carried below and above the level of 25 by the full lines in Fig. 1, and the upper end the bath, and a metal shield carried by said rod, thereof remains above the level of the bath when insulated from said section by con?ned air and of the plunger is in its down position, as indicated such length that the lower end thereof remains by the dotted lines in the same ?gure. immersed in said bath and the upper end there The lower portion of the shield, being im of remains above‘the level of the bath as the rod V30 30 is reciprocated. mersed, even when the plunger I4 is in its nor mal raised position, absorbs heat from the bath 2. In a typographical machine, the combina as well as from the immersed lower end of the tion of a pot containing a bath of molten metal, plunger rod 15 and is, therefore, maintained at a reciprocable plunger rod so positioned in the pot that a section thereof is alternately carried 35 a temperature substantially the same as the tem~ perature of the bath, but the upper portion of below and above the level of the bath as the rod the shield, being exposed to the ambient at mosphere, loses heat by radiation as well as by conduction through the upper shoulder 2| to the 40 rod l5 and is, therefore, at a temperature which gradually decreases from that portion which is in line with the level of the bath and which is at a temperature substantially the same as the temperature of the bath to the upper end there 45 of. This gradual decrease in temperature, how ever, is slight, due to the high heat conducting properties of the shield and to the fact that both the heat radiating and heat conducting losses 50 are limited. The heat radiating losses are limited since they are substantially con?ned to the ex posed outer surface of the shield by virtue of the fact that the inner surface of the shield is sealed against the ambient atmosphere and to the fur ther fact that the air con?ned in the pocket I8 is maintained at elevated temperatures by heat 55 which is radiated from the immersed lower por tion of the shield and from the surrounded por tion of the rod l5. Also the heat which is lost by conduction is limited since the temperature 60 gradient between the upper shoulder 2| and that portion of the rod IS with which it contacts is slight, and since the heat which is thus lost by conduction is so limited it ispermitted, in the reciprocates, and a metal shield carried by the rod and insulated by con?ned air from that por tion of the rod which is in line with the level of the bath when the rod is in its down position, the length of the shield being such that the 40 upper end thereof remains above the level of the bath and the lower end thereof remains below the level of the bath as the rod reciprocates. 3. In a typographical machine, the combina tion of a pot containing a bath of molten metal, a reciprocable plunger rod positioned in the pot, and a metal shield positioned about the rod for preventing the adherence of molten metal there to, the upper end of the shield being secured to the rod above the level of the bath when the 50 rod is in its down position, the lower end of the shield being secured to the rod below the level of the bath when the rod is in its up position and that portion of the shield in line with the level of the bath when the rod is in its down 55 position being separated from that portion of the rod about which it is positioned and of such thinness that its temperature is raised to sub stantially the temperature of the bath as it is 60 brought into contact therewith. BENJAMIN F. DAVIDSON. CLARENCE F. MORSE.