US3234598A

US3234598A - Apparatus for pressing slurries

Info

Publication number: US3234598A
Application number: US225799A
Authority: US
Inventors: Thomas O Quinn
Original assignee: Indiana General Corp
Current assignee: Indiana General Corp
Priority date: 1962-09-24
Filing date: 1962-09-24
Publication date: 1966-02-15
Anticipated expiration: 1983-02-15

Description

Feb. 15, 1966 T. o. QUINN APPARATUS FOR PRESSING SLURRIES 2 Sheets-Sheet l Filed Sept. 24, 1962 To sL/cT/o/v D/SCHA PGE SLL/FRY FEEDER w R n .0 0 W M t M me D N0 i m E0, M 2,5 2 Mms; 2 6 2 32x22 0 in 34mg 2 2 0 2 $67 22ow91 w k u 2 22 i4 T x ME 7 S 2/ my m 2 2 Z i /O F6 nl oww ETE CNP 9 RER 2 @my 2/ soc ATTORNEYS Feb. 15, 1966A l 1.0.QUINN 3,234,598

APPARATUS FOR PRESSING SLURRIES Filed sept. 24, 1962 2 sheets-sheet 2 E INVENTOR Thomas 0. 00in/7 ATTORNEYS United States Patent O 3,234,598 APPARATUS FOR PRESSING SLURRIES Thomas 0. Quinn, Valparaiso, Ind., assignor to Indiana General Corporation, Valparaiso, Ind., a corporation of Indiana Filed Sept. 24, 1962, Ser. No. 225,799 8 Ciaims. (Cl. 18-16) This invention relates generally to an improved apparatus for pressing slurries and particularly to an improved pressing arrangement for forming a slurry of ferrite material into a desired compact form in the process of forming such ferrite material into permanent magnet units or the like.

In one form of apparatus for pressing slurries a die is provided having a pressing chamber of configuration to form the desired part. The die is open at one end to allow feeding of the slurry into the pressing chamber. After the slurry is in the pressing chamber, the open end of the die is closed by hydraulically moving a filter head against the open end of the die. A die punch is provided in the die for acting on the slurry in the pressure chamber and a hydraulic cylinder actuator external of the die is mechanically linked to the die punch so that by applying pressure to the actuator the die punch is moved toward the filter head to force the fluid in the slurry out of the pressing chamber through the filter head and thus to form a compacted mass which is further treated in the usual manufacturing process.

There are many disadvantages to such an apparatus. For example, the mechanical coupling between the hydraulic cylinder actuator and the die punch must be extremely accurately aligned to operate. Any misalignment affects the nished part or jams the mechanism causing failure thereof. Also the clearance between the punch and the die even though sealed with gaskets permits the fiuid in the slurry due its high hydrostatic pressure to bleed past the seals with resultant ill-effects on the finished part and on the area surrounding the press. A further disadvantage is a limitation placed on the length of stroke permitted for the punch in the die as a result of the mechanical limitations created by the limited stroke of the hydraulic cylinder actuator. Also, since the hydraulic actuator is fixed in size, the pressure supplied to the actuator for driving the punch in the d-ie must be varied with each different die to get the desired pressure on the slurry.

It is, therefore, a principal object of the present invention to overcome the above noted disadvantages and toprovide an improved slurry press.

A further principal object of this invention is to provide an improved wet press wherein the hydrostatic pressure of the iiuid in the slurry is prevented from seeping past the piston by a substantially balanced hydrostatic pressure of the actuating fiuid on the opposite side of the piston.

It is another important object of this invention to simplify the construction of the die and actuating mechanism of a slurry press by eliminating the mechanical hook-up between the driving cylinder and the die punch.

It is a further object of this invention to provide an improved slurry press of a design such that dies having slurry chambers of different configurations may lbe properly actuated with the same fluid pressure.

Another object of this invention is to provide an im- ICC proved slurry press wherein the only limitation on the length of stroke of the die piston is the length of the die itself.

Still another object of this invention is to provide an improved slurry press that is simpler in operation, has

fewer operating parts, is easier to repair and maintain, isv

cheaper to construct, and is more efiicient and therefore more economical to operate.

Other objects, features and advantages of the present invention will be apparent from the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a somewhat diagrammatic elevational view illustrating a slurry pressing arrangement in accordance with the present invention;

FIGURES 2 and 3 are vertical sectional views of the die assembly of FIGURE 1, FIGURE 2 illustrating the position of the die piston prior to the pressing operation and FIGURE 3 illustrating the position of the piston member in ejecting the compacted mass from the die;

FIGURE 4 is a vertical sectional View illustrating a modified press utilizing spring actuated retraction of the die piston member;

FIGURE 4A is a cross sectional view taken along the line 4A-4A in FIGURE 4; and

FIGURE 5 is a vertical sectional view illustrating a,

further modified form of pressing apparatus.

Referring first to the embodiment of FIGURES 1, 2 and 3, there is disclosed a fixed framework 10 having a hydraulic actuator mechanism 11 secured thereto for vertically moving a table 12 on which a die assembly 13 is carried. As indicated diagrammatically in FIGURE 1,

the hydraulic actuator 11 may have a cylindrical cham-i ber 15 with a piston member 16 movable therein which is linked by means of a piston rod 17 to the support table 12. To raise the table 12 hydraulic pressure is applied to the hydraulic line 19 connecting with the lower chamber of actuator 11 while fiuid is drained from the upper chamber of the cylinder via hydraulic line 20. Hydraulic pressure may be applied to the line 20 communicating with the upper chamber of the cylinder 11 to return the table 12 to its lower position shown in FIGURE l.

As best seen in FIGURE 2, the die assembly 13 includes a die casing generally designated by the reference numeral 22 which has interior surfaces such as

cylindrical surfaces

23 and 24 defining an elongated `interior space within the casing. The casing is also provided with an open upper end as indicated at 25 which provides access to a presing chamber 27 within the casing. The pressing chamber 27 will have a cross sectional configuration corresponding to the cross sectional configuration to be formed by the press. For example, where an annular or ring shaped configuration is to be formed a core member indicated generally at 29 extends axially of the casing and is provided with an exterior cylindrical surface 30 defining a boundary of the pressing chamber 27.

As illustrated in FIGURE l, the slurry t-o be compacted such as barium ferrite slurry utilized in forming permanent magnets of the ceramic type, may be supplied to the pressing chamber 27 Via the open end 25 of the die casing 22 by means of a suitable conduit 32 from a slurry feeder 33 which may take the form disclosed in U.S. Patent No. 2,877,929 issued March 17, 1959.

When the slurry has been fed into the pressing chamber 27, the conduit 32 is removed, and the hydraulic actuator 11 is supplied with pressure from the hydraulic pressure control unit indicated at 35 in FIGURE 1 to raise the die assembly 13 and press the open end 25 of the die casing 22 against a filter head assembly generally designated by the reference numeral 37. The filter head assembly may include a suitable filter paper 38 and a filter block 39 having suitable drainage openings such as indicated at 40 aligned with the pressing chamber 27 and leading to a discharge passage 42 which may be connected to a suitable suction device for removing fluid from the collection chamber 43. The filter paper 38 may be held in the position shown in FIGURE 1 by any suitable means or may be placed on the end 25 of casing 22 after conduit 32 is displaced therefrom. The filter head assembly is fixedly secured to the frame so as to be rigidly fixed relative to the cylinder 11; The hydraulic pressure control means'35 may supply fluid under pressure to the hydraulic line 19 continuously during the slurry pressing Aoperation so as to insure sealing of the open end Vof the die casing 22 against the filter head assembly 37.

Also during the pressing operation, direct current may Ibe supplied from source 44 to a helical winding indicated at 45 by means of a switch 46 to produce a vertically directed magnetic orienting field in the pressing chamber '27.

In FIGURE 2 the barium ferrite `slurry (not shown) is sealed in the pressing chamber 27 `by means of the filter paper 38 and filter block 39 in conjunction with the pressure applied by the ta'ble 12 at the lower end of the die assembly. The hydraulic pressure control of FIG- URE 1 includes a hydraulic pressure source 47 which may supply hydraulic-fluid under pressure to both

lines

48 and 49 indicated in FIGURES 1 and 2 to initiate .a pressing operation. As seen in FIGURE 2, a hydraulic fluid applied to the line 48 enters an actuating chamber 50 `by means of an inlet port 51 in casing member 52 of casing 22 and fluid pressure supplied to line 49 is applied to an actuating chamber S4 through an inlet port 55 of casing member 52. An actuating piston 55 forms a uni-tary part of the die plunger assembly within the die casing 22 and as seen in FIGURE 2 has a greater cross sectional area exposed to the lower 4actuating chamber S4 than t0 `the upper actuating chamber 50. Thus with equal pressures in the two chambers, there is a net upward force on the plunger assembly 60 tending to compress the slurry in the pressure chamber 27. The lower end of the die casing 22 is closed by means of a suitable base member 62 `secured lto the casing member 52 by means of screws such as indicated at 64. The surface 65 of the base 62 which engages the lower surface of the actuating piston 55 may be grooved as indicated at 66 to provide fluid communication Ibetween the actuating chamber portion 54 and actuating chamber portions 68 and 69. The fluid actuating pressure is thus communicated to the region at the lower side of the pressing piston 72 which is a unitary part of the plunger assembly 60. The pressure at the region 70 substantially corresponds to the hydrostatic pressure of the slurry in the pressing chamber 27 during the pressing operation so as to tend to prevent leakage between the pressing piston member 72 and the surface 30 of the core 29.

The actuating chamber 50 communicates with a region 75 immediately adjacent the outer perimeter of the pressing piston member 72 lby means of passages 77 in an adjustable stop member of ring configuration. The lower surface 81 of the stop member 80 abuts the upper surface of actua-ting piston member 55 as indicated in FIG'URE 3 at the end of the stroke of the die plunger assembly 60. Since the pressure in the chamber 50 is the same as the pressure in the chamber 54, the pressure in the region 75 adjacent the outer perimeter of the pressing piston member 72 is comparable to the hydrostatic pressure of the yslurry within the pressing chamber 27 to tend to prevent leakage between the pressing piston member 72 and the internal surface 23 of thedie casing 22.

With a given pressure applied to the actuating chambers 50 and S4, the upper surface 85 of piston member 72 will be driven to a position as indicated by the dash line 85a in FIGURE 3 with the die assembly 13 pressing against the filter head 37 under the impetus of the hydraulic actuator 11. When, however, uid pressure is remove-d from the line 19 of the actuator 11 and the table 12 is retracted to a position such as indicated in FIGURE 1, the fluid pressure in the chamber 54 will drive the actuating piston member 5S against the stop surface 81 which will move the upper surface 85 of pressing piston member 72 to the position shown in solid outline in FIG- URE 3 ejecting the compacted mass 90 of ferrite material which is indicated in FIGURE 3. The hydraulic pressure may be removed from actuating

chambers

50 and 54 before table 12 is retracted, so that piston member 72 remains substantially at the pressing position 85a during lowering of table 12. This avoids exerting substantial forces on the mass during the ejection step when the mass is not completely laterally supported by

surfaces

23 and 30.

With this mode of operation, when the table has been lowered to the position shown in FIGURE 1, pressure is reapplied to

chambers

50 and 54 to move the piston member 72 from the pressing position indicated at 85a to the ejecting position shown in solid outline in FIGURE 3. The mass 90 will have a ring shape in conformity with the cross section of the pressing chamber 27 and will have a thickness corresponding to the spacing between the dash line 85a and the upper surface 91 of casing 22. The mass 90 may be removed by sliding it laterally over the surface 91 and onto a suitable receiving surface which is flush with surface 91 at the time the mass 90 is removed from the die. This operation may be carried out by a suitable mechanical device where the pressing procedure is carried out automatically. When it is desired to retract the die plunger assembly 60 to -the initial position shown in FIGURE 2, the hydraulic valve member 94 is turned through 120 in the clockwise direction as seen in FIGURES 2 and 3 to connect the line 49 to drain while pressure from the source 47 is still 'being supplied via line 48 to the chamber 50.

For convenience of manufacture and assembly, the various major components which have been referred to r are preferably formed of a number of individual parts which will now be briefiy referred to by way of example and not of limitation.

The die casing 22 includes an upper tubular member 180 having a tubular lining 101 providing the interior surface 23. The casing 22 further includes a cover part 194 which is secured to the part 100 by means of screws and is secured to the lower member 52 of the casing by means of screws 107. Suitable seals are provided between the various parts of the casing 22 to provide a iiuid tight interior space. The stop member 80 which is considered as part of the casing 22 is threadedly engaged with the cover member 104 so as to be axially adjustable for adjusting the upper limit of travel of the plunger assembly 6i). The surface 85 is substantially flush with surface 91 and preferably slightly thereabove in the ejection position of the plunger assembly shown in FIG- URE 3.

The core assembly 29 includes an upper cylindrical rod having a tubular liner 111 providing the exterior surface 30. The rod 11) has a threaded portion 114- secured therewith and threadedly engaged with a lower core member of cylindrical configuration. The lower member 115 is secured in a recess in base 62 by means of screws 117. Suitable sealing means are provided b'e'tween casing members 52 and the base 62 and between the base 62 and the lower core member 115 to prevent leakage from the actuating chamber 54.

The plunger assembly 60 includes a lower tubular member threadedly secured to the pressing piston member 72 at its upper end and threadedly secured to the actuating piston member 55 at its lower end.

Gaskets are indicated at 120 and 121 between the outer perimeter of the pressing piston member 72 and the die surface 23 and further gaskets are indicated at 122 and 123 between the inner perimeter of the pressing member 72 and the die assembly surface 3l] for preventing the slurry from escaping back into the

actuating chambers

50 and 54 and to prevent the hydraulic fluid in the actuating chambers from eroding the corners of the compressed material in the pressing chamber 27. During normal pressing of the slurry, the difference in the hydrostatic pressure of the slurry and the hydrostatic pressure of the hydraulic fluid in the

actuating chambers

50 and 54 is relatively low so that no leakage past the gaskets will occur. The only time the seals are really necessary is when the piston member 72 is in the fully advanced position indicated by the dash line 85a in FIG- URE 3 and before the pressed material 90 is removed from the die. The gaskets 120-123 may comprise rings having a cross section with four lobes which lobes are seated in the respective four corners of the recesses in the pressing piston member 72. An additional sealing ring is indicated at 125 at the outer perimeter of the actuating piston member 55 which travels on the die surface 24. It will be observed that the plunger assembly 60 is entirely confined within the interior space of the die casing 22 so as to form what will be termed a free or floating type piston. Such a piston is in contrast with the type wherein the die plunger has a stem extending through the end wall of the die which stem is coupled to a hydraulic actuator at the exterior of the die assembly. In such a case the die plunger is provided with a force transmitting actuating stern extending to the exterior of the die casing and would not constitute a free or floating type of piston arrangement.

Where a magnetic orienting eld is applied vertically in the pressing chamber 27, certain of the parts should be of non-magnetic material while others may be or preferably are of magnetic material. A suitable choice of materials is indicated in the following table:

Practical hydraulic circuits would of course include means for preventing the formation of air pockets in the actuating chambers during flow of hydraulic fluid therefrom, and the term drain is used herein as including such an air exclusion means.

Summary of operation for the embodiment of FIGURES 1-3 In the embodiment of FIGURES 1 through 3, a slurry of barium ferrite material or the like is first fed to the pressing chamber 27, FIGURE 2, from a slurry feeder 33, FIGURE l, via a conduit 32. The conduit 32 is then removed and hydraulic pressure applied to the hydraulic line 19 to raise the table 12 together with the die assembly 13 until the open end 25 of the die casing 22 is pressed against the filter head 37, FIGURE 1. The hydraulic pressure source such as indicated at 47 in FIG- URE 2 is then activated as by opening a shut-olf valve 126 to supply the same hydraulic actuating pressure via

lines

48 and 49 to the

actuating chambers

50 and 54 of the die casing 22. The difference in area of the plunger assembly 60 exposed to the respective actuating chambers 51) and 54 results in driving of the plunger assembly 60 in the upward direction and preferably compressing the slurry in the pressing chamber 27 with a pressure substantially equal to the actuating pressure. Water from the slurry is forced through the lilter paper 38 and through the passages 40 in the filter block 39 to a suitable discharge or drain means. The value of pressure supplied to the actuating chambers may be the same regardless of the cross sectional configuration of the part to be formed since the difference in the effective plunger areas exposed to

chambers

50 and 54 may always be equal to the cross sectional area of the pressing chamber 27 regardless of its cross sectional conliguration.

The pressure supplied to the

actuating chambers

50 and 54 is such as to move the pressing piston member 72 `from the position shown in FIGURE 2 Vto the pos-ition indicated yby the dash line a in FIGURE 3. This movement of the piston member 72 results in the formation of a compact mass as indicated at of barium ferrite material. The mass 90 may be ejected from the die by removing actuating pressure from

chambers

50 and 54 as by closing valve 126, FIGURE 3, and lthen supplying hydraulic pre-ssure to the line 20 shown in FIGURE 1 While connecting line 19 to drain to lower the .table 12 to the retracted position shown in FIGURE l. Thereafter valve `126, FIGURE 3, is again opened t-o supply the actuating pressure to

chambers

50 and 54 so as to move the plunger assembly 60 from the pressing position Iindicated by dash line 85a to the ejecting position shown in solid outline in FIGURE 3 with the lower surface of the compacted mass 90 substantially ush with the die upper surface 91, and preferably slightly .thereabove To retract the plunger assembly 60 to the position shown in FIGURE 2, valve 94, FIGURES 2 and 3, may be turned in .the clocklwise direction to connect the -lolwer actuating chamber 54 to drain While the upper chamber 50 still receives fluid pressure from the source 47.

It will be apparent that multiple pressing chambers may lbe formed in a single die casing and that independently movable pressing piston members may lbe movable in the respective pressing chambers to form multiple parts in the same die casing. The pressing piston members may utilize the same actuating chamber or chambers. FIG- URES 2 and 3 may be considered as illustrating such a modification by considering that the pressing chamber 27 is divided into semi-circular chambers and -by considere ing that the plunger assembly 60 -is divided into two separate independently movable half sections each individually actuated by the actuating

chambers

50 and 54 in which the two half sections `are movable. By this means the two plunger sections would be advanced at their oiwn rate to compress the material in the respective pressing chamber sections and such an arrangement would allow for differences in the pressing rates `of the slurries in the two pressing chamber sections.

Where a multi-piston external hydraulic actuator is utilized for actuating a plurality of plunger mechanisms, if uneven amounts of -slurry are fed into the respective die lcavities the balance of the actuator is upset and improperly pressed parts result. By utilizing separate free floating plun-ger assemblies in a common die casing as just described, each plunger section may advance at its own rate without affecting the advance of the other plunger section.

It will be yobserved that the pressure supplied to the

actuating chambers

50 and 54 determines the pressure applied to the slurry; that is, the pressure exerted by the piston member 72 on the slurry is substantially identical to the pressure supplied by the pressure source 47 to the

actuating chambers

50 and 54. With a multiple cavity die, the pressure applied to each cavity would be identical to the actuating pressure and would be selected to give the proper cha-racteristics of the. resultant compacted mass such as indicated at 90 in FIGURE 3. The same hydraulic pressure source supplying the proper pressing pressure would then be applicable to dies of any desired configuration so long as the required pressing pressure on the slurry lwere the same. In other words, the pressing chamber 27 may have any desired cross sectional coniiguration in the embodiment of FIGURES 2 and 3 without changing the pressure required from the. hydraulic pressure source 47.

Description of the embodiment of FIGURE 4 FIGURE 4 illustrates a modified pressing assembly utilizing only a single actuating chamber 140 and returning the pressing piston member 141 to its initial position by means of a compression spring '143. The pressing assembly comprises a die casing 145 having an interior space extending Ifor the length of the die assembly and defined by interior surface port-

ions

147, 148, 149 and 150. The die casing is formed by an upper member 150 having a tubular liner 151 and a tubular liner 152 prolviding the interior surface 147. The upper casing member 150 is secured to an intermediate member i154 by means of screws 155, the member `154 providing the interior surface portions 148 and 149. A lower tube member 156 is secured to the lower end of the intermediate member 154 by means of screws 157, and the end wall |159 of member '156 rests on the table 12 for pressing of the open upper end -160 of the casing against the filter head generally designated by the reference numeral 37 and illustrated in greater detail in FIGURE l. The die casing may also be considered as including a plate 1263 which is of disk coniiguration and is clamped between the members 150 and 154 by the screws 155. The. plate y163 mounts a central core member 165 which is secured centrally of the plate 163 by means of a screw 167. The plate 163 has a pair of arcuate slots 168 and 1619 as shown in FIGURE 4A which receive the bi-furcated end portion 170 of the pressing piston lmember 1411. The radial dimension of the. slots E163 and 169 may be substantially Igreater than the radial dimension of the end portion 170 of member 141 t-o provide uid communication through the slots to the region adjacent a peripheral shoulder portion .171 of lower surface portion 172 of the piston member 141. The peripheral shoulder 171 has an inner circular margin of diameter equal to the outside diameter of end portion `170 and has an outer circular edge indicated at 1710i in FIGURE 4A equal to the outside diameter of piston member 141. As the piston member 141 moves upwardly the inner surface of fliner l152 and then of liner 151 is progressively exposed to the pressure of chamber 140 at the space Ibelow the entire perimeter of shoulder portion 17:1 of the piston member 141. The piston member 141 `is illustrated as being provided with sealing rings which may be of the same type as described in connection with FIGURES 2 and 3.

A bolt 175 may be secured to the lower end 170 of the piston member 141 by means of a cup member 176 threaded onto end |170. A threaded collar member i178 is threaded onto the lower end. of the bolt 175 and locked thereon by means of a nut 179 to serve as an abutment for engagement with the compression spring 143 which is thus effective to urge the piston member 141 downwardly toward the initial posi-tion illustrated in FIGURE 4. A washer l182 may be interposed between the cup member 176 and a seating surface 183 of intermediate member 154, and suitable means may be -provided for insuring fluid communication at all times between the actuating chamber `140 and the spring chamber 185; for example, the surface 183 :may be grooved as indicated at 187. The surface 1172 including shoulder portion 1171 at the lower side of piston member 141 may actually be spaced slightly above the upper surface of plate 163 when cup 176 and washer 182 are bottomed against seating surface 183.

The exterior surface 190 of core member 165 together with the interior surface 147 of the liner 151 and the upper surface 192 of piston member 141 defines a pressing chamber 194 receiving a barium ferrite slurry 195 which is to be compressed `as in the preceding embodiment. There is fluid pressure communication between the actuating chamber 140 and the lower surface portion 197 of piston member 141 through the arcuate slots 1,68 and 169 so that there is fluid in the region 198 at the same pressure as in the actuating chamber 140.

As diagrammatically indicated in FIGURE 4, hydraulic pressure from a pressure source 201 is supplied via line 202 and an inlet passage 203 in member 154 to the actuating chamber 140 to apply actuating pressure to the piston member 141 at its

lower surface portions

172 and 197 sorthat the piston member 141 applies a pressure to t-he pressing chamber 194 which is substantially identical to the pressure supplied to the actuating chamber 140 from the source 201 as in the previous embodiment. The piston member 141 is actually of the free floating type as in the previous embodiment since the bolt 175 does not transmit actuating force during the working stroke of the piston but is simply a device for returning the piston to its initial position. It will be observed that the maximum distance through which the pressing piston 141 may be moved is slightly greater than the maximum length of the pressing chamber 194, so that the compacted mass of barium ferrite (corresponding to that indicated at 90 in FIGURE 3) may be ejected from the pressing chamber after the upward hydraulic force is removed from the table 12 and the open end 160 of the casing 145 is retracted from the filter head 37. With the filter head 37 closing the open end 160 of the casing, and pressure supplied to the line 202, the piston member 141 will compress the slurry 195 to a predetermined thickness `substantially less than the length of the pressing chamber 194 and will stop at a pressing position corresponding to that illustrated in FIGURE 3 by the dash line a.

After `the compacted mass has been ejected in the same manner as illustrated in FIGURE 3, the piston member 141 is returned to the initial position shown in FIGURE 4 by rotating valve 210 through an `angle of in the clockwise direction to connect the line 202 to drain and allow the compression spring 143 to ret-urn the piston member 141.

In the embodiment of FIGURE 4, the actuating pressure o-f chamber is communicated to the

surfaces

171 and 197 at the outer and inner perimeters of the piston member 141 so as to tend to equalize the pressures at the leading and trailing sides of the piston member 141 completely about the inner and -outer perime-ters of the piston member during the pressing operation. Thus, during normal pressing of the slurry, the difference in the hydrostatic pressure of the slurry 195 and the hydrostatic pressure of the hydraulic fluid in the actuating chamber 140 is relatively low so that no leakage occurs past the gaskets such as indicated at 211-214. The only time the gaskets are really necessary is when the piston is in the fully advance-d position corresponding -to the position 85a in FIGURE 3 and before the pressed mass of barium ferrite or the like is removed from the die.

Where a vert-ical orienting field is applied to pressing chamber 194 by means of the winding 45 shown in FIGURE 1, the magnetic character of the material used 9 for the various p-arts shown in FIGURE 4 may be as follows:

Summary of operation of the embodiment of FIGURE 4 In FIGURE 4, the slurry 195 is supplied to the pressing chamber 19'4 -by means of the conduit 32 from the slurry feeder 33 exactly as indicated in IFIGURE 1. -FIGURE 4 indicates the case where filter paper 38 isplaced on the casing 145 after the slurry is supplied to the pressing chamber, but suitable means may be provided for holding the filter paper against the lower end of the filter block 39 as in FIGURE 1, if desired. Thereafter, table 12 is actuated to press the open end 160 of the casing 145 again-st the filter head assembly 37 as in the preceding embodiment. Hydraulic pressure source 201 then supplies hydraulic fluid at a predetermined pressure to the

chambers

140, 185 and 198 to move the piston member 141 upwardly against the action of the com-pression spring 143. The pressure exerted by the piston member 141 on the slurry 195 is substantially identical to the pressure supplied to the actuating chamber 140. The pressure exerted on the pressing chamber 194 is, however, somewhat less than the pressure supplied to the actuating chamber 140 because of the action of the compression spring 143. The force exerted -by the spring 143 can, however, be relatively small since its only function is to return the piston 141 to its initial position after the valve 210 has connected the actuating chamber 140 to drain.

When the slurry 195 has been formed into a compact mass in the same way as illustrated in connection with FIGURE 3, valve 210 may be turned through 60 to shut-off the supply of uid pressure to the actuating chamber 140. Thereafter rthe table 12 is retracted and valve 210 returned to the position shown in FIGURE 4 so that actuating pressure in chamber 140 will cause the piston member 141 to eject the compacted mass from the pressure chamber 194. The stroke of the piston member 141 is such that the upper surface thereof 192 reaches a level substantially flush with and preferably slightly above the open end 160 in t-he same way -as explained in connection with FIGURE 3 `for the previous emb-odiment.

To return the piston member 141 to its initial position illustrated in FIGURE 4, valve 210 is turned through 120 in the clockwise direction whereupon spring member 143 returns the piston member 141 to the position shown in FIGURE 4.

It will be apparent that a multiple cavity die in accordance with the principles of FIGURE 4 may be constructed wherein the pressing pistons for the respective pressing chambers operate independently of each other but receive the same actuating pressure. Individual spring return means can be utilized with each individually acting piston member, for example.

Descrip-tion of the embodiment of FIGURE 5 In the embodiment of FIGURE 5, the hydraulic actuator 11 of FIGURE 1 is omitted and in its place a retainer member 220 is threadedly engaged with the open end 221 of the die casing 222 so as to clamp the filter head assembly 224 in closingrelation to the pressing chamber indi- 10 cated at 226. The retainer member 220 is provided with oppositely projecting

arms

229 and 230 which are convienently grasped manually in threading the retaining member 220 onto the end of the die casing 222.

The Iilter head assembly 224 has been illustrated as including a filter ring 232 having suitable passages therein such as indicated at 233 in alignment with `the pressing chamber 226. A suitable filter paper of corresponding ring configuration is indicated at 235 which is retained in closing relation to the open end of the die casing 222 by means of the filter ring 232 and retaining member 220.

The casing 222 is shown as being made up of parts 240 and 241 threadedly engaged as indicated at 242. The die assembly further comprises a central core 245 including

core members

246 and 247 secured together by means of a screw 248 and secured to the closed end 250 of casing member 241 by means of a screw 252. The

core members

246 and 247 are provided with cylindrical holes which are in alignment with cylindrical holes in the base 250 of the casing member 241. A water-cooled electrical conductor 257 has straight length portions 25761 and 257b extending in the aligned holes and joined in space 222a by a curved length portion 257C. The conductor 257 may be connected with a direct current source 258 by means of a switch 259 for setting up an orienting magnetic field in pressing chamber 226 during the pressing operation.

The interior surface 270 of the die casing 222 and the interior surface 271 of the central core assembly serve .to define the annular pressing chamber 226 which receives a barium ferrite slurry (not shown) as in the preceding embodiments. Sealing rings are indicated at 276 and 277 for sealing off the pressing chamber 226. A piston member 280 is indicated at its initial position and may be provided with sealing rings 281-284 as in the preceding embodiments. An actuating chamber is indicated at 290 which is in fluid communication with hydraulic pressure source 291 via line 292, valve 293, line 294 and inlet opening 295 in casing member 241. The actuating chamber 290 communicates with the lower end of the piston member 280 by means of an annular clearance space 297 so that actuating fluid pressure is applied at the rear or lower side of the piston member 280 at both the inner and outer perimeter thereof. As the piston member 280 is driven upwardly in the pressing chamber 226, water is driven through the filter paper 235 and through the passages such as 233 to a collection chamber 302 from which water is withdrawn by means of a passage 303 in the retainer member 220. The passage 303 may lead to a downwardly extending hose so that water is removed from the filter head at the end of the pressing operation by means of a siphoning action. A similar arrangement may be used in FIGURE 1 for removing water which is not forced from the filter head by the hydrostatic pressure during the pressing operation.

After the slurry material has been compacted into the desired configuration, the valve 293 may be turned through 60 to shut off the supply of hydraulic pressure to the actuating chamber 290. Thereafter the

handles

229 and 230 may be manually operated to rotate the retaining member 220 in the direction to unscrew the same from the top end of the casing 222. The valve 293 is then returned to the position shown in FIGURE 5 to connect the source 291 to the actuating chamber 290. The actuating pressure is then sufficient to drive the cornpacted mass out of the pressing chamber 226 in the same manner as illustrated in FIGURE 3. When the piston member 280 is driven to a position with its upper surface substantially liush with the surface of end 221 of the casing 222, the valve 293 is actuated to shut off pressure to the actuating chamber. Thereafter, the compacted mass of barium ferrite may be removed as by sliding it laterally over the surface of end 221 of the casing and onto a supporting surface substantially flush therewith. The piston member 280 may be returned to its initial position Part Character of Name of Part Reference Material Num eral Retaining member 220 Non-magnetic. Filter ring 232 Do. Upper casing part.- 240 Magnetic. Lower easing part 241 Do. Upper core member 246 Do. Lower core member 247 Do. Piston member 280 N on-magnetic.

Summary of operation of the embodiment of FIGURE In the embodiment of FIGURE 5, the barium ferrite slurry is supplied to the pressing chamber 226 by removing the retaining member 220 manually together with the filter head assembly 224. After lling of the pressing chamber 226 with the barium ferrite slurry, the filter head 224 is reapplied and the retaining member 220 threaded onto the upper end of the die casing 222 to clamp the filter head in position. Orienting current may be supplied to conductor 257 by closing switch 259. Hydraulic pressure from source 291 is then supplied to the actuating chamber 290 which transmits pressure to the lower side of the pressing piston member 280 to drive the piston member 280 in the upward direction. The piston member 280 is of the lfree or floating type as in the preceding embodiments with the actuating fluid pressure acting directly at one side thereof and the opposite side thereof (the upper side) acting on the slurry. When the piston member 280 has reached its final position a predetermined distance below the filter head 224, the hydraulic pressure may be shut off by turning valve 293 through 60, for example. The `retaining member 220 then may be manually unthreaded from the die casing 222 and the hydraulic pressure reapplied to the actuating chamber 29@ to drive the compacted mass of barium ferrite out of the pressing chamber 226. When the compacted mass has been suitably ejected, valve 293 is turned to an off position until the mass has been removed. Thereafter, valve 293 is positioned 120 counterclockwise from the position shown in 'FIGURE 5 to connect the actuating chamber 290 to drain. The piston member 280 may be returned to its initial position manually, for example by means of a suitable tool inserted into the pressing chamber 226.

As in the previous embodiments, the pressing chamber and piston member 280 may be considered as being split into two separate sections to form two separate compacted masses so as to constitute an illustration of a multiple cavity die having a com-mon actuating chamber receiving a common actuating pressure.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of the present invention.

I claim as my invention:

1. A slurry pressing devi-ce comprising a die assembly having cavity defining means providing an elongated die cavity of a cross sectional contour corresponding to the cross sectional contour of a mass to be for-med,

a filter head assembly for closing said cavity at one end thereof,

a free floating plunger assembly having pressing means of cross sectional contour movably fitting in said cavity of said die assembly and having one side thereof defining a movable boundary of a slurry pressing cha-mber of said cavity and said plunger assembly being movable toward said one end of said cavity to compress a slurry in said pressing chamber and drive fluid `from the pressing chamber through said filter head assembly,

means providing for loading of a slurry into said pressing chamber,

said die assembly having actuating chamber defining means rigidly connected with said cavity defining means and providing an actuating chamber within said die assembly for containing fluid under pressure acting on said plunger assembly to drive said plunger assembly toward said filter head assembly, and

means providing for delivery of fluid under predetermined pressure to said actuating chamber to compress the slurry in said pressing chamber to a predetermined configuration,

said actuating chamber defining means providing a second actuating chamber within said die assembly for containing uid under pressure acting on said -plunger assembly to drive said plunger assembly away from said filter head assembly, the area of said plunger assembly exposed to uid pressure in said second actuating chamber being substantially less than the area of said plunger assembly exposed to fluid pressure in the first-mentioned actuating chamber, and said delivery means delivering iiuid -under said predetermined pressure to both said first mentioned and said second actuating chambers during pressing of the slurry in said pressing chamber.

2. The device of claim 1 with the difference between the area of -said plunger assembly exposed to said fluid pressure in said first mentioned and said second actuating chambers being substantially equal to the cross sectional area of said pressing chamber.

`3. The device of claim 1 with said. pressing means having an opposite side opposite said one side thereof, said die assembly including a core member extending centrally of said `die cavity, said pressing means being in slidable relation to the exterior surface of said core member, and means providing uid communication between the first mentioned actuating chamber and said opposite side of said pressing means at the inner perimeter thereof, and means yproviding fiuid communication between the second actuating chamber and said opposite side of said pressing means at the outer perimeter thereof.

4. A slurry pressing device comprising a die assembly having cavity defining means providing an elongated die cavity of a cross sectional contour corresponding to the cross sectional contour -of a mass to be formed,

a filter head assembly for closing said cavity at one end thereof,

a free floating -plunger assembly having pressing means of cross sectional contour movably fitting in said cavity of said die assembly and having one side thereof defining a movable boundary of a slurry pressing chamber of said cavity and said plunger assembly being movable toward said one end of said cavity to compress a slurry in said pressing chamber vand drive fluid from the pressing chamber through said filter head assembly,

means providing for loading of a slurry into said pressing chamber,

said die assembly having actuating chamber defining means rigidly connected with said cavity defining means and providing an actuating chamber within said die assembly for containing fluid under pressure acting on said yplunger assembly to drive said plunger assembly toward said filter head assembly, and

means providing for delivery of fiuid under predetermined pressure to said actuating chamber to compress the slurry in said pressing chamber to a predetermined configuration,

said die assembly having a core member extending centrally of said die cavity, and electrical conductor means extending in said core member for the length of said pressing chamber and closely adjacent thereto for producing a magnetic orienting field in said pressing chamber.

5. The device of claim 4 with said cavity defining means and said core member being of magnetic material, and said electrical conductor means providing for current flow in one direction at one diametric side of said core member and providing for current flow in an opposite direction at an opposite diametric side of said core member.

6. A slurry pressing device comprising a die means having an open end and la closed end wall forming an elongated die cavity therebetween,

a core member mounted within said die cavity,

a filter head assembly for closing the open end of said cavity,

a free fioating plunger assembly mounted within said die cavity and slidably mounted on said core member,

said free lioating plunger assembly comprising a pressing piston means, an actuating piston means, and a connecting means interconnecting said pressing and actuating piston means,

said pressing piston being in slidable contact with said core member and cavity walls,

one end of said pressing piston defining a movable boundary of a slurry pressing chamber formed between said pressing piston and said filter assembly when said filter assembly closes the cavity open end,

said connecting means being connected to the other end of said pressing piston and spaced from the inner and outer side walls of said other end to form inner and outer .pressing piston perimeter-s,

first and second actuation chambers fonmed between said pressing piston and said cavity closed end wall,

means communicating the actuation chambers with the pressing piston inner and outer perimeters with one of said actuation chambers being in communication with one end of the actuation piston and the other actuation chamber being in communication with the other end of the actuation piston, and

means providing for delivery of fluid under predetermined pressure to said first and second actuating chambers to move said pressing piston toward the filter assembly to compress a slurry in said pressing chamber to a predetermined configuration.

7. A slurry pressing device comprising a die means having an open end and a closed end wall forming an elongated die cavity therebetween,

a core member mounted within said die cavity,

a lter head assembly for closing the open end of said cavity,

said free fioating plunger assembly comprising a pressing piston means, an actuating piston means, and a connecting means interconnecting said pressing and actuating piston means, said pressing piston being in slidable contact with said core member and cavity walls,

said connecting means being connected to the other end of said pressing piston and spaced from the inner and outer side walls of said other end to form inner and outer pressing piston perimeters,

a first actuation chamber formed between one end of said actuation piston, the cavity walls and said pressing piston means,

means communicating the first actuation chamber with the pressing piston outer perimeter,

a second actuation chamber for-med between the other end of actuation piston means and said cavity walls,

means communicating the second actuation chamber with the pressing piston inner perimeter,

8. A slur-ry pressing device comprising a die means having an open end and a closed end wall forming an elongated die cavity therebetween,

a core member centrally mounted within said die cavity,

a filter head assembly for closing the open end of said cavity,

a free oating plunger assembly mounted within said die cavity and slidably mounted on said core member,

said free floating plunger assembly comprising a pressing piston means, an actuating piston means, and a connecting means interconnecting said pressing and actuating piston means,

said connecting means being connected to the other end of said pressing piston spaced from the inner and outer side walls of said other end to form inner and outer pressing piston perimeters,

said connecting means being spaced outwardly from the core member and inwardly from the cavity walls below said pressing piston,

said actuating piston being in slidable contact with said cavity wall and spaced from said core member,

a first actuation chamber formed between said actuation piston, the cavity walls and said connecting means,

means communicating the first actuation chamber with the pressing :piston outer perimeter,

a second actuation chamber formed between the other end of said actuation lpiston and said closed cavity end,

means communicating the second actuation chamber with the pressing piston inner perimeter, and

means providing for delivery of fiuid under predetermined -pressure to said first and second actuating chambers to move said pressing piston toward the filter assembly to compress a slurry in said pressing chamber to a predetermined configuration.

References Cited by the Examiner UNITED STATES PATENTS (Other references on following page) UNITED 1 5 STATES PATENTS Haller 18-16 XR Zink et a1 18-5 Schwable 18-5 Hunsdecker.

Haes etal.

16 FOREIGN PATENTS 35 2,433 1931 Great Britain.

I. SPENCER OVERHOLSER, Primary Examiner.

MICHAEL V. BRINDISI, Examiner.

Claims

1. A SLURRY PRESSING DEVICE COMPRISING A DIE ASSEMBLY HAVING CAVITY DEFINING MEANS PROVIDING AN ELONGATED DIE CAVITY OF A CROSS SECTIONAL CONTOUR CORRESPONDING TO THE CROSS SECTIONAL CONTOUR OF A MASS TO BE FORMED, A FILTER HEAD ASSEMBLY FOR CLOSING SAID CAVITY AT ONE END THEREOF, A FREE FLOATING PLUNGER ASSEMBLY HAVING PRESSING MEANS OF CROSS SECTIONAL CONTOUR MOVABLY FITTING IN SAID CAVITY OF SAID DIE ASSEMBLY AND HAVING ONE SIDE THEREOF DEFINING A MOVABLE BOUNDARY OF A SLURRY PRESSING CHAMBER OF SAID CAVITY AND SAID PLUNGER ASSEMBLY BEING MOVABLE TOWARD SAID ONE END OF SAID CAVITY TO COMPRESS A SLURRY IN SAID PRESSING CHAMBER AND DRIVE FLUID FROM THE PRESSING CHAMBER THROUGH SAID FILTER HEAD ASSEMBLY, MEANS PROVIDING FOR LOADING OF A SLURRY INTO SAID PRESSING CHAMBER, SAID DIE ASSEMBLY HAVING ACTUATING CHAMBER DEFINING MEANS RIGIDLY CONNECTED WITH SAID CAVITY DEFINING MEANS AND PROVIDING AN ACTUATING CHAMBER WITHIN SAID DIE ASSEMBLY FOR CONTAINING FLUID UNDER PRESSURE ACTING ON SAID PLUNGER ASSEMBLY TO DRIVE SAID PLUNGER ASSEMBLY TOWARD SAID FILTER HEAD ASSEMBLY, AND MEANS PROVIDING FOR DELIVERY OF FLUID UNDER PREDETERMINED PRESSURE TO SAID ACTUATING CHAMBER TO COMPRESS THE SLURRY IN SAID PRESSING CHAMBER TO A PREDETERMINED CONFIGURATION, SAID ACTUATING CHAMBER DEFINING MEANS PROVIDING A SECOND ACTUATING CHAMBER WITHIN SAID DIE ASSEMBLY FOR CONTAINING FLUID UNDER PRESSURE ACTING ON SAID PLUNGER ASSEMBLY TO DRIVE SAID PLUNGER ASSEMBLY AWAY FROM SAID FILTER HEAD ASSEMBLY, THE AREA OF SAID PLUNGER ASSEMBLY EXPOSED TO FLUID PRESSURE IN SAID SECOND ACTUATING CHAMBER BEING SUBSTANTIALLY LESS THAN THE AREA OF SAID PLUNGER ASSEMBLY EXPOSED TO FLUID PRESSURE IN THE FIRST-MENTIONED ACTUATING CHAMBER, AND SAID DELIVERY MEANS DELIVERING FLUID UNDER SAID PREDETERMINED PRESSURE TO BOTH SAID FIRST MENTIONED AND SAID SECOND ACTUATING CHAMBERS DURING PRESSING OF THE SLURRY IN SAID PRESSING CHAMBER.