US3645320A

US3645320A - Apparatus for vacuum forming hot top bottom rings

Info

Publication number: US3645320A
Application number: US56481A
Authority: US
Inventors: Anthony J Varrati
Original assignee: Universal Refractories Corp
Current assignee: Universal Refractories Corp
Priority date: 1970-07-20
Filing date: 1970-07-20
Publication date: 1972-02-29
Anticipated expiration: 1989-02-28

Abstract

The method and apparatus for automatically forming a hot top bottom ring from a slurry containing a major portion of granular refractory material, minor portions of inorganic fibrous material and porous refractory material and a resinous binder. The apparatus includes a reservoir containing the slurry, a mold assembly, and a transfer mechanism for moving the mold assembly into and out of the slurry in the reservoir. The mold assembly includes an upper mold member and a lower mold member, the lower member being mounted for movement into engagement with and away from the upper mold member, and a vacuum system operatively connected to the mold assembly to draw the slurry from the reservoir into the mold assembly and to dewater the slurry during the movement of the mold assembly to a dryer screen. The fibrous bottom ring formed in the mold assembly is removed therefrom by the application of air under pressure to deposit the bottom ring on the dryer screen.

Description

United States Patent Varrati 1 Feb. 29, 1972 [54] APPARATUS FOR VACUUM FORMING Primary Examiner-Robert D. Baldwin HOT T()P BOTTOM RINGS Attorney-Ronald E. Barry and James E. Nilles [72] Inventor: Anthony J. Varrati, Milwaukee, Wis. [57] ABSTRACT Assigneel Universal lefractories Corporation The method and apparatus for automatically forming a hot top waukee, Wis. bottom ring from a slurry containing a major portion of granu- [22] Filed: July 20 1970 lar refractory material, minor portions of inorganic fibrous material and porous refractory material and a resinous binder. [2i] Appl- No.1 56, The apparatus includes a reservoir containing the slurry, a mold assembly, and a transfer mechanism for moving the mold [521 U 5 CL 164/160 264/87 assembly into and out of the slurry in the reservoir. The mold [511 mo B28b 1/26 assembly includes an upper mold member and a lower mold 58] Fieid 253 160 264/87 86 member, the lower member being mounted for movement into engagement with and away from the upper mold member, and a vacuum system operatively connected to the mold assembly [56] References cued to draw the slurry from the reservoir into the mold assembly UNITED STATES PATENTS and to dewater the slurry during the movement of the mold assembly to a dryer screen. The fibrous bottom ring formed in 1,880,006 9/1932 Young ..264/87 the mold bl i removed therefrom by the application of 2,73l,699 1/1956 Dubbs ..264/87 X air undelpreSSm-e to deposit h bottom ring on the dryer 3,449,207 6/1969 Modersohn. .264/86 X Screen 3,512,572 5/1970 Ednell ..164/7 X 17 Claims, 9 Drawing Figures /00 64 i /02 u we E l s56 76 78 I l a2 74 a4 g .32 e4 1 r 4 l 72) a I 5 l I l ll 4 l; l! l: fli l I h g l www SHEET 3 OF 4 PATENTEDFEBZS 1912 APPARATUS FOR VACUUM FORMING HOT TOP BOTTOM RINGS BACKGROUND OF THE INVENTION l-Iot top bottom rings of the type shown in Thiem Reissue Pat. No. Re 26,381 issued Apr. 23, I968 generally are formed July 22, 1969 and assigned to the same assignee has resulted in the design of bottom rings of substantially the same materials as used to form the fibrous insert panels. It has been found, however, that the difficulties of automating the formation of bottom rings as experienced in the manufacture of the bottom rings disclosed in the Thiem reissue patent can be overcome when using the fibrous material.

SUMMARY OF THE INVENTION The apparatus of the present invention therefore provides for the automatic formation of fibrous hot top bottom rings from a slurry of granular refractory material, minor portions of inorganic fibrous material and porous refractory material and a resinous binder. This is accomplished by using a novel mold assembly having upper and lower mold sections or members which are adapted to be closed and immersed in the slurry. The slurry is drawn into the mold assembly by a vacuum which is drawn through the mold assembly as the assembly is withdrawn from the slurry to dewater the slurry and form the fibrous bottom ring. It should be noted in this connection that the bottom ring is formed on the upper mold member, thereby assuring that the upper surface of the bottom ring has the exact contour required for mating engagement with the hot top casing and the panel insert unit. In this connection, the fibrous bottom ring when placed in the hot top engages the bottom of the casing and acts as a support for the panel insert unit. The bottom ring is provided with a novel locating arrangement wherein it is only necessary to place the bottom ring in position on the casing and it automatically locates itself with respect to the insert unit.

It is also within the contemplation of the present invention to form the bottom ring within a wiper ring, in such a way that the wiper ring is secured to the outer periphery of the bottom ring. The wiper ring has a small back draft angle between the face leg and the base leg and is placed on the lower mold member of the mold assembly at the start of the cycle of operation. As the slurry is drawn into the mold assembly, it will fill the space between the face leg and base leg of the bottom ring and when dewatered will produce a tight fit around the outer periphery of the bottom ring.

The mold assembly can be modified to form panel insert units for hot tops and side boards for ingot molds. As modified, the mold assembly will provide accurate dimensions for the insert panels and side boards.

Other objects and advantages will become apparent from the following detailed description when read in connection with the accompanying drawings.

THE DRAWINGS FIG. 1 is a front elevation view of the apparatus of this invention with a portion of the front wall broken away to show the mold assembly;

FIG. 2 is a top view of the apparatus showing the mold assembly in the reservoir;

FIG. 3 is an end view taken on line 3-3 of FIG. 1 showing the mold assembly in an open position below the level of the slur- FIG. 4 is a view similar to FIG. 3 with the upper mold member in a release position and the lower mold member supported on a cam plate out of the path of motion of the upper mold member;

FIG. 5 is a view of the bottom ring formed by the present method and apparatus and supported on the dryer screen;

FIG. 6 is a fragmentary sectional view of a hot top showing the fibrous bottom ring of this invention in position below the casing and panel insert unit of the hot top.

FIG. 7 is a sectional view of the mold assembly showing the cavity between the upper and lower mold members taken on line 7-7 of FIG. 1.

FIG. 8 is a section view taken on line 8-8 of FIG. 1 showing the mold assembly leveling arrangement and the lower mold section moving assembly.

FIG. 9 is a section view in elevation showing the vacuum water separating tank.

DESCRIPTION OF THE INVENTION A hot top bottom ring 10 formed by the method and apparatus of the present invention is shown in cross section in FIG. 6 positioned on the bottom of a hot top casing 12 in a position to support a panel insert liner unit 14. This is the general arrangement of the elements which make up a hot top as seen in copending application Ser. No. 843,384. The bottom ring 10 is automatically located on the casing by means of the configuration of the upper surface of the center portion 16 of the bottom ring. In this respect, the bottom ring 10 is pro vided with an outer section 18, the upwardly inclined center portion 16 having a locating surface 20, and an inwardly extending ledge 22. The locating surface 20 is provided at an angle substantially equal to the angle of the bottom surface of the casing 12 for mating engagement therewith when the bottom ring 10 is placed on the casing 12. The ledge 22 underlies the panel insert unit 14 and provides a support for the insert liner unit 14 when the casing 12 is turned right side up.

It should also be noted that a wiper strip 24 is mounted on the outer periphery of section 18 of the bottom ring and includes a base leg 26 and a face leg 28 which meet at an acute angle. A wiper blade 30 extends outwardly from the upper portion of the face leg 28. As pointed out more particularly hereinafter, the acute angle between the base leg 26 and the face leg 28 of the wiper strip assures positive engagement of the wiper strip 24 on the outer periphery of the fibrous bottom ring 10 thereby preventing removal of the wiper strip 24 from the bottom ring. The wiper strip 24 can also be provided with indents in the face leg 28 which become embedded in the fibrous material of the bottom ring.

The bottom ring 10 is formed from a slurry 32 which contains a major portion of granular refractory material, 70-80 parts by weight; minor portions of porous refractory material, 10 parts by weight; and inorganic fibrous material, 12-15 parts by weight; and an organic binder such as phenolic or furan resin, 5-10 parts by weight. This composition is combined with water in the ratio of 15 parts of dry composition to 75 parts water to form the slurry. After the bottom ring 10 has been formed and dried, it should be heat resistant at temperatures below 800 F. and heat destructible at temperatures above l,400 F. The slurry is substantially identical to the slurry disclosed in copending application Ser. No. 843,5 84.

In accordance with the invention, the fibrous bottom ring 10 is formed by means of the automatic molding apparatus 34 which includes a reservoir 36 and a mold assembly 38 mounted on a transfer mechanism 40 for movement from the slurry 32 in the reservoir 36 to a discharge or release position over a dryer screen 42. The reservoir 36 is filled with the slurry 32 and the mold assembly 38 immersed in the slurry 32. Means are provided for drawing a vacuum in the mold assembly 38 to form the bottom ring 10 and to dewater the bottom ring formed in the mold assembly. The mold assembly 38 is moved or transferred from the reservoir 36 and opened to allow the bottom ring 10 to be released from the mold assembly 38 and deposited on a dryer screen 42.

More particularly, and referring to FIGS. 1, 2 and 3, the reservoir 38 includes downwardly sloping bottom walls 44, vertical sidewalls 46, and end walls 48. The slurry 32 is fed to the reservoir 36 by means of a valve 49 provided in a conduit 50 connecting a holding tank 52 to the reservoir 36. The level of the slurry in the reservoir 36 is maintained by means of a float operated switch 54 positioned within the reservoir 36 and electrically connected to open the valve 49.

The mold assembly 38 is supported for movement from the reservoir 36 to the dryer screen 42 by means of the transfer mechanism 40. In this regard, the transfer mechanism 40 includes a pair of support arms 56 secured to pivot shafts 58 which are pivotally mounted in bearing brackets 60 located on the end walls 48. The shafts 58 are rotated by means of a drive mechanism 62 as described hereinafter. A hollow cylindrical tube or conduit 64 is pivotally mounted on the ends of the support arms 56 and includes a number of openings 66.

The fibrous bottom ring is formed in the mold assembly 38 (FIG. 1 and 7) which includes an upper mold member or section 68 and a lower mold member or section 70. The upper section 68 includes a vacuum box 72 secured to the tube 64 by a bracket 74. A screen 76 is connected to the inner and outer walls of the vacuum box 72 and is contoured to provide the upper surface for the bottom ring 10. The vacuum box 72 is connected to the tube 64 by means of a number of hoses 78 connected to the openings 66 in the tube 64 and to openings 82 provided in the four corners of the box 72.

The lower mold member 70 includes a closed box 84 having a screen 86 soldered to the edges of the box 84 to define the contour for the under surface of the bottom ring 10. A number of tubes 88 are provided through the box 84 and screen 86 to provide communication between the interior of the mold assembly 38 and the slurry 32 in the reservoir 36 as described more fully below. The lower mold member 70 is supported on a hollow support tube 90 having a number of holes 92. The lower box 84 is connected to the holes 92 by means of a number of tubes 94.

Means are provided for moving the lower member or section 70 relative to the upper mold section 68 to open the mold assembly 38 after forming the bottom ring 10. Such means is in the form of a support mechanism 96 which includes the hollow support tube 90 and a pair of arms 98 pivotally connected to piston and cylinder assemblies 100. The assemblies 100 are mounted at each end of the vacuum tube or pipe 64. In this regard, the piston and cylinder assemblies 100 each include a cylinder 102 and a piston rod 104 which extends vertically up ward from the cylinder 102. The arms 98 are pivotally connected to the piston rods 104 by pins 106. On actuation of the piston and cylinder assemblies 100 the lower mold member 70 will be moved into and out of engagement with the upper mold member 68.

Means are provided for cross-connecting the piston rods 104 to assure an even and more level movement of the lower mold section 70 into engagement with the upper mold section 68. Such means is in the fonn of a rack 108 provided at the end of the piston rod 104 and a cross rod 110 having a gear 112 secured to each end. The cross rod 110 is rotatably mounted on brackets 114 mounted at each end of the tube 64. By this arrangement, any unbalancing of forces between the piston and cylinder assemblies 1 10 will be transmitted from on assembly to the other by the cross rod 110. The piston and cylinder assemblies 100 are actuated by connecting the cylinders 102 to an air pump 172 through air hoses 115 and 116. The air is controlled by a valve 117 in line 1 15.

After the mold assembly 38 has been immersed in the slurry 32 and closed, a vacuum is drawn in the assembly by means of a vacuum pump 118 connected to a water separation tank 120 which is connected to the end of the tube 64 by means of a valve 122 and a flexible conduit 124 and to the end of tube 90 by means of a valve 126 and a flexible conduit 128. The vacuum drawn in the tubes 64 and 90-draws water from the mold assembly 38 into a water separation tank 120.

In this regard, and referring to FIG. 9, the water separation tank 120 includes a dry-type vacuum pump 118 connected to the top of the tank 120 by conduit 132. The valves 122 and 126 are connected to the tank 120 by means of a conduit 134. Water that is drawn into the tank 120 will accumulate in the bottom of the tank. This water is removed from the tank 120 by means of

pumps

136 and 138 which are connected to the tank by

pipes

140 and 142, respectively. A unique switch arrangement 144 is used to control the water pumps 136 and 138 to prevent damage to the vacuum pump 118. The switch arrangement includes a water' level stop switch 146, a start switch 148, a safety switch 150, and a vacuum pump cutoff switch 152. The stop switch 146 is electrically connected to both

pumps

136 and 138 to stop both pumps whenever the level of water in the tank drops below the switch 146. The start switch 148 is electrically connected to start the pump 136 whenever the level of the water in the tank 120 reaches the start switch 148. In the event of failure of. the pump 136,

the water level will rise to the safety switch 150 which is electrically connected to the pump 138, and will start the pump 138 to remove water from the tank 120. In the event both pumps 136 and 138 fail to start, the water will rise to the cutoff switch 152 which is electrically connected to cut off vacuum pump 118, thereby preventing damage to the vacuum pump.

Means are provided, as shown in FIG. 4, for pivoting the lower mold assembly 70 out of the path of travel of the upper mold member 68 when the bottom ring 10 is to be released from the mold assembly 38 to the dryer screen 42. Such means is in the form of a pair of cam plates 154 provided on each end of the reservoir 36 and a cam roller 156 pivotally mounted on each end of the support tube 90. The cam rollers 156 are pivotally mounted on plates 158 which extend radially outwardly from the tube 90 and are located in a position to engage the surface of the cam plates 154. As the transfer mechanism 40 is pivoted out of the reservoir 36 the rollers 156 will roll around the cam plates 154 pivoting the support arms 98 about the pivot pins 106 on brackets 114. The support arms 98 are positively located with respect to the upper mold section 68 on the return motion of the transfer mechanism 40 by means of slotted guide plates 160 secured to brackets 162 mounted on each end of the support tube 64 below the piston and cylinder assemblies 100.

Means are provided to maintain the upper mold member 68 in a substantially horizontal relation in the movement from the reservoir 36 to the dryer screen 42 as seen in FIGS. 3, 4 and 8. Such means is in the fonn of a first fixed sprocket 164 provided on the housing 60 at one end of the reservoir 36, a second sprocket 166 secured to one end of the tube 64 and a chain 168 connecting the

sprockets

164 and 166. On movement of the pivot arms 56 about their pivot axes, the chain 168 will remain fixed rotating the sprocket 166 as well as tube 64. The

sprockets

164 and 166 have substantially equal diameters so that the tube 64 turns through 180 moving from the reservoir to the dryer screen 42 and back into the reservoir 36.

The fibrous hot top 10 formed in the upper mold section 72 is released therefrom by means of an air pressure system 170 connected to the flexible conduit 124. The air system 170 includes an air pump 172 connected to conduit 124 by a tube 174 and a flexible hose 176. Airflow is controlled by means of a solenoid valve 178 provided in tube 174. Air under pressure is applied to the vacuum box 72 through tube 64 and conduit 78 with sufficient force to blow the fibrous bottom ring 10 onto the dryer screen 42.

Means are provided for aiding in the separation of the lower mold section 70 from the upper mold 68 after the bottom ring 10 has been formed in the mold assembly 38. Such means is in the form of the air pressure system 170 which is connected to the tube 90 by tube 180 and a hose 182. Air pressure to tube 90 is controlled by a solenoid valve 184. Air pressure is applied to the tube 90 by opening valve 184 at approximately the same time as the piston and cylinder assemblies 100 are actuated to separate the

mold sections

68 and 70. This small amount of air under pressure aids in releasing the bottom ring l0'from the lower mold section 74.

Means are provided for moving the transfer mechanism 40 from the reservoir 36 to the dryer screen 42. Such means is in the form of the drive mechanism 62 which is connected to a reversing electric motor 186 mounted at one end of the reservoir 36. The motor 186 includes a magnetic brake for positive stop and a drive sprocket 188 which is connected to a sprocket 190 by chain 192. Drive sprocket 190 is mounted on the end of a drive shaft 194 journaled in bearings 196 provided on each end of the reservoir 36. The motion of the drive shaft 194 is transferred to the pivot shafts 58 by means of sprockets 195 on the drive shaft 194 which are connected to sprockets 198 on the pivot shafts 58 by chains 200.

The cycle of operation of the apparatus is controlled by means of a number of

cams

202, 204, 206, and 208 provided on the end of one of the shafts 58 and a corresponding number of switches 210, 212, 214, and 216 provided on the end of the reservoir 36. A pair of

limit switches

218 and 220 are provided on the bracket 114 for the piston and cylinder assemblies 100 and a number of timers are provided on one end of the reservoir 36 to control various functions in the cycle of operation. Electric wiring of the control circuit is well known and can be easily set up from the following description of the cycle of operation.

The cycle of operation of the apparatus to automatically form a bottom ring is as follows. The reservoir 36 is initially filled with the slurry 32 and the level in the reservoir maintained by means of the float controlled switch 54. At the start of the cycle of operation, the mold assembly 38 is suspended above the slurry in an open position. A wiper strip 24 can be placed on the lower mold section 70 while in this position. The cycle is started by closing a manual start button to start the motor 186 and lower the mold assembly 38 into the slurry 32 in the open position. When the mold assembly 38 is fully immersed in the slurry 32, the motor 186 is stopped by the cam 202 on the pivot shaft 58 which opens a switch 210. This switch will also start a timer which runs for approximately 5 seconds. This timer then actuates the valve 113 to pressurize the piston and cylinder assemblies 100 to close the mold assembly 38. After the mold assembly has closed, the piston rod 104 will engage the limit switch 128 on the bracket 114 starting a vacuum timer, closing valve 113 and opening the two vacuum valves 122 and 126 to the

tubes

64 and 90. The vacuum timer will run for approximately to seconds. The vacuum pump 118 will draw a vacuum in the upper and

lower mold sections

68 and 70. Additional slurry 32 will also be drawn into the mold assembly 38 through the tubes 88 in the lower mold member 70. At the end of the set time period, the vacuum timer will start the motor 186 to move the mold assembly 38 out of the slurry 32 until cam 204 opens switch 212 stopping the motor 186 and opening the valve 113 to the piston and cylinder assemblies 100 to open the mold assembly 38. After the mold assembly 38 has been completely opened, the piston rod 104 will engage the second limit switch 220 on the bracket 114 to close valve 113 to the assemblies 100 and to start the operation of a dryer timer and open vacuum valves 122. The dryer timer will operate for approximately 20 seconds after which the dryer timer will close the vacuum valves stopping vacuum drying of the bottom ring 10 in the upper mold member 68. The dryer timer will start the motor 186 to move the mold assembly 38 to the release position. When the mold assembly reaches the release position, the cam 206 will open switch 214 stopping the motor 186 and energizing the air valve 184 to pressurize tube 64 and force the bottom ring 10 out of the upper mold section 68 onto the dryer screen 42. Opening of switch 214 also closes a circuit to a release timer which closes valve 184 after a period of 5 seconds and starts the motor 186 to return the mold assembly 38 to the start position. On reaching the start position, the cam 216 will open the circuit to the motor 186 to stop the mold assembly 38 in the suspended position over the slurry.

The slurry 32 in the reservoir 36 is continuously agitated whenever the mold assembly 38 is immersed in the slurry to assure even distribution of the fibrous materials throughout the slurry. Agitation is provided by means of a number of

pipes

222, 224, and 226 provided in the bottom of the reservoir 36. The pipes are connected to the air pressure system 170 by a conduit 228 which is controlled by means of a valve 230 connected to the manual control switch. Air under pressure is imparted to the

pipes

222, 224 and 226 whenever the mold assembly 38 is immersed in the slurry. Each of the pipes includes a number of holes along each side to blow air against the bottom walls 44 of the reservoir 36 thereby bubbling the fibrous material throughout the slurry 32. A similar arrangement is provided in the holding tank and is actuated off of the float control switch 54 for the holding tank to commence agitation whenever the level in the reservoir 36 starts to drop and prior to the actuation of the valve 49 which controls the flow of the slurry into the reservoir 36.

The mold assembly 38 can be modified to produce other types of fibrous heat insulating members for use in hot tops and ingot molds such as insert panels for hot tops and side boards for ingot molds. This is accomplished by forming the walls of the upper vacuum box and lower vacuum box in the shape of the insert panels and side boards and mounting filter screens in the boxes to form the inside and outside surface of the panels and side boards. Since the screens will be located a predetermined distance apart, a very accurate thickness can be provided in the panels.

I claim:

1. An apparatus for forming a hot top bottom ring and insert, side boards or any type fiber form from a slurry containing a major portion of granular refractory material, minor portions of an inorganic fibrous material, and a resinous binder, said apparatus including,

a reservoir for the slurry,

a mold assembly for forming the fiber form including an upper mold section and a lower mold section means for moving said lower mold section into and out of engagement with said upper mold section in said reservoir,

means for drawing a vacuum in said mold assembly,

and means for transferring said upper mold section and said lower mold section from said reservoir to a position for releasing the bottom ring from said mold assembly.

2. The apparatus according to claim 1 wherein said moving means includes a pair of pneumatic piston and cylinder assemblies mounted on said transferring means.

3. The apparatus according to claim 1 wherein said transferring means includes means for maintaining said mold assembly in a substantially horizontal position in the movement from the reservoir to the release position.

4. The apparatus according to claim 3 wherein said maintaining means includes a sprocket fixedly mounted on said assembly, a hollow tube for supporting said mold assembly, a second sprocket secured to one end of said tube, and a chain interconnecting said sprockets.

5. The apparatus according to claim 1 including means for pivoting said lower mold section out the path of motion of said upper mold section.

6. The apparatus according to claim 5 wherein said pivoting means comprises a pair of cam plates positioned at each end of said reservoir, a pair of arms pivotally connected to said upper section and a pair of cam rollers positioned to engage the cam plates on movement of said mold assembly from said slurry to said release position.

7. The apparatus according to claim 1 including means for applying air under pressure to said upper mold section to release the bottom ring from said upper mold section.

8. An apparatus for forming a bottom ring from a slurry containing a major portion of granular refractory material, and a minor portion of inorganic fibrous material, the apparatus comprising,

a reservoir for the slurry,

means for maintaining a predetermined level of slurry within the reservoir, a mold assembly having an upper section an a lower section, means for moving said lower mold section into and out of engagement with said upper mold section in said reser- V011,

means for transferring said mold assembly from a position below the level of the slurry in the reservoir to a release position,

means for applying a vacuum to said upper mold section and said lower mold section when immersed in the slurry,

and means for applying air under pressure to said upper mold section when said upper mold section is in the release position.

9. The apparatus according to claim 8 wherein said transferring means includes means for maintaining said upper mold section in a horizontal position in the movement from said reservoir to said release position.

10. The apparatus according to claim 8 including means for supporting said lower mold section on said transferring means for pivotal movement out of the path of said upper section.

11. The apparatus according to claim 9 including means for applying air under pressure to said lower mold section prior to separating said lower section from said upper mold section.

12. An apparatus for forming a hot top bottom ring, said apparatus comprising,

a vacuum mold assembly including an upper mold section having a screen shaped to define the upper surface of the bottom ring, and a lower mold section having a screen to define the lower surface of the bottom ring,

means for immersing said assembly in a slurry containing minor portions of inorganic fibrous material and porous refractory material,

means for closing said upper mold section and said lower mold section trap the slurry in the cavity formed between said screens,

said means for drawing a vacuum in said upper mold section and said lower mold section.

13. The apparatus according to claim 12 including means for admitting additional slurry into said cavity formed on clos ing said assembly.

14. The apparatus according to claim 12 including means on said lower mold section for retaining a bottom ring on the periphery of said lower mold section.

15. The apparatus according to claim [2 including means for agitating the slurry whenever said mold assembly is immersed therein.

16. An apparatus forming a fibrous heat insulating member for use in a hot top or ingot mold, said apparatus comprising a vacuum mold assembly including an upper mold section having a screen shaped to define the upper surface of the member, and a lower mold section having a screen to define the lower surface of the bottom ring,

means for immersing said assembly in a slurry containing a major portion of granular refractory material and minor portions of inorganic fibrous material and porous refractory material,

means for closing said upper mold section and said lower mold section to trap the slurry in the cavity formed between said screens,

and means for drawing a vacuum in said upper mold section and said lower mold section.

17. The apparatus according to claim 16 including means for admitting additional slurry into said cavity.

Claims

1. An apparatus for forming a hot top bottom ring and insert, side boards or any type fiber form from a slurry containing a major portion of granular refractory material, minor portions of an inorganic fibrous material, and a resinous binder, said apparatus including, a reservoir for the slurry, a mold Assembly for forming the fiber form including an upper mold section and a lower mold section means for moving said lower mold section into and out of engagement with said upper mold section in said reservoir, means for drawing a vacuum in said mold assembly, and means for transferring said upper mold section and said lower mold section from said reservoir to a position for releasing the bottom ring from said mold assembly.

8. An apparatus for forming a bottom ring from a slurry containing a major portion of granular refractory material, and a minor portion of inorganic fibrous material, the apparatus comprising, a reservoir for the slurry, means for maintaining a predetermined level of slurry within the reservoir, a mold assembly having an upper section an a lower section, means for moving said lower mold section into and out of engagement with said upper mold section in said reservoir, means for transferring said mold assembly from a position below the level of the slurry in the reservoir to a release position, means for applying a vacuum to said upper mold section and said lower mold section when immersed in the slurry, and means for applying air under pressure to said upper mold section when said upper mold section is in the release position.

12. An apparatus for forming a hot top bottom ring, said apparatus comprising, a vacuum mold assembly including an upper mold section having a screen shaped to define the upper surface of the bottom ring, and a lower mold section having a screen to define the lower surface of the bottom ring, means for immersing said assembly in a slurry containing minor portions of inorganic fibrous material and porous refractory material, means for closing said upper mold section and said lower mold section trap the slurry in the cavity formed between said screens, said means for drawing a vacuum in said upper mold section and said lower mold section.

13. The apparatus according to claim 12 including means for admitting additional slurry into said cavity formed on closing said assembly.

15. The apparatus according to claim 12 including means for agitating the slurry whenever said mold assembly is immersed therein.

16. An apparatus forming a fibrous heat insulating member for use in a hot top or ingot mold, said apparatus comprising a vacuum mold assembly including an upper mold section having a screen shaped to define the upper surface of the member, and a lower mold section having a screen to define the lower surface of the bottom ring, means for immersing said assembly in a slurry containing a major portion of granular refractory material and minor portions of inorganic fibrous material and porous refractory material, means for closing said upper mold section and said lower mold section to trap the slurry in the cavity formed between said screens, and means for drawing a vacuum in said upper mold section and said lower mold section.