US3374513A - Pressure forming system - Google Patents

Description

March 26, 1968 c. J. KELLEHER PRESSURE FORMING SYSTEM 2 Sheets-Sheet 1 Original Filed Jan. 14, 1963 INVENTORI CORNELIUS J. KELLEHER @MW 1 W ATTORNEY March 26, 1968 c. J. KELLEHER 3,374,513 I PRESSURE FORMING SYSTEM 2 Sheets-Sheet 2 Original Filed Jan. 14, 1963 m Qfm United States Patent 3,374,513 PRESSURE FORD/ENG SYSTEM Cornelius J. Kelleher, Dallas, Tern, assignor to Verson Manufacturing (10., Dallas, Tern, a corporation of Texas Griginal appfican'on Jan. 14, 1963, Ser. No. 251,166.

Divided and this application Oct. 22, 1955, Ser.

Claims. (Cl. -23) This is a division of my copending application Ser. No. 251,166, now abandoned, filed Jan. 14, 1963.

This invention relates to pressure forming and, more particularly, to a system for continuously forming ceramic bodies.

The production of ceramic Ware such as pottery, dishes and the like has been accomplished by several methods including slip casting and plastic forming, as well as pressure forming. Machines have been developed which are automated or semiautomated with the result that substantial uniformity of product may be achieved. However, many articles such as large plumbing fixtures, lavatories, water closets and the like generally formed by slip casting require long curing periods. This results in relatively low production rates and a somewhat nonuniform product because multiple molds are required to accommodate the long curing periods.

The present invention is directed primarily to production of bodies such as ceramic products whereby uniformity is assured and at the same time a substantial increase in production rates may accrue. The invention is characterized by the use of a relatively thin mold liner which serves as a container for a charge to be formed and which may be moved from one treating station to another. At each such station the liner nests in a rigid mold to provide support to the liner and thereby primarily control the product configuration. At each such station a forming die is forced under pressure into the mold and its nesting liner to distribute the charge into a cavity formed between the die and the mold liner.

More particularly, in accordance with the present invention, there is provided a method of forming a moldable charge in a shaped mold which includes the insertion of a metallic liner and a charge of a workable material into a mold. Thereafter a die is inserted under high pressure into the liner for substantially uniform spacing from the walls of the liner to flow the charge into a shell of substantially uniform thickness in the cavity between the liner and the die. There is maintained a lubricant film at elevated temperature between the die and the charge. Thereafter the die and the liner are successively extracted from the mold.

In a further aspect of the invention there is provided at least two fixed molds of like configuration, each adapted to receive a mold liner in a nesting relation. A liner having a charge while in a first of the molds receives a pressure-driven die to preshape the charge therein to a central mound in the bottom thereof. Thereafter the die is withdrawn and the liner is nested in a second of the molds. A second die is then inserted into the liner to create a cavity of substantially uniform thickness along the bottom and side walls of the liner to flow the preshaped charge into said cavity in avoidance of entrapment of air in the shaped charge. Thereafter the die and the liner are successively extracted from the second of the molds through the assistance of lubricant film on the surface of the die which is maintained at elevated temperature.

In a still more specific aspect of the invention there is provided a forming system having a base and a platen supported above the base for movement toward and away therefrom. A plurality of rigid fixed molds are mounted "ice on the base below the platen each having the same inner configuration. A thin-Walled metallic mold liner is provided for nesting in the fixed molds. Dies mounted on the platen are positioned to mate with the fixed molds at spaced stations therebeneath. A first of the dies has minimal clearance from the side walls of a mating mold liner and substantial clearance at the bottom thereof for preforming a charge in the liner. A second die has uniform spacing from the bottom and sides of a mating mold liner when the platen is at a low point in its traverse Preferably, means are provided which are operable in synchronism with retraction of the platen to move each liner from registration with the first of the dies to registration with the second of the dies.

For a more complete understanding of the present invention and for further objects and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a front view of one embodiment of the present invention;

FIGURE 2 is an end view of the system of FIGURE 1;

FIGURE 3 illustrates the trajectory of movement of the liner system of FIGURE 1;

FIGURE 4 is a perspective view of a mold;

FIGURE 5 illustrates progressive forming both in longitud nal and lateral cross-sectional views of a tank and lid combination;

FIGURE 6 is an enlarged fragmentary view of the die, liner and mold at a preform station; and

FIGURE 7 is an enlarged fragmentary view of a die, liner and mold at a shaping station.

eferring now to the drawings, FIGURES 1 and 2 illustrate a hydraulic press system for forming a water closet tank and a lid therefor.

The present invention relates generally to pressure forming operations. For the purpose of describing the invention an example will be employed in which a relatively deep thin-walled container and a shallow lid are formed from a semi-dry clay body into unitary thinwalled containers. The containers thus formed may then he fired or otherwise cured, it being understood that provision is made in die shapes and dimensions to accommodate for shrinkage. More particularly, in FIG- URE 1 a hydraulic press includes a base frame it) in a floor Illa. Corner posts 11 are supported by frame 19. The posts 11 support a crown 14 which in turn supports a platen 15 by means of a hydraulic cylinder 16. Posts 11 serve as guides for the platen 15. The floor Illa serves as the bed of the unit. The platen 15 moves toward and away from the bed under the control of timer unit 14a which controls an hydraulic system such as is well-known to those skilled in the art. Suitable systems are disclosed in the catalog 1-1-52, 1952, of the Verso-n All Steel Press Company, of Chicago, Ill.

In accordance with the present invention, a plurality of molds are positioned beneath platen 15 to form relatively thin-walled bodies of the type above described from a pliable matrix. A stepwise forming operation is carried out. While a variety of different products may be formed by use of suitable dies in the unit of FIG- URES 1 and 2, the system shown is an embodiment of the vinvention for producing water closet tanks and lids from a semi-dry clay mixture.

More particularly, there is provided a series of operating stations A-F. The mix is loaded in measured amounts into a thin-Walled mold liner at station A. The liner is then moved progressively from station A to station F. The clay charge is progressively molded into the form of the product desired. The unit illustrated in FlGURE l and 2 is shown with the liners and dies in fully retracted position and ready to be transported to a next succeeding station.

7 Station A is a loading station having a holder into which a mold liner 21 is placed. The liner 21 is loaded while at station A. A clay mix issues from a preparing and storage unit 22 by way of a suitable pump 23, the output line of which, the line 24, leads by way of valve 25 to a pair of output spouts 2:5 and 27.

The liner 21 has a relatively deep pocket 21411 and a shallow pocket 21b to form a tank and lid respectively. The pocket 21a has an inner surface configuration corresponding with the outer surface of the tank to be formed. The inner surface of the pocket 21b corresponds to the outer surface of the tank lid. The liner 21 is a thin-walled shell, preferably formed of metal with an inner surface the character of which corresponds with the finish desired on the final product.

The station B is a de-a-iring station. While at station B the liner is vibrated to reduce the air content in the charge therein.

The station C is a molding station in which the charge in each of the pockets 21a and 21b is p-reshaped so that the final shaping operations will be relatively free from entrapment of air within the clay body as it is formed.

Stations D and E are forming stations in which the clay bodies are given their final form.

At station F the liners are unloaded and placed on a product conveyor belt 30.

In FIGURE 1 mold liners 21 and 31-35 are suspended on a transport unit which includes a pair of elongated cylindrical rods and 41. The rods 40 and 41 are supported for slide movement in troughs 42 and 43, respectively. The troughs or guides 42 and 43 are secured as by suitable bolts or other means to the lower surface of the platen 15. As shown in FIGURE 1, the guide 42 spans the distance between the posts 11 and 12. A plurality of hangers depend from the rods 40 and 41. A first pair of hangers including the hanger 46 is secured to the rod 40 and supports a bar 47. Bar 47 includes hooks for engaging the lip of the mold liner 21. Similarly, a pair of hangers 48 and 49 support a bar 50. The bar 50 includes hooks engaging the lip of the liner 31. Similarly, bars 51-54 are provided for movement with the rod 49. Similarly, six pairs of hanger bars and six pairs of bars such as the bar 59 are provided as appendages to the rod 4 1.

Arms 56 and 57, FIGURE 2, extend downwardly from the right-hand ends of the rods 49 and 41, respectively, and are coupled together by a spring 599 which serves to maintain the bars 54 and 54a in contact with the sides of the molds to engage the lips of the mold liners.

At station C a pair of preforming dies 60 and 61 are attached to the lower face of the platen 15. The dies 60 and 61 respectively preform the clay body into a shape suitable to be worked at succeeding stations.

Above station D a second pair of dies 62 and 63 are secured to the lower sun-face of the platen 15 and have .surface configurations which conform to an intermediate shape of the clay body. The intermediate shape is somewhat between the preform body emerging from station C md the final configuration of the body to be formed.

A final pair of dies 64 and 65 are secured to the lower surface of the platen 15 above the station E. Dies 64 and 65 have outer surface configurations which conform precisely to the inner surface configurations of the tank and lid, respectively, to be formed.

The platen 15 is driven to follow the liners 21 and 51-35 downward and then to force dies 69-65 therein.

The transfer rods 40 and 41 are moved in synchronism with the platen 15 by means of a hydraulic cylinder 70. The cylinder 70 is actuated under the control of a valve 71 which applies pressure from a supply line 72 to the control lines 73 and 74. The valve 71 is actuated in synchronism with movement of the platen 15 under control of timer 14a. The piston 75 is coupled to a member 76 which in turn is secured to the bar 40. In similar manner a drive system is provided for bar 41. By this means the bars 40 and 41 will be reciprocated longitudinally of the press of FIGURE 1. The bars 40 and 41 will travel vertically with the platen so that the trajectory of the transfer system may be as illustrated in FIGURE 3.

At each of the stations A-E there is a receptacle to receive the mold liners. At stations C and D the receptacles are fixed molds of the type illustrated in FIGURE 4. A meld 81 is poured in a container 80. A pair of pockets 81a and 81b are formed in the mold. The pockets 81a and 81b have configurations and are oriented one with respect to another so that they will provide a nest for members such as portions 21a and 21b, respectively, of the mold 21. The outer walls 82 and 83 of the container are beveled as at sections 84. The bars 54 and 54a are toothed to mate with the beveled sections 84. Thus, as the platen 15 is lowered from the position illustrated in FIGURE 1, the mold forms 21 and 31-35 are lowered into the holders at the respective stations A-E. When the mold liners are completely nested, the further downward trajectory of the platen 15 causes the bars 54 and 54a to be moved outwardly so that they will then slide downwardly along the outer surface of the mold containers. During this continued downward movement, the dies 612-65 move down into the molds to form the charges therein. As the platen moves upward withdrawing the dies 6t)65, the bars 54 and 54a slide upward along the surface of the containers at stations AE. When the dies 60455 are clear of the mold liners, spring 58 urges teeth such as on the bars 54 and 54a into engagement with the lips of the liners. As the platen continues its upward movement, the liners are lifted from the molds and elevated to the position illustrated in FIGURE 1. At this point the cylinder 70 is actuated to move the rods 40-to the right as viewed in FIGURE 1 a distance equal to the spacing between stations. The platen is then lowered to place each mold liner in the holder at the next succeeding station. As this is done, an empty liner is placed in the holder at station A and is loaded with body material. At the same time, the liner 35 is placed on the conveyor 30 for delivery to a curing station. a

In some operations one or more of the stations may be eliminated. Stations D and E are both described as forming stations in which the preformed body emerging from station C is worked to intermediate form at station D and is then worked to a final form at station E. Station B has been described as a de-airing station. It may be possible to eliminate entirely stations B and D. In pressure forming fiat ware, one may eliminate all but stations A and D. However, in the form shown in FIGURE 1, each charge of body material in each liner is progressively treated as it is moved through the press system.

Movement of the transfer system of FIGURE 1 is illustrated in FIGURE 3. The system is at a point represented by point 86, FIGURE 3. Actuation of the cylinder 70 moves the transfer mechanism to the right to point 87 while the platen 15 is elevated. At point 87 the press is actuated to lower the platen 15. As the platen is lowered to point 88, the liners become completely nested within the molds. Continued downward movement of the platen is accompanied by movement of the transfer mechanism from point 89 to point 90. The transfer elements have thus been moved back to a starting location and are in position to pick up a preceding mold liner during the die retraction traverse beginning at point 91.

FIGURE 5 illustrates the progressive forming steps involved in the operation of FIGURES 1 and 2. Both longitudinal and transverse sectional diagrams are included in FIGURE 5. The mold liner and its contents are indicated for each of stations A, B, C and E. At station A a loose clay charge is placed in each of the pockets 21a and 21b. The loose charge may occupy approximately one-half the volume of each of the pockets. At station B vibration of the charge liner compacts the charge so that it may occupy less of the total volume of the respective pockets. Vibration and resultant compaction aid in de-airing the body. Vibration may be accomplished at station B by means Well-known in the art as indicated in Ceramic Fabrication Processes by W. D. Kingery, John Wiley & Sons, Inc. (1958) in Section 9, beginning at page 74. At station C the elements 60 and 61 compress the charges so that they occupy much smaller volumes and are compacted as to be substantially free of air within the clay itself. As shown, the dies compact the clay into central mounds. Lip portions extend outwardly from the central mounds to the walls of the liners. At station E the clay, preformed in station C, is forced outwardly and upwardly along the walls of the liner and die to form a relatively thin body of uniform wall thickness.

In FIGURE 6 the preforming die 60 of FIGURE 1 is shown (partially in section) fully inserted into the mold liner 32. The die 60 conforms in its configuration with the inner configuration of the liner 32 except at the bottom. A bottom rim 60a and a dome-shaped recess 60b characterize die 60. The insertion of the die 60 into the mold 32 forces the charge of clay therein into the center of the mold and thus permits subsequent distribution thereof along all four upstanding Walls of the mold trapping only minimal amounts of air therein.

As illustrated in FIGURE 6, the liner 32 intimately nests in the mold. Each mold includes the wall 80 and the casting 81 normally formed in accordance with known practices. The casting material 81 may be aluminum poured around a liner so that the pattern of the mold accurately corresponds with the configuration in uncured state of the desired product.

In the next step shown in FIGURE 7, the entire clay body is forced out into a shell-like form to provide walls of a tank. The mold and the liner correspond with those of FIGURE 6. However, the die 64 is proportioned such that at the bottom of the stroke of the platen 15, the lower end of the die is the same distance from the bottom of the liner 34 as the spacing between the side walls of the liner 34 and the sides of the die 64. All corners such as the corner 340 are rounded on both the liner, the mold and the die so that there will be at all points throughout the body to be formed a uniform thickness.

In a tank mold of the type illustrated in FIGURE 6, dimensions were of the order of 22 inches wide, 12 inches high and 8 inches deep. In order to form such structures with wall thickness of the order of one-half inch, it has been found preferable to pretreat the clay mix by sizing the clay particles. As prepared, the clay is a semi-dry body with water content within the limits of from 12% to 13%. Such a mixture is relatively dry compared to the slips that are employed in the usual methods of casting vitreous ware. Such pretreatment may include production of a slip and then spray-drying the same in spray dryers of the type well-known in the art.

By way of example, a suitable body composition may include the following ingredients in the following proportions:

Percent Kona F-4 feldspar 32.5 Konaflint 1 15.0 Putnam clay 12.5 Monarch clay 12.5 Weldon clay 13.75 Black charm clay 13.75

1 Prepared and sold by International Minerals and Chemical Corporation, Old Orchard Road, Skokie, Ill.

2 Prepared and sold by United Clay Mines Corporation, Trenton, NJ. T 3 Prepared and sold by H. C. Spinks Clay Company, Paris,

The above mixture has the following approximate body chemical analysis:

6 A1 0 22.81 SiO 64.65 F6203 .46 Tto .46 CaO .55 MgO .10 13421 0 2.32 K 0 1.81 Unidentified 6.84

The above mixture has a particle distribution such that 62.82% of the particles are less than 10 microns; 49.15% are less than 5 microns; 36.20% are less than 2 microns; 27.37% are less than 1 micron; 19.62% are less than 0.5 micron; and 9.99% are less than 0.2 micron. The mixture, carefully controlled in size and water content, is introduced into the traveling mold liners as indicated in FIGURE 1.

In order successfully to extract the dies such as dies 64 and 65 from the product without damage thereto, it has been found that two conditions must be established. A lubricant must be present and the temperature of the die must be substantially elevated relative to that of the product. Thus, before each stroke of the platen 15 the die members 6065 are coated, as 'by spraying, with a suitable material which will aid retraction of the die without tearing the thin clay wall from the liner.

A suitable coating material or lubricant for permitting extraction of the die has been found to be an aqueous solution of a material marketed by Oakite Products, Inc., 19 Rector Street, New York, N.Y., as Special Drawing Compound. Such material mixed in proportions of one part to five parts water may be applied to dies 60-65 either by brush or by spray 66 in the manner disclosed in Patent 2,293,070.

In FIGURE 1, heating elements 103 and 101 are provided in the dies 62 and 64, respectively. Heating may be introduced through such electrical heaters or the temperature of the dies may be maintained elevated by other heating means. Similarly, dies 63 and 65 will be provided with suitable heating means so that the temperature of the large die, such as die 64, will be maintained at a temperature of the order of 250 F. The shallow die 65 for forming the lid, having much smaller ar a of contact with the clay body, can be operated successfully at lower temperatures, such as of the order of F.

The foregoing description has dealt with a system in which a semi-dry pulverized clay body is introduced into each liner placed in the system. It will befound satisfactory, however, to carry out the present invention through the use of clay pugs of the type illustrated and described in Patent No. 2,450,437. In that system a clay body is worked into a unified mass from which measured amounts are severed and placed in a mold. In this event, the pug employed will have physical characteristics generally represented by the body composition above de scribed for the pulverized case. The pug will be preformed in the deep liner pocket as by a die 60, following which it will be fully shaped as by a die 64 with the mold liner serving to transport the preformed body from the preform station to the molding station and from there to the extracting station.

Mold liners from station E are delivered to a curing station where the product formed therein is removed and/ or cured. The liner may then be re-used in the system of FIGURE 1. The invention provides substantial advantage over prior art methods in the use of the liner, thus requiring only one, two or three rigid force-opposing molds with relatively resilient liners adapted to nest therein and thus be supported by the rigid molds. The liners, though preferably of a thin-walled metal, may be formed from other materials such as plastics and the like. However, in general, liners will be preferred in which the surface quali'ty can be controlled and wear minimized. In any event, a multiplicity of liners can be provided at substantially lower cost than molds ordinarily found necessary in order to accommodate curing processes. The use of liners with semi-dry clay mixes with high pressure dies permits production of vitreous ware with high efiiciency and desirable finish and minimizes variations in the prod uct. Body materials other than clay may be employed in such system with the same beneficial results.

Having described the invention in connection with certain specific embodiments thereof, it is to be understood that further modifications may now suggest themselves to those skilled in the art and it is intended to cover such modifications as fall within the scope of the appended claims.

What is claimed is:

1. A system for forming deep, thin wall containers of uniform thickness which comprises:

(a) a base,

('b) a platen supported for movement toward and away from said base,

(c) a plurality of rigid fixed molds mounted on said base below said platen, each of said molds having the same inner configuration,

(d) a thin-walled metal-licmold liner having a surface free from joints or openings for nesting in said fixed molds,

(e) dies mounted on said platen and positioned to mate with said fixed molds at spaced stations beneath said platen, a first of said dies having minimal clearance from the side Walls of a mating mold liner and substantial clearance at the bottom thereof, a second die having uniform spacing from both the bottom and the sides of a mating mold liner when said piaten is at the low point of its traverse,

(f) means to insert a charge of semidry granular clay material in said liner, and

(g) means operable in synchronism with retraction of said platen to move each said liner from registration with said first of said dies to registration with said second die progressively to shape said material.

2. A system for forming bodies from semi-dry clay which comprises: a

(a) plurality of like female molds mounted at spaced points in a treating zone, each having an inner surface configuration substantially corresponding with that of the desired body,

(b) thin liners each having unbroken walls and bottom surfaces of configuration corresponding with that of said molds,

(c) means to insert a clay mixture in each said liner entering said treating zone,

(d) a plurality of forming dies having progressively varied shapes located at points along said zone for registration with said molds, and

(e) multi-ton hydraulic ram supporting said dies to apply a ram force to said mixture at each of said points along said zone wherein the force applied at each of said points and the shape of said forming dies force said mixture into the cavity between said liner and the largest of said dies, and.

4. A system for forming deep ceramic containers having relatively thin Walls from semi-dry granular clay charges which comprises:

(a) a base,

(b) a hydraulic ram platen powered for movement with muiti-ton force toward and away from said base,

(c) at least one rigid mold having an open-topped cavity, mounted on said base under said platen having inner walls sloping downwardly and inwardly from said top at angles of but a few degrees,

(d) at least one metallic mold liner having continuous unbroken wall and bottom surfaces and shaped to nest in said mold and adapted to contain said charge,

(e) at least one die mounted on said platen and positioned for mating with said at least one mold, with substantially uniform clearance from the bottom and the side walls of a mating mold liner to mold said charge, and

' (f) means operable in synchronism upon'retraction of said piaten to extract said at least one liner from said at least one mold.

5. The combination set forth in claim 4 and further comprising means to apply lubricant spray to said at least one die, and electrical heating means in said at least one die for maintaining the lubricant film on said at least one die at an elevated temperature.

References Cited OTHER REFERENCES Ceramic Age, p. 68, October 1962.

I. SPENCER OVERHOLSER, Primary Examiner.

D, BALDWIN, Assistant Examiner.

Claims (1)

1. 4. A SYSTEM FOR FORMING DEEP CERAMIC CONTAINERS HAVING RELATIVELY THIN WALLS FROM SEMI-DRY GRANULAR CLAY CHARGES WHICH COMPRISES: (A) A BASE, (B) A HYDRAULIC RAM PLATEN POWEREED FOR MOVEMENT WITH MULTI-TON FORCE TOWARD AND AWAY FROM SAID BASE, (C) AT LEAST ONE RIGID MOLD HAVING AN OPEN-TOPPED CAVITY MOUNTED ON SAID BASE UNDER SAID PLATEN INNER WALLS SLOPING DOWNWARDLY AND INWARLY FROM SAID TOP AT ANGLES OF BUT A FEW DEGREES, (D) AT LEAST ONE METALLIC MOLD LINER HAVING CONTINUOUS UNBROKEN WALL AND BOTTOM SURFACES AND SHAPED TO NEST IN SAID MOLD AND ADAPTED TO CONTAIN SAID CHARGE, (E) AT LEAST ONE DIE MOUNTED ON SAID PLATEN AND POSITIONED FOR MATING WITH SAID AT LEAST ONE MOLD, WITH SUBSTANTIALLY UNIFORM CLEARANCE FROM THE BOTTOM AND THE SIDE WALLS OF A MATING MOLD LINER TO MOLD SAID CHARGE, AND (F) MEANS OPERABLE IN SYNCHRONISM UPON RETRACTION OF SAID PLATEN TO EXTRACT SAID AT LEAST ONE LINEAR FROM SAID AT LEAST ONE MOLD.

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