US3684000A - Mold making device having blow nozzle - Google Patents

Abstract

A series of expendable shell molds is formed in a permanent pattern having a series of connected mold cavities. A passage including the cavities extends through the pattern. A swinging blow-vent nozzle is mounted at each end of the passage, the two nozzles being rotationally fixed to each other. In one position the first nozzle blows into the pattern while the second nozzle vents the pattern. In a second position the second nozzle blows into the pattern while the first nozzle vents the pattern. In a third position one of the nozzles blocks the passage while the other has been swung out of the way to provide access for a sand blow box which can then blow sand into the pattern. The nozzles are clamped against the pattern by a hydraulic cylinder which moves them toward each other on a shaft. The device includes means for separating the pattern, lifting the gang of molds out of the pattern and stripping the molds from pins on which they are formed or by which they are lifted. The device for elevating the finished molds includes means for blowing out the molds as the patterns are raised. The apparatus is particularly suitable for making cores for making tappet bodies and for making molds for casting engine valves.

Description

[ 3,684,000 [451 Aug. 15, 1972 MOLD MAKING DEVICE HAVING Primary Examiner-4. Spencer Overholser BLOW NOZZLE Assistant Exarniner-John S. Brown 72 Inventor: Walter H. Van Deberg, Berkley, chslwlm [73 A Tho Man I I [57] ABS CT 1 1 u actunng A series of expendable shell molds is formed in a per- Co., Ferndale, Mich. t

. manent pattern having a series of connected mold S- 1969 v cavities. A passage including the cavities extends through the pattern. A swinging blow-vent nozzle is mounted at each end of the passage, the two nozzles being rotationally fixed to each other. in one position United States Patent Van Deberg 221 Filedi 211 Appl. No; 853,913

the first nozzle blows into the pattern while the second nozzle vents the pattern. In a second position the second nozzle blows into the pattern while the first nozzle vents the pattern. In a third position one of the nozzles blocks the passage while the other has been swung out of the way to provide access for a sand blow box which can then blow sand into the pattern. The nozzles are clamped against the pattern by a hydraulic cylinder which moves them toward each other on a shaft. The device includes means for lifting the gang of molds out of ping the molds from. pins on which they are formed or by which they are lifted. The device for elevating the finished molds includes means for blowing out the molds as the patterns are raised. The apparatus is particularly suitable for making cores for making tappet bodies and for making molds for mm a u s v M m e 3 m .m gm g mm m a g m .m Pe w Rm c 9 1 7 3 i 000 NHH 1 O OOO 90043 7277222 452 I r 66/// 61 3 9134M, 4 2444 .I. 03330 /6//666 x 39 ,3 41 111 mz mz 6 m m mm 2 37 6 A 0 I m S mm m 7 ,8 m U U m m 222 9 uunnnuu muw337 m mummnnu 9 9 u u "u m..oo zuufLrn M A nnnn uen "0 33 O P u" d" m"2 Sm nnm 5 ..7.3 E o ak .4 m S1l l1 "#6 T 0fleehae "m m A DBhBCCB mnu 7 r. T u m mmwww .m S m 1 a e D 17236 "a ,3 Rv 2345 666 U 6 9999999 m m 2031 W HHHHHHH mm M nt- N 52 482 imm cw4 U d Std 1 844354 nnl 210087 2 UIF J V mm wmfi 1]] l .218 6 UUU. U. 1222333 11 Claims, 17 Drawing Figures ll H l |ill ll ll ll ll PATENTEDAUB 15 1912 SHEET 1 OF 5 F'IGI Illllllllilllllll FIG. l-L

Jlllllllllllllll L PATENTED 15 1912 3.684; 000

SHEET 2 BF 5 74 66 I56 it 64 64 FIG. 4-R

PATENTEU I973 3,684,000

7 FIG? PATENTEDAUB 15 1972 SHEET 5 OF 5 FIG. 9

MOLD MAKING DEVICE HAVING BLOW NOZZLE This invention relates to the making of molds for exampleshell molds for making metal castings, particularly to apparatus for applying parting agent to permanent patterns, delivery of mold forming material into the pattern cavity and removal of finished molds from the pattern.

In order to help separate finished shell molds from the pattern, the walls of the cavity which determine and shape the mold are coated with a parting agent such as a silicone oil, which may be applied before each mold is formed or at intervals in a repetitive process of forming molds. In customary processes the parting agent is sprayed on exposed cavity surfaces with an open pattern with an air suspension or mist of the parting agent. But the parting agent also coasts the surfaces of the separation of the pattern. This retains particles of dust or fine sand which may be dislodged from the finished molds. Such particles may prevent the subsequent precise meeting of the mold halves and prevent precise closing of the pattern. To avoid this I provide apparatus which sprays the parting agent into a pattern which is accurately mated and precisely closed.

With molds of complicated cavity shapes or with a long series of cavities, it is sometimes difficult to coat the surfaces evenly and the last cavity in the series may not have received enough.

One of the objects of the invention is to provide improved apparatus which will reliably and evenly apply parting agent to a closed mold.

Another object of the invention is to provide an improved mold coating apparatus which can be used with sand blowing apparatus of any suitable form and which has coordinated power and control for coordinating the pattern coating apparatus and the sand blowing apparatus.

Another object is to provide improved apparatus for lifting the finished molds out of the pattern and for stripping the finished molds from core pins or ejection pins.

' These and other objects of the invention will be understood from the following description and from the accompanying drawings which disclose, for illustration only and not by way of limitation, one form of im proved apparatus embodying my invention.

FIG. 1 is a diagrammatic partial front elevation of a pattern and of blowing devices embodied in my improved machine, at one stage of the process of forming a series of shell molds (the sand blowing device being in the inoperative position).

FIG. 1L is a schematic partial left side elevation of the pattern with the left hand blow-vent nozzle at the stage shown in FIG. 1, at the position to vent the pattern at the left.

FIG. IR is a schematic partial right side elevation of the pattern with the right hand blow-vent nozzle at the stage shown in FIG. 1, in position to blow parting agent into the mold from the right, the sand blowing device being omitted.

FIG. 2 is a partial front elevation corresponding to FIG. 1 at a subsequent position of the machine with the blow-vent nozzles clamped against the pattern.

FIG. 3 is an elevation corresponding to FIG. 2 at a later stage of the process of forming the molds in which the pattern is blown from the left.

FIG. 3L is an elevation corresponding to FIG. 1L of the pattern with the left hand blow-vent nozzle at the stage shown in FIG. 3 and in position to blow parting agent into the mold from the left.

FIG. 3R is an elevation corresponding to FIG. 1R of the pattern with the right hand blow-vent nozzle at the stage shown in FIG. 3 and in position to vent the mold at the right.

FIG. 4 is an elevation corresponding to FIG. 2 at a still later stage in the process of making the molds in which one blow-vent nozzle is out of the way and the sand blowing device is in the operative position.

FIG. 4L is an elevation corresponding to FIG. 3L of the pattern with the left hand blow-vent nozzle at the stage shown in FIG. 4 in position to block the left end passage into the pattern.

. FIG. 4R is an elevation corresponding to FIG. 3R of the pattern, blow-vent nozzle, and sand blow box in position to blow sand into the mold from the right.

FIG. 4R is an elevation corresponding to FIG. 4R at a later stage of operation showing the pattern separated and the shell molds ejected from it in position to be removed from their cores.

FIG. 5 is a fragmentary front elevation, partly in section, corresponding to FIG. 1 showing one form of structure of means for supporting cores in the pattern and for ejecting finished shell molds from the pattern.

FIG. 6 is an enlarged structural section through one form of pattern for making tappet cores, taken on the line 6-6 of FIG. 5 which is also on the line 6-6 of FIG. 7.

FIG. 7 is a structural section of a single cavity of a pattern on the line 7-7 of FIG. 6 which corresponds to the line 7 --7 of FIG. 3-R.

FIG. 8 is a structural section corresponding to FIG. 6 (and on the line 8--8 of FIG. 9) of a single cavity in another form of pattern (for making shell molds for engine valves) showing the core in place.

FIG. 9 is a section on the line 9-9 of FIG. 8.

FIG. It) is a perspective of a pair of molds (one cut away) made in the pattern of FIGS. 6 and 7.

DEFINITIONS As used herein pressure gas means any gas under pressure, including, without limitation, air and superheated steam.

Sand means any granular mold forming material adapted to be packed into a cavity and cured to form a mold. One example, without limitation issilica sand, the grains of which have been coated with a curable binder.

Mold means any structure into or around which molten metal may be cast. This includes both hollow molds into which metal may be cast, and cores around which metal is cast.

The invention provides an improved machine which is particularly adapted to making the cores 2% shown in FIG. 10 or hollow molds, made in space 22 in the pattern of FIG. 8. The cores 2!) are used in casting hydraulic valve lifters (tappets) of the form shown in the U.S. Pat. to Thompson, No. 3,412,721, Nov. 26, 1968. These cores are formed with a vent space 24 by a permanent core or pin. The hollowmold of FIG. 9 is for casting an engine valve as shown in the U.S. Pat. to Thompson No. 3,395,747, Aug. 6, 1968, and is made over a permanent core 26 of the form of the finished valve casting.

As shown in FIGS. 1-3 a pattern having two separable halves 30, 32 mounted on supporting bars 34 is provided with a series of generally cylindrical cavities 36 indicated in dotted lines in FIGS. 1, 4 and and in solid lines in FIGS. 6 and 7. The cavities are connected by a passage 38 extending entirely through the pattern from one end to the other. On the left end of the mold is a blow-vent nozzle 40 keyed to a rotatable shaft 42 which at its right end carries a sleeve 44 to which is keyed a second blow vent nozzle 46. The sleeve can slide axially but not rotate with respect to the shaft. The blow vent nozzles can be moved apart to the position shown in FIG. 1 or moved together to the position shown in FIG. 2 (in which they are clamped against the ends of the pattern) by any suitable control device, herein schematically represented by a double acting hydraulic cylinder 48 mechanically fixed to the sleeve 44 and carrying a piston 50 mechanically connected to the shaft 42 The cylinder is controlled by hydraulic lines 54 and 56. Superior pressure in the line 54 separates the nozzles as shown in FIG. 1. Superior pressure in the line 56 clamps the nozzles against the ends of the pattern as shown in FIG. 2. The. lines may be pressurized and timed by any suitable apparatus, for example that shown (FIG. 13) of the US. Pat. to Thompson, No. 3,071,929, Jan. 8, 1963, the disclosure of which is incorporated herein by reference. Connection of the line 56 to the line 640a in that patent, pressurized by the cam 628a and connection of the line 54 to the return reservoir at the line 644 will accomplish this result.

The nozzles 40 and 46 each consist of a flat plate which as shown in FIGS. 1L and IR has through it a blow opening 58 connected to an air supply pipe 60 and a vent opening 62. In FIG. 1L and IR the vent opening is indicated diagrammatically by a triangle and the blow opening is indicated by a circle. These openings are disposed on an arc whose center is the center of shaft 42 so that as the shaft is rotated the blow openings and vent openings can be swung selectively opposite the passage 38. The shaft 42 may be rotated with sleeve 44 by a piston 64 in a double acting hydrauliccylinder 66 controlled by lines 68 and 70. Superior pressure in the line 68 moves the piston as far into the cylinder as it can go and places the nozzles 40, 46 in one extreme condition in which the nozzle 46 can blow into the right end of the passage 38 while the nozzle 40 vents the left end of the passage. As shown in FIGS. 3L and 3R superior pressure in line 70 tends to move the piston out of the chamber and place the nozzles in an intermediate position in which a tail 72 on nozzle 40 is held against a stop 74 set by a spring. This holds the nozzles in position to blow into the left end of the passage 38 and vent the right end to the passage. Each of the vent openings 62 is provided with a choke or fixed orifice having a controlling cross section less than the controlling cross section of the passage 38 so that the desired pressure will be maintained throughout the cavity to deposit the required amount of parting agent. Each pipe 60 is supplied with a gaseous suspension of parting agent under pressure from a source of pressure 76 under the control of a valve 78 operated by a double acting hydraulic cylinder 80 whenever it is desired to blow through that particular nozzle.

The nozzle 40 has a second tail 82 which can block the passage 38 at the left end whenever the nozzle 42 is in the position shown in FIG. 4L. it can be put in this position whenever an electrical circuit 84 removes the spring held stop 74 from its stopping position in the path of tail 72 shown in FIG. 3L to the passing position shown in FIG. 4L. The electrical circuit 84 can be energized at the appropriate time in the cycle of operation by any suitable device such as any suitable switch operated by the cam shaft 236 in FIG. 5 of the Reissue US. Pat. No. 26,218 to Thompson, June 6, 1967 the disclosure of which is incorporated herein by reference.

It is contemplated that the machine will perform the cycle of operations shown in FIG. 7 and described in the specification of the application filed by me and Thompson, et al. referred to herein. When the molds have been cured, the pattern is separated, the molds are ejected therefrom and the molds are stripped from the cores on which they are formed as indicated diagrammatically in FIG. 4R. The shafts 34 may be moved toward and away from each other by double acting hydraulic cylinders actuated by a hydraulic separating line 92 and a hydraulic closing line 94 which lines may be pressurized as disclosed in the Reissue patent referred to. When the pattern halves 30 and 32 are separated as shown in FIG. 4R a double acting hydraulic cylinder 96 may be operated by suitable connections to the system shown in the Reissue patent to elevate pin core bar 98 (carrying core pins 100) by means of a bell crank lever I02, link I04 and core elevator 1106. Thereafter a stripping fork 168 is moved from the full line position shown in FIG. 4R to the dotted line position underneath the molds M0, the cylinder 96 is pressurized to lower the support 106 and the molds are thereby stripped from the pins. Thereafter the stripping fork 108 may be moved back to its full line position and the molds removed in any suitable manner. The stripping fork is moved in and out by any suitable linkage as shown, actuated by the double acting hydraulic cylinder 112 connected to the system shown in the reissue patent by hydraulic lines 114 and I 16.

FIGS. 5, 6 and 7 show one form of actual structure of the pattern. Pattern halves 36-32 meet along a parting line 118 and may have split bushings or liners 126 each pair of which mates to form one of the cavities 36. One pin core 100 projects through the connecting passage 38 into each cavity 36 to form the vent opening 24 shown in FIG. 10. The pin cores are supported on studs 124 projecting upwardly from pin core bar 98 attached and connected to an air supply manifold 128 (FIG. 5) secured to the upper end of a pair of guide bars 130 slidable vertically in a guide 132 and connected to the elevator rod 106. One of the guide bars may be hollow, to form an air supply conduit which feeds air under pressure to the air manifold 128 which in turn feeds it through a connection 134 to the interior of the pin core bar 98. The latter is perforated to provide air blast nozzles 140, which as the pin core bar is raised through the separated pattern parts 30 and 32, blows air over the pattern surfaces to dislodge any loose sand or dust which may have been left thereby by the mold.

The entire structure shown in FIG. 5 and its control apparatus may be duplicated allochirally about a plane represented by the center line C-L in FIG. 5, this duplication being indicated in FIG. 5 by a second blow vent nozzle 40.

After the pattern has been satisfactorily coated with parting agent sand is blown into the mold. A sand blow box 150 (FIG. 1) constructed and operated as more fully described in the application referred to by me and Thompson, et al., may be used. This blow box is tilted to the position of FIG. 1 out of the path of the blow vent nozzle 46 whenever the blow-vent nozzles are in any position except that shown in FIGS. 4L and 4R.

When the blow nozzles are in this position however the sand blow box is moved to the position of FIG. 4 and its sand blow nozzle 152 is pressed against the end of the pattern 30, 32. Then sand is blown into the pattern by compressed air supplied to a fitting 154 from a pressure source 156 under control of a blow valve 158 operated by any suitable hydraulic power and timing cylinder 160. After the pattern is packed with sand the sand blow box is swung away from the pattern to the position shown in FIG. 1, and the molds are removed from the pattern as described above and shown schematically in FIG. 4R. Then the pattern is closed, coated with parting agent again if necessary, and the process is repeated.

I claim as my invention.

1. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of rotatable blow-vent nozzles, one at each end of the passage, for coating the pattern with a parting agent, means for selectively holding the nozzles against the pattern and releasing them, means for supplying the nozzles with a gaseous suspension of parting agent, means on one nozzle for blocking one end of the passage through the pattern, means for rotating the nozzles to a first position in which the first nozzle can blow into the pattern while the second nozzle vents the pattern, to a second position in which the first nozzle vents the pattern while the second nozzle can blow into the pattern, and to a third position in which the second nozzle blocks the pattern passagewhile the first nozzle is removed from the pattern passage, means for flowing sand into the pattern passage when the first nozzle is removed, means for opening the pattern, means for lifting molds from the pattern, means for stripping the molds from the lifting means and a coordinated moving and control mechanism for operating the nozzle ho1ding means, nozzle rotating means, suspension supply means, sand blowing means, pattern opening means, lifting means and stripping means in a predetermined timed relation.

2. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening, means for moving the nozzles selectively to a first position in which the first nozzle can blow into the passage while the second nozzle vents the passage and to a second position in which the first nozzle vents the passage while the second nozzle can blow into the passage and to a third position in which one nozzle blocks the passage while the other nozzle is removed from the passage, means for flowing sand into the pattern, means for moving the flowing means to and away from the passage, and coordinated means for moving the nozzles to the third position and moving the flowing means to the passage.

3. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening, means for moving the nozzles selectively to a first position in which the first nozzle can blow into the passage while the second nozzle vents the passage and to a second position in which the first nozzle vents the passage while the second nozzle can blow into the passage and to a third position in which one nozzle blocks the passage while the other nozzle is removed from the passage, and means for flowing sand into the passage when the nozzles are in the third position.

4. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening, means for moving the nozzles selectively to a first position in which the first nozzle can blow into the passage while the second nozzle vents the passage and to a second position in which the first nozzle vents the passage while the second nozzle can blow into the passage and to a third position in which one nozzle blocks the passage while the other nozzle is removed from the passage.

5. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening whose controlling cross section is less than the controlling cross section of the passage, and means for moving the nozzles selectively to positions for blowing into the passage and for venting into the passage, the moving means being so arranged that when one nozzle can blow into the passage, the other vents the passage.

6. A device for making molds comprising in combination a pattern having-a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening, and means for moving the nozzles selectively to positions for blowing into the passage and for venting into the passage, the moving means being so arranged that when one nozzle can blow into the passage, the other vents the passage.

7. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a blow-vent nozzle, means for moving the nozzle to a first position for blowing a suspension of parting agent into one end of the passage and to a second position for venting the passage and to a third position in which the nozzle is removed from the passage.

8. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a nozzle having a blow opening and a vent opening of a controlling cross section less than the controlling cross section of the passage, means for moving the nozzle to a first position for blowing a suspension of parting agent into one end of the passage and to a second position for venting the passage.

9. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a blow-vent nozzle, means for moving the nozzle to a first position for blowing a suspension of parting agent into one end of the passage, to a second position for venting the passage, and to a third position for blocking the passage.

10. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of rotatable blow-vent nozzles, one at each end of the passage, for coating the pattern with a parting agent, means for selectively holding the nozzles against the pattern and releasing them, means for supplying the nozzles with a gaseous suspension of parting agent, means on one nozzle for blocking one end of the passage through the pattern, means for rotating the nozzles to a first position in which the first nozzle can blow into the pattern while the second nozzle vents the pattern, to a second position in which the first nozzle vents the pattern while the second nozzle can blow into the pattern, and to a third position in which the second nozzle blocks the pattern passage while the first nozzle is removed from the pattern passage, means for flowing sand into the pattern passage when the first nozzle is removed, means for opening the pattern, a perforate ejecting support, means for supplying pressure gas to the support, means responsive to opening the pattern for moving the support between the separated parts of the pattern to remove finished molds and wash the pattern with pressure gas, means for stripping the molds from the lifting means and a coordinated moving and control mechanism for operating the nozzle holding means, nozzle rotating means, suspension supply means, sand flowing means, pattern opening means, and stripping means in a predetermined timed relation.

11. A device for making molds comprising in combination a separable pattern having through it a passage including a cavity for making molds, means for blocking one end of the passage and flowing sand into the other end, means for separating the pattern, an ejecting support, means responsive to separating the pattern for moving the support to remove finished molds from the pattern, means responsive to moving the support for washing the pattern with pressure gas and a coordinated moving and control mechanism for operating in a predetermined timed relation the flowing means and separating means.

Claims (11)

1. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of rotatable blow-vent nozzles, one at each end of the passage, for coating the pattern with a parting agent, means for selectively holding the nozzles against the pattern and releasing them, means for supplying the nozzles with a gaseous suspension of parting agent, means on one nozzle for blocking one end of the passage through the pattern, means for rotating the nozzles to a first position in which the first nozzle can blow into the pattern while the second nozzle vents the pattern, to a second position in which the first nozzle vents the pattern while the second nozzle can blow into the pattern, and to a third position in which the second nozzle blocks the pattern passage while the first nozzle is removed from the pattern passage, means for flowing sand into the pattern passage when the first nozzle is removed, means for opening the pattern, means for lifting molds from the pattern, means for stripping the molds from the lifting means and a coordinated moving and control mechanism for operating the nozzle holding means, nozzle rotating means, suspension supply means, sand blowing means, pattern opening means, lifting means and stripping means in a predetermined timed relation.

2. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening, means for moving the nozzles selectively to a first position in which the first nozzle can blow into the passage while the second nozzle vents the passage and to a second position in which the first nozzle vents the passage while the second nozzle can blow into the passage and to a third position in which one nozzle blocks the passage while the other nozzle is removed from the passage, means for flowing sand into the pattern, means for moving the flowing means to and away from the passage, and coordinated means for moving the nozzles to the third position and moving the flowing means to the passage.

3. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening, means for moving the nozzles selectively to a first position in which the first nozzle can blow into the passage while the second nozzle vents the passage and to a second position in which the first nozzle vents the passage while the second nozzle can blow into the passage and to a third position in which one nozzle blocks the passage while the other nozzle is removed from the passage, and means for flowing sand into the passage when the nozzles are in the third position.

4. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening, means for moving the nozzles selectively to a first position in which the first nozzle can blow into the passage while the second nozzle vents the passage and to a second position in which the first nozzle vents the passage whiLe the second nozzle can blow into the passage and to a third position in which one nozzle blocks the passage while the other nozzle is removed from the passage.

5. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening whose controlling cross section is less than the controlling cross section of the passage, and means for moving the nozzles selectively to positions for blowing into the passage and for venting into the passage, the moving means being so arranged that when one nozzle can blow into the passage, the other vents the passage.

6. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of blow-vent nozzles, one at each end of the passage, each nozzle having a blow opening and a vent opening, and means for moving the nozzles selectively to positions for blowing into the passage and for venting into the passage, the moving means being so arranged that when one nozzle can blow into the passage, the other vents the passage.

7. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a blow-vent nozzle, means for moving the nozzle to a first position for blowing a suspension of parting agent into one end of the passage and to a second position for venting the passage and to a third position in which the nozzle is removed from the passage.

8. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a nozzle having a blow opening and a vent opening of a controlling cross section less than the controlling cross section of the passage, means for moving the nozzle to a first position for blowing a suspension of parting agent into one end of the passage and to a second position for venting the passage.

9. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a blow-vent nozzle, means for moving the nozzle to a first position for blowing a suspension of parting agent into one end of the passage, to a second position for venting the passage, and to a third position for blocking the passage.

10. A device for making molds comprising in combination a pattern having a through passage including a mold cavity, a pair of rotatable blow-vent nozzles, one at each end of the passage, for coating the pattern with a parting agent, means for selectively holding the nozzles against the pattern and releasing them, means for supplying the nozzles with a gaseous suspension of parting agent, means on one nozzle for blocking one end of the passage through the pattern, means for rotating the nozzles to a first position in which the first nozzle can blow into the pattern while the second nozzle vents the pattern, to a second position in which the first nozzle vents the pattern while the second nozzle can blow into the pattern, and to a third position in which the second nozzle blocks the pattern passage while the first nozzle is removed from the pattern passage, means for flowing sand into the pattern passage when the first nozzle is removed, means for opening the pattern, a perforate ejecting support, means for supplying pressure gas to the support, means responsive to opening the pattern for moving the support between the separated parts of the pattern to remove finished molds and wash the pattern with pressure gas, means for stripping the molds from the lifting means and a coordinated moving and control mechanism for operating the nozzle holding means, nozzle rotating means, suspension supply means, sand flowing means, pattern opening means, and stripping means in a predetermined timed relation.

11. A device for making molds comprising in combination a separable pattern having through it a passage including a cavity for making molds, means for blocking one end of the passage and fLowing sand into the other end, means for separating the pattern, an ejecting support, means responsive to separating the pattern for moving the support to remove finished molds from the pattern, means responsive to moving the support for washing the pattern with pressure gas and a coordinated moving and control mechanism for operating in a predetermined timed relation the flowing means and separating means.

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