US2389561A - Molding press - Google Patents

Description

Nov. 20, 1945;

F.'J. STOKES, JR, ETAL.

MOLDING PRESS led June 15, 1942 5 Sheets-Sheet 1 Zjwum hobs FRANCIS J STOKES, Jr.

F. J. STOKES, JR., ET AL MOLDING PRESS Filed June 15, 1942 3 Sheets-Sheet 3 FRRN C15 J. STOKESJY. LAWRENCE HJBPQLEY Patentecl Nov. 20, 1945 MOLDING mess Francis J. Stokes, Jr., Philadelphia, and Lawrence H. Bailey, Cheltenham, Pa., assignors to F. J. Stokes Machine Company, a corporation of Pennsylvania 1 Application June 15, 1942, Serial No. 447,110

12 Claims.

This invention relates to molding presses for compressing granular or powdered material in the cold state, into form-retaining shapes. The invention is useful in forming pellets, tablets and preforms, and also for forming h'ollow molded articles, such as hearing bushings, of comminuted materials are compressed by the upper punch" only, the bottom of the compressed piece is conslderably-softer'than the top. This condition has been recognized from the time when the first presses were'developed to do work of this sort.

A variety of methods have been worked out to remedy this condition. One common method is to have the lower punch move upward in the die at the same time that the upper punch compresses the material, so as to apply pressure uniformly to both top and bottom of the piece, see Stokes Reissue Patent No. 17,842. Although this method is satisfactory, it requires-a press with duplicate pressing mechanism, one for the upper and one for the lower punches, and there are complications in designing a press wherein the lower punch moves under, compression and then later ejects the finished part, these movements all being capable of easy adjustment to handle different size and different thickness pieces. Al--' though rotary type presses such as described in Stokes Patent No. 610,029,, compress material from both top and bottom, these presses-are not adaptable to the heavy pressures required for compressing materials such as powdered metals, ceramics, carbon, etc.

Another common method to achieve uniform density in the pieces is to resort to a floating die. A floating dieJs one which moves down around a stationary lower punch, during compression, and thus simulates the action of the lower punch moving upward during compression. There are various methods of operating floating dies. The simplest method is to temporarilysupport the die on. blocks and then after the upper punch has compressed the material sufliciently to build up a certain amount of friction between the material and the die wall, the supporting blocks are withdrawn and the die floats downward as the upper punchcompresses, the position of the die being determined by the frictional forces set up between the material and the die wall. This is termed a full floating die. The disadvantage of this method is that material must be compressed to a considerable extent before the die will be supported by the friction of the material, and furthermore the method is rather difflcult to work out on a fully automatic basis, such as is required for high production. In many cases, the die is supported on springs which support the weight of the die, and which permit the die to float downward as the friction of the material builds up. The objection in this case-is that the springs do not function uniformly, and the guides that keep the die in proper position in relation to the punches, often become clogged with dust and dirt which prevents them from moving freely, and as a result the die may be prevented from floating at all. A hydraulic cylinder is sometimes substituted for springs, these hydraulic cylinders being connected to an accumulator system so as to simulate the action of springs. Hydraulic cylinders are also used in some cases to actually move the die down under forced pressure, but this.

involves rather complicated hydraulic equipment, and the action is not uniform.

An object of thepresent invention is to devise a molding press employing a floating die with two cooperating plungers or punches, and embodying means for positively controlling the relative movement between the die and the two punches. By controlling the relative movements between the die and the two punches, the formed article has the same density characteristic on each side of its central transverse plane.

According to this invention, the rates of movement of the two punches with respect to the die may be made equal or unequal to control the density characteristic of the article with respect to the upper and lower ends of the article. In other words, where the two punches enter the die cavity with the same speed, the plane of lowest density will be located substantially at th'e middle horizontal plane of the article, and by making one punch travel faster than the other, the plane of lowest density in the article may be made to shift toone side or the other of the central plane.

This feature is useful for obtaining the same density ,in both ends of an article where one end is of a diiferent diameter from theother end and the sections of different diameters are of different lengths.

In the preferred form of the invention a lever system is mounted on the press, so that the downward motion of the upper punch automatically forces the die downward at the same time and in the proper relation to the motion of the punch. The lever system is designed so that the die starts to move down as soon as the upper punch enters this method is that thevdie moves in exact relation with the upper and lower punch, and consequently duplicates exactly the movements that would be obtained if the die were kept stationary and the upper and lower punches moved together at the same rate during compression. Furthermore, the die is moved positively regardless of any friction in the die guides or between the lower punch and the die.

Another feature of the present invention is that on the opening movement of the press, relative movement between the die and the lower punch is discontinued before the die leaves the lower punch, thus keeping the lower end of the die cavity closed for receiving a new charge, but

the upper punch continues its movement to the point of maximum separation of the two punch elements. Such an arrangement provides a maximum clearance between the upper punch and the die for a given separation of the two punches, thus providing adequate clearance for ejecting the molded article and for operation of the loading device.

Another feature of the invention is the provision of a core-rod which is mounted in fixed relation to the floating die and moves with the die. It is important that the core-rod be mounted for movement with the floating die, inasmuch as the molding material builds up frictional resistance with the core-rod wall Just as it does with the die wall. Heretofore, in pressesemploying floating dies, core-rods have been supported from some fixed part of the press, or else they have been mounted on springs which permit the rod to move downward as the material builds up resistance around it. Such arrangements are not altogether satisfactory for the reason stated heretofore in discussing stationary dies and spring-mounted dies.

Another object is to provide a compressible section in the operating connection to the movable punch of the press to secure uniform density of the molded articles and to prevent breaking of the press in the event of excessive pressures being developed during molding. For this purpose, a compressible link is provided and is normally maintained in extended position by fluid under pressure supplied from a pneumatic accumulator cylinder. ments, the fluid under pressure has been supplied through a flexible tubing connected to a moving part of the press. Such arrangements are hazardous as the tube is likely to break at one time or another, and particularly inasmuch as it must flex with each stroke of the press. This difllculty is overcome in the present invention by providing an accumulator cylinder of relatively small size operating athigh pressure and mounting the cylinder directly on the compressible link so that it moves therewith.

A preferred construction of our invention and certain modifications thereof are illustrated in the accompanying drawings in which Figure l is a side elevation of a press embodying the preferred construction, the details of con.

struction of a compressible link forming part of the operating toggle for the press being shown in section;

Figure 2 is a front elevation of the press shown in Figure 1, with the feeding device removed;

Figure 3 is a fragmentary view showing the details of construction of the cooperating mold parts, part of the view being a sectional view taken along a central transverse plane as viewed from the left side of Figure 1; and

Figures 4 and 5 are fragmentary views showing, in side elevation, modified arrangements for positively moving the floating die member at a definite speed related to the movement of the reciprocating punch.

Referring to the drawings. the press has a main supporting frame indicated generally by reference numeral l. Preferably the frame is formed of a single casting having two vertical side members I a and lb joined at the top by a portion lo and at the bottom by a portion Id. A power shaft 2 is journaled transversely of the two frame members la and lb near the top of the frame as shown. This power shaft is driven from any suitable source of power through suitable speed reducing gears or pulleys, not shown. A platen 3 of the press, preferably the upper platen, is mounted for vertical reciprocation by a suitable connection to the power shaft 2. In the construction shown, the platen 3 is provided with parallel vertically extending bosses or arms 3w'and 3b on opposite sides thereof and positioned in suitable guiding grooves formed in part by guide plates 3a and 3b secured to frame In previous arrangeconnected links.

members la and lb respectively. Various connections may be employed for translating the rotary movement of the power shaft 2 into reciprocating movement of platen 3, but the preferred construction shown in the drawings involves a toggle and crank arrangement. The platen 3 is supported from the frame I by a. toggle construction consisting of two pivotally The first link 4 of the toggle is pivotally supported at its upper end on a pintle .la supported by the frame I, and the lower end of link 4 is pivotally connected by means of a pintle 4b to the second link of the toggle which in turn is pivotally connected to the platen 3. The second link of the toggle is formed of a special construction which permits a shortening of the link when the pressure developed on the platen exceeds a predetermined limit. It is obvious, of course, that a rigid link may be employed if desired.

The second link of the toggle is shown in section in Figure 1. It consists of two sections connected together in telescopic relation and includg a hydraulic piston for forcing the two sections apart under a predetermined pressure. In the construction shown, the second link involves a cylinder 5 pivotally connected at its lower end to the platen 3 by means of a pintle 5a.. Mounted within the cylinder 5 is a piston 5b,

- end of the piston rod 511 is provided with a connecting head ie which is pivotally joined to the linklbyapintle 4b. Thepistonrodldisprovided with a flange Id by which the rod may be rotated to adjust the length of the second toggle link, it being understood that the piston rod id is rotatable with respect to the head 5e while remaining connected thereto.

A pressure chamber if is mounted on the her is partly filled with oil or other fluids shown, and the space above the oil is filled with a suitable gas under pressure. The procedure for filling chamber if is eriplained hereinafter.

The pintle lb is connected by a link 8 to a crank (or cam) in. driven by or embodied in the power shaft 2. Rotation of the shaft 2 causes the end of link 6 to travel around the circle 2a" which represents the path of travel of the crank pin to, and this movement of the link 6 causes the toggle I-5 to operate between the extended and collapsed positions, thus causing platen 3 to reciprocate vertically.

A floating die table I is mounted for vertical movement below the platen 3 and is guided by a pair of parallel guide rods 8a and 8b passing through sleeves Ia and lb on die table I and being secured insuitable bosses la, la" and lb,

lb" provided on vertical frame members In and lb respectively. Die table I is normally urged upwardly by a pair of coil springs 92 and El) surrounding guide rods 8a and 8b and resting on lower bosses Ia" and lb". The upward movement of the die table is limited by one or more set screws Ic having threaded engagement with the die table I and arranged to bear against fixed in position within the. cavity by means of a abutments Ie carried by the vertical frame membars. The normal position of the die table I may be adjusted by adjusting the stop screws Ic. The die table I carries the die part III of the mold which in the example illustrated consists of a simple cylindrical element III.

The upper punch Illa is carried by platen 3. For molding annular rings of material, this punch assumes the form of an annular member as shown.

The lower member or shaft II mounted in a vertical position in the base of the frame in line with the die In. Shaft II is guided for vertical reciprocating movement by a bearing Ila formed in the base Id of the frame, and also by a suitable hearing formed in the die table I. vA portion of the shaft is threaded as shown at I lb, and an adjustable nut He is mounted on the threaded portion main stationary for the major portion of the molding cycle, but moves the shaft upwardly, after the article has been formed, for the purpose of ejecting the article, and then returns the shaft to its normal position before a new charge of material is supplied to the die cavity. Nut He should be adjusted so that the upper end of punch Ilb is flush with the surface of table I when cam It operates the punch to its upper position.

In the formation of solid articles, the lower punch Illb carried by the upper end of shaft II would be a solid punch having the shape of the lower face of the article. In the formation of hollow articles, it is necessary to provide a core member which remains stationary with respect to the die II carried by the die table I. Where it is desired to mold hollow articles such as annular rings, as in the machine illustrated, it is necessary to provide a core-rod t3 supported centrally of the die III and in fixed relation to the die and die table I. For-supporting the core-rod I3, a crossbar Illa is positioned in a longitudinal slot.

'Hd formed in shaft III and is adjustably sup-' ported from die table I by a pair of tie rods lilb and lie. The core-rod i3 is removably secured to the crossbar I31; and its upper end lies in the common plane of the upper surface of die table I and the upper end of die It. With the construction described immediately above, it is clear that shaft l I may be reciprocated vertically to eject the article while the core-rod i3 is held in fixed relation with respect to the die lll.

The lower end ofahaft it extends into a cavity lid formed in the base of'the frame and normally rests upon a plate ll positioned in the cavity lld', see Figure 3. The plate It is helg pa of set screws Ma and lib having threaded engagement with the plate and abutting against the upper wall of the cavity. For the purpose of adjusting the height of the plate It, one or more shim plates He may be inserted beneath the plate I4. This construction provides for adjustment of the normal position of the lower punch Illb within the die III, thereby fixing the volume 4 of the charge-receiving cavity, the position of the lower punch being varied by varying the thickpunch Illb is carried by a tubular '-ginsto ness or number of shim plates Me. It will be understood that die table I may also be adjusted with respect to shaft II to vary the volume of the charge-receiving cavity.

As the punch Illa moves downwardly and becompress the material in die lllyit is desired to positively move the die table I downwardly simultaneously and at a speed having a predetermined relation to the speed of movement of the punch Illa. The preferred arrangement of the shaft. Shaft II is moved upwardly by means of a rocking lever l2 pivotally mounted on an axis lie in the base of the frame I. The lever I2 is bifurcated at the forward end, and the two arms I2a and I2!) are'positioned on opposite sides of shaft I I and engage the undersurface of nut lie. The shaft I l remains stationary durfor securing this result will now he described. A pair of brackets I50. and lib are adjustably supported on rods 8c and 8b by sleeve elements forming part of thebrackets, and a. shaft I5 is journaled in bearings carried by these brackets, the shaft being arranged somewhat forward of the press as shown in Figure 1. A lever I50 is keyed to the shaft l5 and extends back towards the press and into the-.space between the platen 3 and the die table I. A roller ltd is mounted at the end of lever I50 in the path of an adjustable abutmentscrew 3c carried by upper platen 3. A pair of parallel arms or levers use and lGb are keyed or otherwise fixed to the ends of shaft I5, and the free ends of these levers are provided with rollers IGa' and lBb' which enga e the upper surface of die table I as shown in Figure 1.

to open the mold, and additional -by'ejecting the molded article from Levers lic, lid and lib are maintained in fixed relation with respect to each other, but are rotated about the axis of shaft I! by movement of the platen 3 after engagement of screw 30 with roller lid. on the downward stroke of platen 3, the platen first takes up the gap between stop screw 30 and roller lid on lever I 50. Contact between these two elements is arranged to occur substantially simultaneously with the entrance of the punch 10a in the die 10. Further movement of platen 3' forces levers I50, Ilia and l6b to rotate in a clockwise direction about the axis of shaft l5, and rotation of levers Ilia and I 6b forces die table 1 and die I!) downwardly at a predetermined speed related to the speed of platen 3. Where it is desired toform the molded article with a symmetrical density characteristic from each end, the table I should be lowered at substantially one-half the speed of movement of platen 3, and this relation will be obtained where arms Ilia and I6b have an effective length equal to substantially one-half the effective length of lever ic. With such an arrangement, the transverse plane of lowest density in the molded article will fall substantially at the middle of the article. If it is desired to shift this plane towards one end or the Other of the article, this may be done by varying the length of -arms Na and the lib with respect to the length of the arm I50.

Sleeves la and lb are maintained in any desired position by suitable set screws threaded in the sleeves andengagingthe guide rods 8a and 81). These set screws need not be relied upon entirely to withstand the upward thrust of springs 9a and 9b when the platen 3 is moved upwardly stops are Drovided on rods 8a and 8b in the form of collars 8c and 8d adjustably clamped to rods 8a and 81) respectively. These collars are provided with stop screws 80' and 8d end of the sleevessupporting brackets H11 and i5b. It will be seen that the upward thrust of springs 9a and 9b, and the upward thrust of shaft ll during election of the molded article, is taken up by adjustable stops 1e, 8e and 8d.

For the purpose of supplying molding material to the die I 0, a hopper I1 is suitably supported from the die table 1 and is movable therewith. The lower end of the hopper is provided with an oscillating shoe I 'Iawhich has its discharge end in contact with the upper surface of die table 1 and isnormally closed by the die table. A suitablecam and lever arrangement operated by shaft 2 causes the feeding shoe to shift into a having threaded engagement therewith and positioned to engage the upper posithm over the die cavity when the upper punch [0a has been raised a certain distance above die I; and, after shaking the shoe to fill the cavity with molding material, the cam returns the shoe to one side of the cavity where it remains until another feeding operation.

After the die cavity has received its charge of material, the platen 3 moves downwardly and compresses the material in die II by the punch Illa, the die I0 being simultaneously lowered with the downward movement of the punch. During the return movement of platen 3, and after the" punch Illa has been withdrawn from the die cavity, the cam 21) lever l2 and cause il until the upper end of lower punch lllb comes flush with the upper surface of the die Hi, therethe die ID. The next operation of the feeding shoe pushes is eifective to operate rocking the upward movement of shaft is pumped into chamber the molded article to one side and into the chute 'ld formed at one side of the die table I. This chute conducts the molded article to a suitable receptacle. not shown.

In operation of the press, molding material may become lodged in the clearance space between the die l0 and the lower punch llb and prevent the punch from returning to its normal position by the action of gravity after each election operation. For the purpose of securing proper return of the lowe punch to its normal position after each ejection, the punch is normally biased downwardiy by means of a pair of springs Ila and Ilb, acting on a pair of levers "a and lab ivotally supported on, bosses la" and lb" respectively. The inner ends of lever Na and l9b press downwardly against a pair of pins 20a and 20b set in shaft I I. 'Any other suitable arrangement may be employed to return shaft II to its normal position; for example, instead of using springs, a suitable cam operated by shaft 2 may be used to positively return the shaft to its position.

The pressure developed between cylinder 5 and piston 5b from the pressure chamber 5! should be sufficiently large to prevent shortening of the lower toggle link where the molding pressure does not exceed the normal pressure required for the molding operation. If, however, platen 3 meets a resistance in excess of the normal molding pressure, the pressure developed within chamber 5! should permit piston 5b to advance in cylinder 5 and thus avoid breakage of the mold parts or parts of the press. The amount of pressure to be developed in chamber II will, of course, depend on a number of factors such as the molding pressure and the effective area of piston 5b. Since the piston 5b is embodied in the link construction of the toggle, it is desirable to reduce the size of the piston as much as possible, and it is also desirable to use a pressure chamber U of small volume. Accordingly, these considerations call for a relatively high pressure within. chamber If, and such high pressures may be obtained by the following procedure. Before introducing the liquid in accumulator chamber 5f, the chamber is first filled with nitrogen gas from a commercial container in which the gas is stored at a pressure of about 2000 pounds After this, and while the gas 5! is maintained at approximately 2000 pounds per square inch, oil or other suitable sealing liquid 5) under pressure. The pumping of the oil into chamber 5f causes a further compression of the gas within the container, and by such procedure it is possible to double the pressure or to increase it to any desired amount within the limits of the press.

In Figure 4 is shown a modification of the arrangement for securing positive movement of the die table during the compression stroke. In this figure, elements which correspond to like elements in Figures 1 and 2 are indicated by like reference numerals. The die table 1 is normally urged upwardly against adjustable stops 1c-le and -811 by springs and 9b, as in Figures 1 and 2. The arrangement for moving the die table downwardly against the action of springs 9a and 9b involves a lever 2i pivoted at an intermediate point 2la to die table I. A roller 2lb is provided at the inner end of lever 2i and arranged in the path of travel of adjustable screw- 3c carried y blaten 3 or an extension thereof. The outer end of lever 2| is restrained against rotation about the axis 2Ia by a link 22 pivotally connecting the left end of lever 2| to a suitable t by screw 30 substantially simultaneously with the entrance of the upper punch into the die. If

the pivotal axis 2|a is arranged midway between the point of connection of link 22 to the lever 2| and the pivotal axis of roller 2lb, then lever 2i will cause die table I to move downwardly at 'onehalf the speed of the downward movement of. platen 3. By shitting the point of pivotal connection between the die table and the lever 2| so as to vary the lever arms on opposite sides of the pivotal point, the relation between the speed oi movement of the die table I with respect to the platen 3 may be varied.

Another possible arrangement for securing posi-- tive downward movement of the die table I at one-half the speed of platen 3 is illustrated in Figure 5. In this arrangement, the die table is urged upwardly against adjustable stops in the same manner as in Figure 4. Instead of using a lever for lowering the die table by movement of the platen 3, a spur gear 23 is rotatably mounted on die table 1 and is positioned between and engages two racks 24 and 25. Rack 24 is secured to a fixed part of the frame and passes through a guide 24:: secured to the table 1. Back 25 is arranged parallel with rack 24 and is guided by a pair of guides 25a and 25b carried by table 1, the rack 25 being positioned directly in the line of travel of screw 3c carried by platen 3 or an extension thereof. In actual practice, the arrangement involving the elements 23, 24, 25, etc., would be duplicated on the opposite side of the table I.

In the operation of Figure 5, during downward movement of the platen 3, screw 30 will engage the upper end of rack 25 substantially at the same time that punch I Ila enters die It, and thereafter the die table I will be driven downwardly at one-half the speed of movement of the platen 3. By using a double-gear instead of the single gear 23 and having rack 24 engage one part of the double gear of one diameter and raclr 25 engage the other part of the gear of a different diameter, it is possible to fix the rate oi movement of the table I to have any desired relation to the speed of platen 3. V

Certain advantages are obtained in returning the die table I to its upper position by means of springs 9a and 9b and limiting the upward movement by means of adjustable stops, one advantage being that a greater clearance space is obtained between the upper punch Illa and the upper surface-of die table I when the platen is in its upper position, thereby facilitating the loading or feeding operation.

Also, the die table is held stationary and in fixed relation .with respect The pressdescribed herein is adaptable for the molding of a variety of articles of different shapes and sizes. It is obvious that the mold parts In,

Ila and "lb may be modified to produce articles 01 different shapes, either solid or hollow. The

volume of the charge-receiving cavity may be adl4, or by adjustment of the length of the lower link in the toggle 4-5.

In the constructions described herein, the die table I as well as the die I0 is positively moved towards the stationary punch, but it is obvious that the table 1 may remain tationary and it is only necessary for the die H! to be movable towards the stationary punch. An obvious modification of the invention would involve an arrange-.

ment where the table I is adjustably secured to guide rods 8a and 8b, and the die It! is slidably mounted in a bore formed in table I in line with upper punch Illa, the die being urged upwardly against an abutment by a suitable spring to normally hold the die in its upper position with its upper end fiush with the upper surface of table I. The die would be moved downwardly against the action of the biasing spring by a suitable connection between the die and lever arms i611 and 16b.

The springs 9a and 911 may be omitted, and the die table 1 may be returned to its normal position by a suitable connection to the upper punch.

While the invention has been shown in connection with atoggle type of press, it will be understood that the invention may be applied to any type of reciprocating press. Also, while the illustrated embodiments of the invention employ only a single-acting upper punch and single-acting lower punch, the invention is useful in presses having multiple-acting upper or lower punches wherein one punch is movable within another.

What we claim is:

1. A molding press comprising, in combination, a reciprocative die having a mold cavity in the form of a bore therethrough, a normally stationary punch positioned in one end of said cavity, means for normally holding said reciprocam tive die in a predetermined cavity-forming position with respect to said stationary punch, a reciprocative punch positioned to enter the other punch.

2. A molding press comprising, in. combination, a reciprocative die having a mold cavity in the form of a bore therethrough, a normally stationary punch positioned in one end of said cav- .ity, biasing means acting in a direction to separate said die and stationary punch, means for limiting the separation of said die and stationary i punch and for normally holding said elements in to the lower punch during the loading operation.

cavity-forming position, a reciprocative punch positioned to enter the other end of said cavity, means for cyclically driving said reciprocative punch into said cavity and for withdrawing the same therefrom to permit filling of said cavity, and speed-reducing driving means controlled by the movement of said reciprocative punch towards said die for positively mo ving said die towards said stationary punch ,at a speed bearing a definite relation to the speed of movement of said reciprocative'punch.

3. A molding press comprising, in combination, a reciprocative die having a mold cavity formed therein, a normally stationary punch positioned in one end of said cavity, means for normally holding said reciprocative die-in cavity-forming position with respect to said stationary punch, a reciprocative punch positioned to enter the other end of said, cavity and to be withdrawn therefrom to permit filling of said cavity, driving means for moving said reciprocative punch to enter said cavity, driving means comprising a mechanical movement for positively moving said reciprocaper punch, means for mounting and guiding said upper [punch for vertical reciprocating movement to enter the upper end of said cavity and to be withdrawntherefrom to permit filling of said cavity, driving means for reciprocating said upper punch through a molding cycle, driving means for moving said die towards said lower tive die towards said stationary punch at a speed less than the speed of said reciprocative punch,

a and means for timing the operation of said two driving means whereby said second driving means becomes efiective substantially at the instant when said reciprocative punch enters said cavity.

4. A molding press according to claim 1 wherein saiddie moving means comprises a pivoted lever having an arm thereof arranged in the path of travel of a part moving with said reciprocative punch and being oscillatable thereby, and

- 'a'connection from said lever to said reciprocating die against the action of said biasing means.

6. A'molding press according to claim 1 wherein said die moving means includes a movable operating element positioned in the path of travel of a part moving with said reciprocative punch and'b'eing engaged by said part at substantially thejinstant when said reciprocative punch ente'rs' said die. 1

7. A molding press comprising, in combination, a die table witha die mounted thereon having a mold cavity open at the top and bottom, means for guiding said die table for vertical reciprocatiom'a lower punch positioned to close thelower end of said cavity and being mounted forjvertical reciprocation into said cavity to eject am'olded article therefrom, means for normally biasingv said lower punch downwardly against a stop}. means for normally biasing said die table upwardly against a stop to normally maintain said' die table in a predetermined position with respect to said lower punch, an upper punch, means for mounting and guiding said upper punch for vertical reciprocating movement to enter the upper 'end of said cavity and to be withdrawn therefrom to permit filling of said cavity,

- an oscillatable pivoted lever, a connection from said pivoted lever to said die table for reciprocating said table by oscillation of said lever, and an element movable with said upper punch and positioned to engage and oscillate said lever on the downward movement or said punch.

8. A molding press comprising, in combine-.- tion,.a die havinga mold cavityopen at the top I and bottom, means for guiding said die for vertical reciprocation, a lower punch positioned to close the lower end of said cavity and being mounted for vertical reciprocation into said cavity toeiect a molded article therefrom, means for normally biasing said die upwardly against a stop to normally maintain said die in a predetermined position with respect to said lower punch, an uppunch against said biasing means at a lower speed than the speed of movement of the upper punch on its downward movement, means for timing the operation of the second driving means with respect to the first driving means whereby the cycle of movement of said die begins substantially at the instant when the upper punch enters the die and ends substantially at the instant when the upper punch leaves the die.

9. A molding press comprising, in combination, a die having a mold cavity formed therein,

a normally stationary punch positioned in said cavity and having a longitudinal bore formed therein, means for mounting said die for reciprocation with respect to said normally stationary punch, a core-rodpositioned within the bore of said punch and extending into said die, and means for supporting said core-rod in fixed re-, lation to said die, whereby said core-rod reciprocates with said die.

10. A molding press comprising, in combination, a die having a mold cavity formed therein,

a normally stationary punch positioned in said cavity and having a longitudinal bore formed therein, means for mounting said die for reciprocation with respect to said normally stationary punch, a core-rod positioned within the bore of said punch and extending into said die, and means for supporting said core-rod from said die support in fixed relation to said die while permitting reciprocation of said punch to eject a molded article from said cavity.

11. A molding press comprising, in combination, a die having a mold cavity formed therein, a reciprocative support for said die, a normally stationary punch positioned in one end of said cavity and having a longitudinal bore-formed therein, a core-rod positioned within the bore of said punch and extending into said die, means for supporting said core-rod from said die, support in fixed relation to said die while permitting reciprocation of said punch with respect to said die to eject a molded article from said cavity, a

reciprocative punch positioned to enter the other end of said cavity and to be withdrawn therefrom to permitfilling of said cavity, driving means wherein saidstationary punch has an'axial bore for moving said reciprocative punch to enter said cavity, driving means for moving said reciprocative die towards said stationary punch at a speed less than the speed of said reciprocative punch, and means for timing the operation of" said two driving, means whereby said second driving means becomes effective substantially at the instant when said reciprocative pimch'e'nters said cavity.

12. A molding press according to claim 1 formed therein, and including a core-=rod positioned in the bore of said punch and extending into said die, and means for supporting said corerod in fixed relation to said die.

. J, s'roxns, JR.

L. H. BAILEY;

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