US2471563A - Toggle press and method for molding articles from granular material - Google Patents

Description

y 1949- M. E. GATES 2,471,563

TOGGLE PRESS AND METHOD FOR MOLDING ARTICLES FROM GRANULAR MATERIAL Filed Feb. 25, 1944 5 Sheets-Sheet 1 May 31, 1949. E GATES 2,471,563

TOGGLE PRESS AND METHOD FOR MOLDING ARTICLES FROM GRANULAR MATERIAL Filed Feb. 25, 1.944 I 5 Shets-Sheet 2 fizz/5715 07": .flfCf bj E Gages May 31, 1949.

Filed Feb. 25, 1944 TOGGLE PRESS AND METHOD FOR MOLDING ARTICLES FROM GRANULAR MATERIAL s Sheets-sheaf 3 r 56 54 R v 1a1- U g Patented May 31, 1949 UNITED STATES PATENT OFFICE 'liOGGLE PRESS AND METHOD FOR MOLDING ARTICLES FROM GRANULAR MATERIAL 12 Claims.

This invention relates to the manufacture of pressed articles, made of powdered or granular materials, and among other objects aims to provide a novel process and apparatus for producing an improved product.

The nature of the invention may be readily understood by reference to one illustrative process and apparatus shown in the accompanying drawings.

In said drawings,

Fig. 1 is a side elevation, partly in section, of a toggle press;

Fig. 2 is a similar side view showing the mold shifted to charging position and about to receive a charge of clay;

Fig. 3 is a fragmentary view similar to Fig. 3 after it has received the charge of clay.

Fig. i is a fragmentary front sectional elevation taken on the plane 4-4 of the mold and press plunger;

Fig. 5 is a plan view of the mold partly in section, taken on the plane 55 of Fig. 4;

Fig. 6 is a plan section, taken on the plane 6-43 of Fig. 1, of the charging hopper and its operating mechanism; and

Fig. 7 is a sectional elevation diagrammatic in character showing the means for controlling the mold plungers and other related instrumentalities.

The invention is here illustrated in apparatus for making pressed fire brick, but it will be understood that the principle of the invention applies to the manufacture of other articles from compressed powdered or granular materials. In conventional presses heretofore employed for pressing fire brick and the like, the clay is comressed in a mold by upper and lower plungers operated mechanically or hydraulically. One eX- ample of the conventional mechanical press is the so-called Boyd press illustrated in Flood Patent No. 987,124. The Boyd press is characterized by toggle operated plungers which engage the upper and lower surfaces of the clay in the mold and which are moved vertically at appropriate times in the cycle of operations, first to control the volume of clay introduced into the mold (and therefore the thickness of the articles) and second, to raise the compressed brick out of the mold to a position where it may be removed.

In presses of this type, the mold is filled by a charger of limited capacit which slides a quantity of clay forward over the mold. The excess is dragged back by the charger whose rearwardly travelling edge levels off the clay in the mold. In refilling the charger the clay tumbles and falls into a space filled with air, resulting in uneven distribution and occlusion of an excessive amount of airinto the clay delivered to the mold. Howeverclay remaining in the charger (after a previous filling of the mold) is substantially more compact than the refilling charge. I have found that this method of filling the mold results in uneven distribution of the clay in the mold, and a mold content of relatively low density due to excessive occlusionof air in the mold.

The initial volume of clay in the mold being relatively large (due to the looseness of the clay in the mold and the occluded air therein), requires an excessive plunger movement to compress it. This aggravates the disturbance of the clay adjacent the sides of the mass in frictional contact with the sides of the mold. Moreover, the movement of the clay is not uniform. In certain regions, the clay mass, e. g., the clay at the top of the mold in contact with the molded sides, is displaced more than other portions of the clay mass; this aggravates the inequalities in the compressed brick and apparently disturbs the clay bond, for minute checks or cracks occur. These are not eliminated on firing.

Other peculiarities incident to the mechanics of the Boyd press contribute to the same result: for example, since the position of the lower plunger at the time of starting compression varies (depending upon the depth of the mold, i. e., the desired thickness of the compressed product), the location of the toggles varies with relation to the mold. The result is that there is a variation in the distance through which the clay is dragged in the mold while under compression. This has an effect on the checks or cracks which occur in the side faces of the brick.

In general the present invention may be characterized by (1) providing more effective means for moving or displacing air from the material prior to introduction into the molds; (2) introduction of the material into the mold without disturbance and in a more uniform and compact condition and (3) minimizing the disturbing and uneven friction of the compressed material with the sides of the mold and internally. The latter (3) results in part from the uniformity and compactness of the material introduced into the mold. The invention is embodied in a toggle press similar to the Boyd press but differing therefrom in important respects presently described. The toggle mechanism may be advantageously similar to that disclosed in my Patent No. 2,334,082 which is characterized by the use of a relatively adjustable intermediate link It between the main toggle arms I l and I2. As explained in my said patent the intermediate link may be shifted relative to the toggles and to the operating crank I3 to secure certain improved action of the toggles during the final compressing stages of the clay.

As in the typical Boyd press, the toggle arms are operated by connecting (so-called lifting) arms l4 which, having cam faces on their under sides, engage the rollers l5 and in conjunction with the movement of the operating crank I3 first lower the lower plunger It to gauge the depth of the mold for receiving the proper charge, and second, after compression raise the compressed article I! out of the mold l8 so that it can be removed. It will be understood that the toggle arms and lower plunger are associated with upper and lower crossheads l9 and 20 which with crosshead connecting bars 2|a slide bodily under the action of the lifting arms 14 in the side frame guides 2|. The crank I3 is associated with the main shaft 22 which in turn is rotated by a heavy driving gear 23. Rollers I are advantageously supported by short heavy springs 24 which reduce shock and relieve the upper face of the molded article of a portion of the weight of the apparatus. Also if applied to the conventional Boyd press these springs would insure raising of the compressed article out of the mold.

In the present apparatus, the hopper 28 (Figs. 1 and 6) is designed to hold a column of clay of substantial depth. Clay is introduced into the upper end 29 of the hopper by an appropriate filling spout not shown. The hopper and the mold are aligned for filling, in the present instance, by shifting the mold 18 out of its normal position to register with the hopper (Figs. 2 and 3). For that purpose the mold is slidable relative to the side frames 2| on guides 30. The lower plunger I6 is similarly slidable with the mold on guides 3| carried on the crosshead 20 (see Figs. 1 to 3). The mold operating mechanism is here represented by a lever 32 pivoted at 32 and connected by a link 33 with the mold. The lever in the present instance is operated by a S ide groove cam 34 in the groove 35 of which a roller on the end 35 of the lever travels.

Cam 34 is advantageously mounted on the main shaft 22 and the cam groove 35 is designed to shift the mold at the proper times in the cycle in relation to the operation of the press.

When the mold is in register with the hopper, the lower plunger [6 is moved downwardly as a result of a downward movement of the lower crosshead 20 (see Fig. 3). The crosshead operating mechanism will be presently described. Upon register of the mold with the hopper, the clay is released, in this instance by a slight retraction of the sides of the hopper. This allows the column of material to move down bodily and fill the mold. Preferably the sectional shape of the hopper is substantially the same as the mold, thus involving no rearrangement or shifting of clay in filling the mold. The material in the hopper is progressively compacted in its downward travel both by the weight of material above it, and, in this case, by the repeated in and out movement of the sides of the hopper.

The hopper releasing mechanism comprises in this instance separately movable sides 4| and 42 of the hopper (see Fig. 6). One pair of sides, in this instance, the sides 42, is provided with means in the form of flanges 43 which confine the sides 4- When the sides 42 are retracted slightly from the column of material, the inclined faces of the flanges 43 also relieve the sides 4!. Only a very slight outward movement is necessary to release the column of material. The hopper operating mechanism comprises in this instance pairs of toggle arms 44 and 45 hinged at 46 respectively to the sides 42 of the hopper and pivoted together adjacent their other extremities at 41. As shown in Fig. 1 toggle arms 44 connected with the remote side of the hopper are out of perpendicular with the hopper when the latter is in closed posi- 4 tion, whereas the arms 45 connected to the near side of the hopper are substantially perpendicular to such side. Therefore, when the outer ends of the toggle arms are raised in a straight line parallel to the hopper sides, their action is to separate sides 42 slightly.

The toggle arm operating mechanism is here shown in the form of solenoids 48 whose vertically movable armatures 49 are connected with the upper and lower pairs of toggles. When solenoids 4B are energized, they raise the toggles and thus simultaneously relieve the sides of the charger to release the column of clay. When the solenoids are de-energized, springs 5| and 52 force the outer ends of toggle arms and draw the sides 42 of the hopper together. The cam action of the flanges 43 similarly forces the sides 4| together. The result is a further compacting of the column of material in the hopper.

The solenoids in this instance are operated by a switch 53 controlled by a switch operating disc 54 rotated by control shaft 55. This shaft may constitute an extension of the main shaft 22 or be a separate shaft rotating at the same rate and in phase with main shaft 22. The switch operating disc advantageously carries one or more adjustable projections 56 for operating the switch at the proper time in the cycle. When the switch plunger 51 passes off the end of the projection, the solenoid is de-energized. By this means the sides of the charging hopper may be, if desired, repeatedly relieved and again closed on the column of clay each cycle so that by an action similar to vibration, the column of clay may be additionally compacted or precompressed if desired.

Air in the material may be more effectively removed or displaced in the hopper. Flexible lines 58 may apply suction to remove air or introduce steam or a gas such as butane (liquefiable at room temperature and at the pressure in the press) to displace the air. Heretofore suction has been applied to the mold alone but for obvious reasons this has not been sufficiently effective. Removal of air in the hopper of course further compacts the material introduced into the hopper and further avoids impairment of the compressed brick or other article which otherwise might ensue upon expansion of the air after release of mold pressure. The same advantage inheres in the use of an air displacing gas which liquefies upon compression of the mold.

After filling of the mold as aforesaid the latter is moved forwardly by its operating lever 32 thus cutting off the column of material by the action of the upper edge 55 of the mold. The rearwardly extending face 55 of the mold serves to close the hopper against escape of material. The mold is moved forwardly until it comes into alignment with the upper plunger 5 l. The lower plunger It moves to its initial position with the mold.

In the present apparatus the cross head 28 is vertically adjusted to gauge the depth of the mold and for other purposes presently described by a hydraulic jack comprising a plunger and cylinder 52 and 53. As stated above the hydraulic jack functions not only to control the depth of the mold for controlling the charge of clay entering the mold, but to shift the cross-head and toggles vertically relative to the mold at appropriate times in the cycle of operations. For example, just prior to the compression of the clay in the mold the cross-head and lower plunger may be shifted so as to bring the charge of clay in the mold to a fixed position regardless of the amount of clay (i. e. the'thickness of the articles compressed)" in the mold. This insures a uniform treatment of the clay in the mold regardless of the thickness of the article and also minimizes the dragging of the clay vertically in the mold while it is under compression. The latter occurs in the Boyd press as an unavoidable incident of the operation of the connecting or lifting arms in conjunction with the operating crank and lift ing rollers. Also the jack functions momentarily to relieve the upper face of the clay of the load of the toggle mechanism, thereby to facilitate de-airing of the clay, if it has not been de-aired or fully de-aired in the hopper. It will be understood. that unless an opportunity is permitted for the escape of air which has been compressed in the clay clue to the action of the plunger, the compressed air by reason of its subsequent expansion may cause checks and cracks in the clay. As explained in my aforesaid patent the action of the intermediate link in conjunction with lifting arms I l and crank 13 may momentarily relax the compression on the clay to permit escape of air and at such time the hydraulic jack may appropriately take the weight of the upper plunger and the toggle arms and cross-head off the upper face of the brick to permit escape of air from such face.

The jack operating mechanism as here shown (Fig. 7) is in the form of an auxiliary cylinder and piston 66 and 65 connected by line 10 with the jack cylinder 63. Piston 65 is operated by cam 56 on control shaft 55 through an operating rod 61. Cam 66 is designed so that at desired times in the cycle, the plunger 65 is forced downwardly to increase the hydraulic pressure in jack cylinder 83 and thereby raise both plungers in the mold. The hydraulic jack is further controlled by an unbalanced valve 68 in line 69 connecting the jack cylinder 63 with a supply tank 11 under relatively low pressure. This tank supplies hydraulic liquid and also to the extent of its pres-.

sure (while valve 68 is open) counterbalances or partly counterbalances the weight of the crossheads, toggles, etc., and to that extent equalizes the pressures of the plunger against the upper and lower faces of the material in the mold. So long as valve 58 be open, the jack is substantially functionless and moves up and down with the cross-head as the latter and elements associated therewith are moved up or down by lifting arms i l. The latter move the plunger l6 down togauge the volume of material introduced into the mold, until valve 58 closes, at which time jack 62 arrests further downward movement of the plunger and a the lifting arms simply rise above their previous fulcrum, followed in this case by the rolls I5 under the action of springs 24. Similarly, plunger s5 is ineffective in raising the jack unless valve 68 be closed.

The mechanism for controlling valve 68 is here shown in the form of a floating lever 12 whose position is determined first by the position of cross-head 29, i. e., the lower plunger I6, and sec- 0nd, by the position of lever 13 pivoted to an intermediate fulcrum point 14 of lever 12. The other end of lever 13 is supported by its pivot 15. One end of lever 12 bears against adjustable valve stem 15 and the other end engages a projection Tl which moves with the toggle frame and lower plunger is. As here shown projection 11 is connected to cross-head 20. Lever 12 is held in contact with projection 11 by spring 18. Valve stem 16 is held against lever 12 by the fluid pressure tending to close the valve. Whether valve 68 is 6 open or closed depends on the relative positions of projection 11 and fulcrum 14 (i. e. the inclination of lever 13) So long as projection 11 is out of contact with lever 12, valve 69 is held open by spring 18 which is strong enough to overcome the valve closing force of the fluid pressure; but unless fulcrum 14 be elevated in relation to projection 11 contact of the latter with lever 12 will not at once close valve 68. Periodically during the cycle, lever 13 is depressed sufiiciently to lower lever 12 so as to place valve 69 under the control of the cross head 29 (i. e. projection 11).

The mechanism for thus positioning lever 13 shown is represented by a cam roll '8! which travels between an inclined cam surface 32 (in this instance adjustable) and the upper surface 83 of lever 13. As the roll advances on the converging surface 32, lever 13 and fulcrum 14 are progressively lowered. The cam roll in this instance is reciprocated by bell crank lever 84 pivoted at 95 and bearing against cam 86 on shaft 55 against the former at which it is held by spring 81. Cam roll 8! is connected to lever 84 by a link 88. Thus at the appropriate time or times in the cycle, cam moves cam roll 8| (to the right in Fig. 7) so that in conjunction with the cam surface 82, lever 13 is depressed to a degree depending on the position of roll 8! and the inclination of cam 92. Adjustment of such inclination is effected by an adjusting screw 89. The latter adjustment determines among other things the distance plunger l6 (and projection 11) moves down before closing valve 69 for the purposes above stated. The pressure on the pressed article is therefore controlled by adjusting cam 2 wit screw 89.

To minimize disturbances of the compressed article upon ejection from the mold and to facilitate de-airing in the mold, the latter is advantageously designed to be relieved or slightly expanded at the desired time. This is efiected in this case (see Fig. 5) by allowing retraction of one or more sides of the mold upon ejection or during the compressing cycle to facilitate deairin-g. As here shown the sides 9| and 92 are movable relative to the other sides of the mold and are restored to operative position hydraulically. It will be understood, however, that a similar effect could be obtained simply by permitting the mold sides to flex or stretch at the proper time. The amount of deflection to secure the desired result need be very small.

The hydraulic operating mechanism comprises short hydraulic jacks of which the sides 9| and 92 constitute the cylinders and portions of the surrounding body of the mold provide stationary pistons 93 and 94. The long sides of the mold embodies two plungers and the short side a single plunger. Passages 95 and 95 leading to line 91 conduct hydraulic pressure fluid to the mold cylinders. Pressure is maintained in the cylinders to force the mold sides to normal position by means of a plunger 98 and cylinder 99 connected to line 91. Plunger 98 is operated by cam Hll on control shaft 55. Cam I9! is designed to relax pressure on the mold sides at appropriate times during the cycle. The pressure need not be wholly relieved. It is sufficient if it be substantially reduced over what is necessary to hold the sides in place against the very considerable back pressure created by the action of the toggle press in compressing the material. Line 91 is advantageously connected to the supply tank through line I02 so as to restore any leakage from the jack cylinders. A check valve I03 operates to prevent flow in the reverse direction upon the operation of plunger 98. The mold is advantageously vertically channelled at I04 adjacent the corners of the movable mold sides when the latter are retracted to allow any loose clay remaining in the mold to fall clear of the movable sides so as not to interfere with their return to normal position. The channels are preferably covered by the mold sides when they are in normal or restored position. Line 91 is provided with a movable or flexible connection which permits the necessary forward and back movement of the mold.

As stated above, it is advantageous after the first compression of the clay in the mold to raise the upper plunger slightly to permit de-airing. Simultaneously cam in! can advantageously relaX pressure on the mold sides to allow escape of air at the sides of the brick as well. These operations should be synchronized with the instant in the compressing cycle at which the intermediate link l0 normally relaxes pressure as explained in my aforesaid Patent No. 2,334,082.

In the manufacture of fire brick for example,

where high density is desired, it is possible bea cause of introduction of clay into the mold in compacted condition with much less occluded air, to use mold pressures much higher than have heretofore been possible, the disrupting action of objectionable quantities of air (after release of high compression) being absent. Damaging mold friction which ordinarily accompanies high pressures is also absent or substantially minimized.

It will be understood that the invention is not limited to the details of the illustrative apparatus since they may be variously modified. Moreover, it is not indispensable that all features of the invention be used conjointly since various features may be used to advantage in different combinations and sub-combinations.

Having described my invention, I claim:

1. In a press of the character described, the combination comprising a mold, a toggle frame carrying upper and lower plungers for compressing material in the mold, a hydraulic jack for controlling the position of said frame relative to said mold, means for introducing pressure liquid into said jack to elevate the same and adjustable means for relieving the pressure in said jack to limit its upward travel.

2. In a press of the character described, the combination comprising a mold, a toggle frame carrying upper and lower plungers for compressing material in the mold, a hydraulic jack for controlling the position of said frame relative to said mold, a hydraulic line for supplying hydraulic liquid to said jack, a valve controlling said line, and adjustable means responsive to the position of said frame for controlling said Valve.

3. In a press for molding articles from granular material and the like, the combination comprising a mold, a hopper for charging the mold and having substantially the same section as the mold, said hopper being adapted to hold a column of material for charging the mold, means for moving the sides of the hopper to precompress the column of material in the hopper, said sides being also movable to release the precompressed column of clay to permit it to move by gravity into the mold, and means for restrictingthe movement of the column of material into the mold to substantially less than that of a free fall so that the material moves into the mold undisturbed in its precompressed condition.

4. In a press for molding articles from granular materials such as clay the combination comprising a mold open at top and bottom, top and bottom plungers for compressing material in the mold, a hopper having substantially the same section as that of the mold for delivering material to the mold, means for aligning the hopper and mold for charging the latter, means for repeatedly slightly expanding and contracting the section of the hopper to precompress the material therein before delivery to the mold, and means for moving each plunger relative to the mold toward the center thereof thereby to minimize movement of the material in the mold during compression.

5. In a press for molding articles from granular materials such as clay the combination comprising a mold open at top and bottom, top and bottom plungers for compressing the material in the mold, a hopper of substantially the same section as said mold for holding a column of material for delivery to the mold, means for aligning the hopper and mold for charging the latter, means for repeatedly expanding and contracting the section of the hopper to compress the material therein before delivery to the mold, means for restricting the delivery of the material into said mold to less than that of a free fall so that the column of material moves into the mold undisturbed in its compressed condition, and means for moving each plunger relative to the mold toward the center thereof thereby to minimize movement of the material in the mold during compression.

6. In the manufacture of compressed molded articles from granular materials such as clay containing air, the method of reducing air in the article which comprises compressing a mass of the material containing air in a mold having open top and bottom and movable sides, momentarily relieving the pressure on the material and simultaneously relieving opposite sides of the mold to permit the compressed air to expand and escape, and then again compressing the material.

'7. In a toggle press the combination comprising a toggle frame carrying toggle arms and upper and lower plungers operated thereby, a mold open at top and bottom and adapted to receive said upper and lower plungers for compressing material in said mold, said toggle frame and plungers being bodily vertically slidable relative to said mold, a hydraulic plunger adapted to engage said frame to raise it bodily relative to said mold, and means for controlling the operation 5' of said hydraulic plunger at the desired time in the cycle of operations of said toggle arms and plungers.

8. In a toggle press the combination comprising a mold, a toggle frame carrying toggle operated plungers and adapted to compress material in said mold, said toggle frame and plungers being bodily vertically slidable relative to said mold, means for introducing a charge of material into said mold to be compressed by said plungers, a hydraulic plunger adapted to engage said frame to arrest downward movement of said frame relative to said mold at desired time in the cycle of operation of said plungers in said mold, and means for rendering said hydraulic plunger inoperative at other times in the cycle.

9. In a toggle press the combination comprising a mold, a toggle frame carrying toggle operated plungers and adapted to compress material in said mold, said toggle frame and plungers being lbodily vertically slidable relative to said mold, means for introducing a charge of material into said mold to be compressed by said plungers, a hydraulic plunger adapted to engage said frame to lift said frame to adjust the position of the charge in the mold, and means for controlling the operation of said hydraulic plunger in the cycle of operation of the press.

10. In a Boyd type press the combination with toggle mechanism movable bodily relative to the mold and adapted to apply pressure to material in the mold, comprising a mold, a lower plunger in said mold, a hydraulic cylinder and piston for limiting the bodily movement of the toggle mechanism relative to the mold to position the lower plunger in the mold at the time of charging, means for introducing hydraulic fluid into said cylinder to control the piston therein, a valve for releasing the pressure in said cylinder to permit the piston to move downwardly, and means operative when the lower plunger reaches its lower limit for closing said valve to arrest further downward movement of said piston and thereby that of said lower plunger.

11. The method of making compressed molded articles from granular material such as clay containing occluded air which comprises storing the material in a relatively dry and flowable condition in a column of the same section as the mold to be used and a plurality of times the depth of the mold so that the column holds enough material to fill the mold a plurality of times and the material is substantially pro-compressed therein of its own weight, thereby to displace a substantial amount of air therefrom by the time the material reaches the lower portion of the column, registering the mold with the bottom of the column and supporting the column by the movable bottom of the mold, moving the movable bottom down while supporting said column so that the column moves down bodily in substantially undisturbed condition until the mold is completely filled with material sufiioientl precompressed so as to require little reduction in volume in the ensuing compression in the mold to achieve its desired density, then without further pro-compressing the material shifting the mold laterally to sever the pro-compressed material in the mold from the column, then engaging the upper face of the material in the mold with a movable top of the mold and simultaneousl moving the movable top and bottom of the mold together so as heavily to compress the material in the mold with a minimum movement of the material in the mold, momentarily partly relaxing the compression to facilitate escape of the relatively small amount of residual air in the compressed material and then again applying full compression to complete the article and adding further material to the top of the column while that at the bottom is being withdrawn, thereby to facilitate pre-compression and displacement of air from the material to the bottom of the column while the charge previously withdrawn is being heavily compressed as afore said.

12. A press for molding articles from granular material containing occluded air such as clay comprising in combination a mold open at top and bottom, upper and lower plungers movable into the top and bottom of said mold respectively to compress the material therein simultaneously from top and bottom, toggle mechanism for operating said plungers to apply prolonged heavy compression to the material in the mold during each cycle of operation, a lifting arm for bodily raising said mechanism and plungers relatively to the mold, a hopper for charging the mold having substantiall the same section as the mold and of a depth several times that of the mold so that the hopper contains a column of material sufficient to fill the mold a plurality of times in succession and the depth of said column being great enough substantially to precompress the material under its own weight by the time it reaches the lower portion of the column, thereb to displace a substantial amount of air from the material before it is introduced into the mold and without consuming any portion of the compression cycle of the plungers to eifect such displacement, said hopper being laterally displaced from the axis of movement of said plungers, means for cyclically moving the mold from compressing position in alignment with the pressing axis of said plungers to a position for filling wherein said lower plunger registers with the lower end of said hopper and supports said column, said mold moving means then operating to move said mold from its position in register with said hopper to sever the column of clay at the upper surface of the mold and to carry the ore-compressed charge of material in the mold into alignment with said axis, said mold having a support for supporting said column during the intervals between registry of the mold therewith, said mechanism then operating to move said upper and lower plungers simultaneously together to compress said material from both faces so that there is a minimum movement of the material in the mold during compression and a maximum portion of said cycle is devoted to heavy compression of the material, said mechanism being adapted momentarily partly to relax compression to facilitate escape of residual air during compression, and a hydraulic cylinder and control means therefor for assuming at desired times in the cycle and independently of said lifting arm the weight of said toggles and plunger on the upper surface of said article in the mold.

MAJOR E. GATES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 449,424 MoFerran Mar. 31, 1891 837,243 McCarter Nov. 27, 1906 1,073,856 Jacobsen Sept. 23, 1913 1,168,768 Upham Jan. 18, 1916 1,202,617 Upham Oct. 24, 1916 1,335,303 Sutcliffe 1 Mar. 30, 1920 1,426,761 Norton Aug. 22, 1922 1,733,706 Widin Oct. 29, 1929 2,024,025 Child et al. Dec. 10, 1935 2,026,940 Hendry Jan. '7, 1936 2,067,401 Lassman Jan. 12, 1937 2,118,182 Flint May 24, 1938 2,301,939 Fischer Nov. 17, 1942 2,326,381 Milligan et a1. Aug. 10, 1943 2,334,082 Gates Nov, 9, 1943

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