US1856166A - Apparatus for molding helical castings - Google Patents

Description

y 1932- c. E. NORDF-ELDT ET AL 1,856,166

APPARATUS FOR MOLDING HELICAL CASTINGS m im m MWA 0. W 5M a VV 1 Kw MW n 1 M y 3, 1 c. E. NORDFELDT ET AL 1,855,166

APPARATUS FOR MOLDING HELICAL CASTINGS Filed Nov. 2, 1931 2 Sheets-Sheet 2 1N VEN TORS 0. E Nomlfeldi WJAh lquisl' BY 1'. ME'mel y W ATTORNEYS Patented May 3, 1932 UNlTED STATES PATENT OFFICE CHARLES E. NORIJFELIDT, WALTER J. AHLQUIST, AND IRWIN M, EMERY, OF MASSILLON, OHIO, ASSIGNORS TO THE MASSILLON STEEL CASTING COMPANY, OF MASSILLON,

OHIU, .A CORPORATION OF OHIO APPARATUS FOR MOLDING HELIGAL CASTINGS Application filed November 2, 1931. Serial No. 572,472.

T he invention relates to casting helical articles such as helical screw or worm, conveyors consisting of a shaft portion provided with one or more helical threads or projections, and more particularly to molding apparatus for producing molds in which such helical articles may be cast.

Cast steel helical screw conveyors are 8X- tensively used in furnace stokers, but their manufacture has heretofore been very eX- pensive because of the ditliculties encountered in casting the same. According to common practice, such helical conveyor worms are made by providing a bed of sand in a flask, laying a pattern provided with a helically arranged thread on the bed of sand, and ramming sand around the pattern to fill the flask. The pattern is then screwed out of the rammed sand, the necessary vents, cores, and

pouring sprues are provided, and molten metal is poured into the mold.

In so casting helical worms it is quite dilil cult to keep the pattern straight in the flask during the ramming operation. Moreover, if the ram contacts with the pattern while ramming, a defect will occur on he casting at the place where the pattern was struck by the ram, Moreover, it is ditiicult, if not impossible, to uniformly ram sand around the hel cally arranged projecting portion of a pattern. Thus the rammed sand does not have a uniform density and the casting made in the in old has swells and defects thereon resulting from the varying densityvof the mold sand.

Iiloreover, the preparation of the mold be done substantially entirely by hand and one workman can usually only prepare from three to six molds during a working day and if defects occur in the mold, they r be corrected since the mold cannot be ed. Tlfhus, the yield of acceptable castis frequently quite low, while the cleanand strc htening-z' costs for finishing the 3;; is V0.1. high due to the defects which nuist be corrected so that the castings may inspection. it is an object of the present invention to provide mechanical apparatus for producing molds in which helical articles may be cast.

is a further object of the present invention to provide molds for casting helical articles in whichthe sand is rammed to uniform density throughout, in which the density of the sand immediately surrounding the mold cavity is increased, and in which the surface of the mold cavity is very smooth and firm so as to eliminate the formation of swells or defects on the surfaces of articles cast therein.

It is a further object of the present invention to eliminate the possibility of having the pattern hit during the ramming operation so as to avoid defects in the casting resulting therefrom, and to provide for introducing a. helical pattern into a rammed flask in a truly straight line.

Moreover, it is an object of the present invention to produce molds for casting helical articles which are uniformly perfect, which do not require any dressing operations after removal of the pattern, and which will give high yield of substantially perfect castings.

It is another object of the present invention to provide for the casting of helical articles so that the final cleaning and straightening costs of the resulting castings will be eX- tremely low.

It is a further object of the present invention to provide means for readily preparing molds for helical castings of different lengths, and of varying diameters; and to readily prepare molds for helical castings in which the thickness of the helical thread may vary throughout its length.

And finally, it is an object of the present invention to provide apparatus for preparing molds for helical castings, the use of which will enable a very small number of laborers to prepare very large numbers of molds during an ordinary working day.

These and other objects may be obtained by the inventions, improvements, combinations, devices, and elements, preferred. em bodiments of which are shown in the drawings, and hereinafter described in detail, which may be stated in general terms as including in apparatus for making molds for helical. articles, a table, a four-sided flask removably mounted on the table including one bottom wall, two side walls and one end pattern carried by the plate, longitudinallymovable means for rotatably moving the pattern through said nutinto and outof rammed sand in the flask, and means for normally urging movement of the pattern axially toward the flask.

In the drawings,

Figure 1 is a side elevation, certain parts.

being broken away in section, of the improved molding apparatus showing a flask having rammed sand therein clamped against the table plate for having the helical pattern screwed into the rammed sand;

Fig. ,2 is a fragmentary longitudinal sectional view, generally similar to Fig. 1, but showing the helical pattern partially screwed into the rammed sand;

Fig. 3 is a view similar to 2 showing a helical impression completely formed in the sand and showingthehelical pattern partially withdrawn from the flask;

Fig. 4 is a longitudinal sectional view through a mold made by the improved apparatus just prior to being poured;

Fig. 5 is a side elevationof a helical worm or screw conveyor cast in the :mold shown in Fig. 4;

Fig. 6 is a perspective view of .a four-sided flask and its removable top wall;

7 is a longitudinal sectional view through a pattern supporting and clamping device which may be used in connection with the device shown in Figs. 1 to '3 inclusive, particularly when molds are being prepared for helical articles having a varying thickness of helical thread, taken on the line 7 -7 Fig. .8 and Fig. 8 is a cross-section taken on the line 88,, Fig. 7.

Similar numerals refer to similar parts throughout the drawings.

The improved apparatus for making molds for helical castings includes a bed or table 1, and a plate 2 is rigidly mounted on the table 1 to project upwardly from the table intermediate the ends thereof. The plate 2 divides the table 1 to provide a flask end A. and a carriage end B therefor. A combined nut and bearing block 3 is carried by the plate 2 substantially centrally thereof adjacent a central opening 4 in the plate.

A movable carriage generally indicated at 5 is mounted for movement longitudinally of the table 1 on the carriage end B thereof, and the carriage preferably includes a chassis 6 provided with wheels 7, riding on rails 8, which may be the side angle members of the table 1. An electric motor 9 is mounted on framework 10, carried by the chassis 6., and

the operation of the motor is preferably con trolled by a controller 11.

The pulley 12 on the end of the motor shaft drives the wheel 13 through the medium of the belt 14. The wheel 13 is mounted on the end of a shaft 15 journal'led in the gear reduction case 16; and through a series of gears in the gear case the shaft 15 drives the carriage power shaft 17 whose axis extends in a direction longitudinal ofthe table 1, theaxis of the shaft 17 being aligned with the openmg 4 in the plate 2 and with the central bore 1-8 in the nut and bearing block 3.

A helical pattern 19 is coupled at 20 with one end of the shaft 17. The helical pattern 19 includes a shaft portion 21 and a helical thread portion 22. The outer end .23 of the shaft portion 21 is normally journalled .in the longitudinal bore 18 of the block 3, and the helical thread portion 22 of the pattern 19 extends spirally through the thread portion 24 of the block 3, as shown in Fig. 1.

Rotation of the motor 9 in one direction causes rotation of the shaft 17 in the direction shown by the arrow in Fig. 2, which causes the pattern to be irotatably threaded through the stationary nut block3 in a [direction toward the table flask end A, the carriage 5 meanwhile advancing toward the plate '2, as shown by arrows in Fig. 2. Rotation of the motor 9 in the other direction causes the shaft 17 to rotate in a reverse direction and rotatably move or thread the pattern 19 through the nut 3 in a direction toward the table carriage end B, the carriage 5 meanwhile moving away from the plate 2 as shown by the arrows in Fig. 3..

hen the motor 9 is stopped, the carriage 5 is stationary. However, the carriage and pattern are urged to move in a direction toward the plate 2 by a counter-weight .25 acting through .a cable 26 assing over a pulley 27 mounted on the ta le 1, .an end of the cable '26 being attached .to the chassis 6 of the device 5. Thus the counter-weight normally urges the forward face 28 of the pattern helical thread portion 22 to bear against the corresponding face .of the thread portion 2a of the nut block 3, for a purpose that will be hereinafter described.

The flask end A of the table 1 extending from the face of the plate 2 opposite the operating way for the carriage 5 constitutes a flask platform.

The improved apparatus also includes a four-sided flask generally indicated at 29 which is removably mounted on the table 1. and includes a bottom wall 30, two side walls 31, and an end wall 32. The flask 29 is also provided with a removable top wall .33 which when clamped to the flask 29 after the flask has been filled with rammed sand provides a flve-sided flask with one open end.

The flask 29 is positioned on the flask end A of the table 1, so that the plate 2 forms the sixth or closing end wall of the flask and sand rammed within the same is confined therein.

A clamping member 34 pivotally mounted at 35 to the table 1 clamps the flask 29 against the plate 2. Adjustable clamping members 36, mounted on L-shaped bars 37, which are pivoted at 38 at each side of the flask end A of the table 1, provide means for clamping the top wall 33 to the flask when the flask 29 is clamped against the plate 2 by the clamping member 34.

The flask 29 likewise preferably includes a removable end block 39 and wedge member 40 for purposes which will be hereinafter described.

The helical pattern 19 is preferably machined with great accuracy from a metal shaft, and the machined surfaces of the shaft portion 21 and threaded portion 22 thereof are usually supplied with a lubricant, which may be graphite 41 contained in a box 42 carried by the carriage side B of the plate 2 as well shown in Figs. 1, 2, and 3 for a purpose that will be hereinafter described.

The operation of the improved apparatus is as follows A four-sided flask 29, such as shown in Fig. 6 clamped by the clamp 34 against the plate 2 as shown in Fig. 1, the carriage 5 and pattern 19 being positioned as shown in Fig. 1. The block 40 is positioned in the flask adjacent the end wall 32, and the removable end block 39 is then placed in the flask adj acent the block 40. The removable end block 39 preferably is provided with a central bore 43 which is filled with sand prior to being placed in the flask.

Mold sand 44 is then introduced into the flask and rammed therein until the rammed sand has the desired uniform density throughout. The sand is then levelled off whereupon the top flask wall 33 is placed in the position shown in Figs. 1, 2 and 3 and the clamps 36 are adjusted to clamp the top wall to the flask and maintain the rammed sand 44 confined therein. Prior to clamping the top wall 33 to the flask, vents 45 are provided in the usual manner extending to the central region of the rammed sand as shown in Figs. 2 and 3.

T he carriage motor 9 is then started so as to rotate the shaft 17 in the direction shown by the arrow in Fig. 2, and rotation of the pattern 19 by virtue of the threaded connection between the th cards 22 thereof and the thread 24 in the nut block 3 causes the pattern to move rotatably through the block into the rammed sand until it has penetrated the same the desired distance which may be gauged by the indicator 46 on the carriage, and the scale 4? on the track 8. As the threaded. pattern 19 screws into the rammed sand, the sand is displaced so as to increase the density thereof at and adjacent the surface thereof contacting with the pattern which becomes the surface of the mold cavity.

After the pattern has penetrated the rammed sand to a desired depth, at which time the nose or end 23 thereof partially enters the sand in the bore 43 of the block 39 as shown in Fig. 3, further advancing movement of the pattern is stopped. The motor 9 is then reversed so as to rotate the pattern in the opposite direction, as shown in Fig. 3, and by reason. of its threaded connection with the nut 3, the pattern screws out of the mold cavity which has been formed in the rammed sand until the position of the pattern shown in Fig. 1 has been reached.

The clamps 36 are then loosened and the top wall 33 is taken off, whereupon the flask is removed endwise from the flask end A of the table 1, and placed at a mold finishing station.

The blocks 39 and 40 are then removed and replaced by a baked gate block 48 as shown in Fig. 4, which communicates at 49 with the enlarged or finished end 50 of the mold cavity 51 formed in the rammed sand 44. The gate block 43 is preferably held in position by ad ditional filler sand 52 as shown in Fig. 4.

A suitable core 53 is introduced in the core print formed in the sand by the nut and bearing block 3, and is clamped to the flask by suitable clamping means 54.

The fl skis now ready for pouring and may be transferred to the foundry pouring floor, at which place molten metal is poured into the pouring sprue of the gate block 48 to fill the mold cavity. The casting is then permitted to cool, is shaken out, and the gates and risers are removed. The necessary sand blasting, grinding, chipping, annealing, final finishing and straightening operations are then performed upon the casting to form the finished cast steel helical worm 56, shown in Fig. 5.

Although the operation of ramming the sand into the flask 29 has been described herein as being performed after the flask is clamped to the plate 3, for production purposes the fl-ask may be filled with rammed sand at a filling station whereupon the filled flask may be brought to the flask end A of the table 1 and moved longitudinally along the table 1 so that the projecting nose 23 of the pattern 19 axially enters the same.

Cast steel helical worms of any desired length may be cast by the improved apparatus simply by gauging the depth of penetration of the pattern 19 into the rammed sand. Moreover, cast steel helical worms of various diameters having one or more threads may be made by the improved apparatus simply by utilizing a pattern 19 of the desired size and shape and its corresponding cooperating nut and bearing block 3.

lVhen the pattern 19 is passed through a lubricant such as graphite 41, the surface of the, pattern is covered with the lubricant which later coats, smooths and formsa dense mold cavity surface, which will not be washed away by hot metal poured therein, and which resists erosion of hot metal. thus insuring the production of substantially perfect castings. For these reasons, the costs for cleaning cast ingsniade in molds produced by the improved apparatus are very low. It has been found that the present discoveries enables the molding cost of helical articles to be reduced three hundred to four hundred percent below prior practice costs.

The improved apparatus may likewise be' used in forming molds for helical articles in which the thread portion adjacent one end of the article has a greater thickness than at the other end thereof. When it is desired to produce such a casting, a pattern such as shown in Fig. 7 is utilized from which the normal thread 22 projects, the rear portion of the pattern having its thread thickened at 28 by adding metal to the rearward surface of the same. In constructing the pattern. 19 shown in Fig. 7, the forward surface 28 of the helical thread 22 has a constant lead which will constantly abut the thread recess 2a in the nut block 3, carried by the plate 2, during movement of the pattern in either direction through the nut block.

This contact between the forward helical surface 28 and the corresponding surface of the nut block thread 24 is maintained because the counter-weight 25 normally urges the pattern 19' to move in a direction axially to ward the flask end A of the table 1; so that there is no tendency to displace the pattern longitudinally without an accompanying rotary motion when entering or leaving rammed sand in a flask. Thus the following portions of the thread 22 will correctly track the leading portions thereof as the pattern forms a helical mold cavity or is withdrawn from the same.

Operation of the pattern in this manner may be further insured by utilizing mechanism such as shown in Figs. 7 and 8 which may be substituted for or form a part of the lubricant containing box 42, and which includes a housing 57 provided with aligning rollers 58 contacting with the circumferential surface of the thread 22 to form a bearing for the pattern-19 so as to decrease wear in the internal bore of the nut block 3.

Forward thrust of the pattern is resisted by rollers 59 carried by the housing 57 and contacting with the forward surface 28 of the thread 22, while rearward thrust of the pattern is absorbed by rollers 60 likewise carried by the housing 57 and contacting with the rear surface 28 of the pattern 19.

When portions of the thread are thickened as shown in Figs. 7 and 8, the rollers 60 must be yieldingly mounted at 61 to compensate for the thickened thread portions as the pat-.

those skilled in the art for rotatably moving the pattern through the nut block into and out of rammed sand in the flask.

Moreover, it is not intended to limit the scope of the invention to the making of molds from beginning to end on the flask end A of the table 1, because it is clear that certain of the mold making operations may be performed at other stations in a foundry.

Nor is it intended to limit the scope of the invention to the particular clamps, patterns, or nuts and bearing blocks shownand described herein, since the size and shape of the same must be varied according to the size and shape of castings desired to be produced.

we claim r 1. Apparatus for making molds for helical articles including a table,a five-sided flask provided with a bottom wall resting on the table adapted to contain rammed sand, said flask being removable and being provided with an open end, a plate mounted on the table forming a wall for said open end of the flask, means for clamping the flask to said plate, a helical pattern, nut means for the pattern, and longitudinally movable means for rotatably moving the pattern through the nut and plate into and out of rammed sand in the flask. v

2. Apparatus for making molds for helical articles including a table, a five-sided flask provided with a bottom wall resting on the table adapted to contain rammed sand, said flask being removable and being provided with an open end, one of the flask walls being removable, a plate mounted on the table forming a wall for said open end of the flask, means for clamping the flask to said plate, a helical pattern, nut means-for the pattern carried by the plate, and longitudinally movable means for rotatably moving get the pattern through the nut into and out of rammed sand in the flask.

8. Apparatus for making molds for helical articles including a table, a five-sided flask adapted to contain rammed sand removably mounted on the table, said flask including a bottom wall, two side walls, and one. end wall, a removable top wall for the flask, means for clamping the top wall to the flask, a plate mounted on the table forming the other end wall of the flask, means for clamping the flask to said plate, a helical pattern, nut means for the pattern carried by the plate, and longitudinally movable means for rotatably moving the pattern through the nut into and out of rammed sand in the flask.

4. Apparatus for making molds for helitill cal articles including a table, a five-sided flask provided with a bottom Wall resting on the table adapted to contain rammed sand, said flask being removable and being provided with an open end, a plate mounted on the table forming a wall for said open end of the flask, means for clamping the flask to said plate, a helical pattern, nut means for the pattern, longitudinally movable means for rotatably moving the pattern through the nut and plate into and out of rammed sand in the flask, and means for normally urging movement of the pattern axially toward the flask.

Apparatus for making molds for helical articles including a table, a iivesided flask provided with a bottom wall resting on the table adapted to contain rammed sand, sa d it k being removable and being provided an ab an open end, a plate mounted on the table forming a wall for said open end of the iask, means for clamping the flask to said plate, a helical pattern, nut means for the pattern, longitudinally movable means tor i'otatably moving the pattern through the nut into and. out oi? rammed sand in the flask, and means for aiplying a lubricant to the surface of ti e pattern as it rotatably moves into the rammed sand in the flask.

(.3. Apparatus for making molds for helical arti l including a table, a five-sided ask provided with a bottom wall resting on c table adapted to contain rammed sand, said flask being removable and being provided with an open end, a plate mounted on the table forming a wall for said open to said plate, means for clamping the to said table, a helical pattern, nut means for the pattern, and longitudinally movable means for rotatably moving the pattern through the nut into and out of rammed sand in the flask.

I. apparatus for making molds for helical articles including a table, a five-sided flask provided with a bottom wall resting 011 the table adapted to contain rammed sand, said flask being removable and being provided with an open end, a plate mounted on the table forming a wall for said open end of the flask, means "for clamping the flask to said plate, a helical pattern, nut means for the pattern, longitudinallymovable means for rotatably moving the pattern through the nut and plate into and out of rammed sand in the flask, and roller thrust resisting means for guiding the pattern as it rotates through the nut.

ti. Apparatus for making molds for helical articles including a table, a live-sided flask provided with a bottom wall resting on the table adapted to contain rammed sand, said flask being removable and being provided with an open end, a plate mounted on the table forming a wall for said open end of the end of the flask, means for clamping the flask, means for clamping the flask to said plate, a helically threaded pattern, stationary nut means for the pattern, and longi tudinally movable means for rotating the pat tern to move the pattern through the stationary nut and plate into and out of rammed sand in the flask.

9. Apparatus for making molds for helical articles including a table, a four-sided flask adapted to contain rammed sand removably mounted on the table including one bottom Wall, two side walls, and one end Wall, a plate rigidly mounted on the table forming the other end Wall of the flask, means for clamping the flask against the plate, a removable top wall for the flask, means for clamping the top wall to the flask, a helical pattern, a c0m bined nut and bearing block for the pattern carried by the plate, longitudinally movable means for rotatably moving the pattern through said nut into and out of rammed sand in the flask, and means for normally urging movementoi the pattern axially toward the flask.

10. Apparatus tor making molds for helical articles including a table, a five-sided flask provided with a bottom Wall resting on the table adapted to contain rammed sand, said flask being removable and being provided with an open end, a plate mounted on the table forming a wall for said open end of the flask, means for clamping the flask to said plate, a pattern provided with a helically arranged thread having a varying thickness, nut means for the pattern, and longitudinally movable means for rotatably moving the pattern through the nut and plate into and out of rammed sand in the flask.

In testimony that We claim the above, We have hereunto subscribed our names.

CHARLES E. NORDFELDT. WALTER J. AHLQUIST. IRWIN M. EMERY.

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