US2552930A - Extrusion of clay products - Google Patents

Description

y 1951 J. F. BOOTH ET AL 2,552,930

EXTRUSION OF CLAY PRODUCTS Filed Nov. 17, 1949 4 Sheets-Sheet ,3.- 2| Jal I3 [2 FIGJ.

66 vii FIGS.

y 5, 1951 J. F. BOOTH ET AL 2,552,930

EXTRUSION 0F CLAY PRODUCTS Filed Nov. 17, 1949 4 Sheets-Sheet 2 36 P777771 I y/ All a l I f 54 P I 53 m] 53 52 f i I 5 l I 5| 32 FIG. 2

Ir wenlor Attorney May 15, 1951 J. F. BOOTH ET AL sxwausxon 0F CLAY PRODUCTS 4 Sheets-Sheet 5 Filed NOV. 17, 1949 Attorney CUM;

May 15, 1951 J. F. BOOTH ET AL 2,552,930

EXTRUSION OF CLAY PRODUCTS Filed Nov. 17, 1949 4 Sheets-Sheet 41 Inventor Mw M Attorney Patented May 15, 1951 Ex'rRUsioN OF CLAY PRODUCTS John F. Booth and Rowland K. Smith, Hazlehead, near Sheffield, England Application November 17, 1949,, Serial No. 127,936 In Great Britain November 26, 1948 16 Claims.

This invention relates to the extrusion of clay products in machines of the type in which the clay is fed to the top of a cylinder and forced downwardly to an extrusion orifice by means of a worm.

One object of the invention is to provide for the feeding of clay to the cylinder in accordance with the rate at which clay is extruded. A further object is to maintain the clay in the cylinder substantially constant at the amount producing the greatest extrusion efiiciency. Yet another object is to provide for the feeding of a battery of machines from a common supply. Other objects will appear from the following description.

According to the present invention, the feed of clay to an extrusion cylinder is controlled by forming a substantially level surface on the body of clay to be extruded and varying the rate of feed of clay to the body in accordance with variations in the level of said surface, more clay being fed as the surface falls in response to extrusion so as to restore the level.

By substantially level is meant that the surface as a whole is flat, as quite distinct from the approximate vortex produced by the rotation of the clay; but in practice the surface is not and need not be truly flat, and minor variations from true flatness permit a sufiiciently sensitive and accurate control to be made.

It is generally convenient if .the fall in the surface below a predetermined level permits the feeding of more clay to the body, and the consequent rise to another predetermined level cuts off the feeding, the limits of rise and fall in the surface being kept within the greater amount of clay that would result in overloading the machine and the lesser amount of clay that would not adequately pack the extrusion worm.

In mechanism accordin to the invention, the substantially level surface is formed on the body of clay to be extruded by at least one arm adapted to be rotated about the axis of the cylinder, and the rate of feed of clay to thebojdy is varied in accordance with the movement of a feeler mem ber adapted to rise and fall in response to variation in the level of the surface.

The arm is preferably formed with an upstanding blade, the arm generally sweeping the clay to a level and the blade removing from the Wall of the cylinder the layer of clay forming there as a vestige of the vortex-like surface tendingto be produced by the rotation of the clay as a whole. Advantageously, more thanone arm and blade are used, the arms and bladesoonveniently being inclined so as to assist in urging the clay downwardly.

hydraulic or electrical means, or combinations of such means, serving to controlthe amount of clay fed to the cylinder, the clay being continuously fed in an amount equal to' the maximum requirement of the machine and the particular requirement at any moment being diverted to the machine in response to the action of the feeler member, the excess being returned to be rec, again. The feeler member is conveniently pivoted above the level of the surface in the cylinder. o I

The invention will now be described in greater detail, by way of example, with reference mine;

accompanying drawings in which Figure 1 is a diagramlillustr'ating the automane feeding of clay to a battery of four:

machines;

Figures 2 and 3 are a sectional elevation and plan, respectively, ofthe upper portion of one ,of the extrusion presses diagrammatically illustrated in Figure 1;

Figure 4 is side elevation, drawn to a smaller scale than Figures 2 and 3, showing thefeedin'g of clay to' the ho per of the press shown in Figures 2 and 3;

Figures 5 and 6 are, respectively, a front el'e vation and plan of part of the apparatuss'howh in Figure 4; i

Figure 7 is an elevation of the upper portion of an extrusion press showing a modified form of feed hopper; I H

Figure 8 is a diagram illustrating the control circuit of the apparatus shown in Figures 2 to 6; and

Figuref9 is a diagram illustratin the control circuit of the apparatus shown in Figure 7.

Referring first to Figure 1, a battery of four extrusion presses ll, l2, l3"an'd [4 are fed with clay from a common mixing pl'ant 1B,,the clay. being delivered from the mixing plant, IS in' shredded form (1. e., in relatively smallpieces or particles) on to a" main belt conveyor I! which delivers the clay to a chute l 8'f1eading to a feed conveyor l9 leading to thefour presses in succession. The clay is fed from the mixing plant I6 in an amount'at' leastequal to the maximum requirement of the four presses H to M and the particular amount required by each press is first plough being set to move over one quarter of the belt width, the next over one half of the width, the third over three quarters of the width and the last over the whole width. Each plough 22 thus normally sweeps into its chute a quarter of the clay fed by the conveyor belt l9.

The ploughs 22 are automatically moved into operative or inoperative position in accordance with the requirements of the presses, as will be described later, and any surplus of clay not swept off the belt l9 by the last plough is discharged into a chute 23 leading to a return conveyor 24 which, in turn, discharges into a return chute 26 leading back to the main conveyor H. The operator in charge of the mixing plant l6 regulates the supply of clay from the plant in accordance with the amount of scrap being returned by the conveyor 24.

A continuous feed of clay is thus provided to the battery of presses, each press automatically diverting from the conveyor l9 sufficient clay for its own needs. The manner of control of the clay feed to the individual presses will'now be described.

Referring to Figures 2 and 3, an extrusion worm 3| housed'in an extrusion cylinder 32 is driven by a bevel pinion 33 mounted on a drive shaft 34 and arranged in mesh with a bevel gear 36 secured to the shaft 37 of the worm 3|, the shaft 3'! being provided with an upper bearing in a bearing bracket 38 secured to an enlarged upper portion 39 of the cylinder 32 constituting a feed chamber, the bearing bracket 38 serving also to house bearings for the drive shaft 34.

Clay is fed into the feed chamber 39 from a feed hopper 4| by an' oscillating charger 42 pivoted at 43 and oscillated by a crank 44 and connecting rod 46, the crank being formed on a crankshaft 47 mounted in bearings 4:8 (see Figure 4) and driven continuously by motor and reduction gear (not shown). The charger 42 forces the clay through a grid 49 which serves to retain a plug of clay, constituting a seal, in the inlet of the chamber 39 thus allowing the space above the general level of the clay in the chamber 39- to be maintained under vacuum, the inlet of the chamber 39 being below the general level of the clay.

Within the chamber 39 the worm shaft 31 is provided with a series of inclined propelling blades serving to force the clay downwardly into the extrusion cylinder 32, and above the uppermost blade 5|, there is secured to the shaft 31 a pair of levelling arms 52 terminating in upstanding blades 53, the arms 52 sweeping the clay to a substantially level surface while the blades 53 remove'from the wall of the chamber any layer of clay forming there as a vestige of the vortex-like surface tending to form as a result of the rotation of the clay as a whole. The arms 52 and blades 53 are also inclined so as to assist in urging the clay downwardly. A deflector ring 54, formed from angle iron, is fixed to the chamber wall above the level of the blades 53 to deflect inwardly any clay spreading up the chamber wall.

Pivotally mounted in bearings 59 (see Figure 5) formed in the wall of the chamber 39 above the deflector ring 54 is a shaft 5'! secured to which is a pair of feelers 58 arranged on opposite sides of the shaft 31, the feelers being about two inches Wide and resting freely on the surface of the clay formed by the levelling arms 52 so as to rise and fall with variations in the level of the surface.

The movement of the feelers serves to operate a pneumatic servo-mechanism controlling the amount of clay fed to the hopper 4| in a manner which will now be described with particular reference to Figures 4, 5 and 6.

Secured to one end of the shaft 51 protruding from the chamber 39 is an arm 59 to the extremity of which is pivotally attached one end 6| of a telescopic valve-operating rod 6|, 62, arranged to actuate avalve 63, the two parts SI and 62 of the'rod being connected by a tension spring 64 (see Figure 8) serving as a safety device in case of excess movement of the feelers 59. The, valve 63 controls the supply of compressed air from a pressure line 65 to a double-acting pneumatic cylinder 66 controlling the operation of the plough 22 mentioned above with reference to Figure 1. The plough 22 is pivotally mounted at 61 on a framework 68, serving to support the conveyor |9 at a higher level than the feed hopper 4|, the free end of the plough being supported on a guide plate 69 by means of a projecting lip H. V The cylinder 66 is pivotally attachedat 12 to the framework 68 while its piston rod 13' is pivotally attached at "to the plough 22.

The valve 63 also controls the supply of compressed air to another double-acting cylinder 75 pivotally attached at H to a bracket '18 extending from the hopper 4|, its piston rod 19 being pivotally attached at 8| to a gate 82 pivotally mounted at 33 on the discharge end of the chute 2| immediately above the hopper 4|, the gate serving to retain a reserve of clay in the chute. The valve 63 and cylinders 66 and 16 are of knownconstruction and are generally indicated diagrammatically in Figure 8.

The apparatus described in this example, however, is intended for the manufacture of socketed pipes, the extrusion being interrupted as each pipe is formed and removed from the extrusion press. The feeding of clay, therefore, roughly coincides with the extrusion of each pipe.

As soon as extrusion is interrupted (or the feed to the hopper becomes excessive, therefore, the continued feeding of clay to the chamber 39 causes the levelling arms 58 to lift and move the valve 63 into reverse position (the valve being moved in this case through the tension in the spring 64), thus causing air from the pressure line to pass through an air line 87 to the closed ends of the cylinders 66 and T9 to cause the plough 22 to move into its inoperative position and the gate 32 to close. Whilst, in this example, the charger 42 operates continuously, therefore, the supply of clay to the hopper 4| is cut off and no clay is fed to the chamber 39. In the event that the levelling arms lift excessively, e. g. by a sudden increase in the feed of clay, the excess movement of the arm is allowed by increased extension of the spring 54, thus preventing damage to the valve 63.

Figure 7 shows an extrusion press in all respects similar to that described above except that the clay is forced through the grid 49 by a modified form of feed mechanism (indicated att|4 in Figure 1). In this case, the clay is delivered by the chute 2| directly to the inlet of a feed hopper 88 in which is rotatably mounted a feed worm 89 rotation of which forces the clay through the grid 49 into the chamber 39. The worm 89 is driven by bevel gearing 9|, 92 and belt gearing 93 from the drive shaft 34, and the feeding operation thus takes place only when the machine is extruding, the worm 89 stopping with the drive shaft 34.

In operation, as the clay is extruded from the cylinder 32 by the extrusion worm 3|, the general level of the clay in the chamber 39 falls, thus QiBSQiQSG causing the feelers 53 to pivot by gravity amp the ejriir 59 re operate the-va1ve -63 (the use scopic' rod GI, 62, beingfully closed-during this: movement), such-operation of the valve-admitting air from the pressure line-65 to' an air line 86' leading to the piston-rod ends ofbothcylinders 6B and 16 thus causing the ploug-h22 to move from its inoperative position (shown in chaindottedlines in Figured) intothe path of the clay on the conveyor 19, and the gate B2 to open as indicated bychain-dottedlinesin Figure 42 Clay is thus swept from the'con'veyo'r l-9- into=the-chute- 2| to replenish that allowed to flowintothe hop er H by the openingof the gate 82 Asthe clay falls'into thehopper 41, it is for'ced through" the grid 49 by the oscillating charger 42 into-the chamber 39- toreplenish theclay' extruded by thewarm 3i. The chute 2| is" inclined at a steep angle; say 45 to- 55 to allow the clay to slide freely down the chute,- and to-preserve a-substantially uniform coefiicientof'friction, the chut'e is formed from non-rustingmaterial, e. g, stainless steel. The chute is'also open-topped' to prevent possibility of jamming when a large quantity'o'f clay discharged by the plough 22. The upper (wider) end of the chute is enclosed, however, toallow oil mist to be sprayed in for lubrication purposes.

It will thus be seenthat while extrusion-continues, clay is automatically-fed'tothe hopper- 4| from the conveyor l9 and the chamber 39 is replenishedl The worm 3 I is' thus kept fully packedwithout excess height of clay in thechamber 39, and the rate of extrusion thus kept to its highest value for the particular type of machine;

The-apparatus in-this example isintended for manual-control, the drive shaft 34bell'lg operatedthrough a clutch 94- in response a control lever 96- (see-Figure 9). The clay feed is again controlled by pneumatic servo-mechanism operating inresponseto'the feelers 58, but the servo-mechanism is also responsive to the clutch control lever 96. The pneumatic mechanism is of" known construction and is diagrammatically representediri Figure 9.

As before, the shaft 51 carrying the feelers 5'8 isprovided' with an external arm 91- pivotally connected to atelescopic-pistonrod 98 arranged tooperate a valve 99 controlling the supply of air from a pressure line llll to the-cylinder 99 operating' the plough 22-. In addition tothe valve 99; however, a further valve I02 is operable by the clutch control lever 96 to direct air from-the pressure line II]! to a further cylinder I93 arranged tooperate the clutch 94; The valve l 02a1so controlsthe supply of air from thepressure line w l toa further cylinder I04 arranged inparallelwith the cylinder I03 and controllingtheposition of an abutment member I96 contained ine slotted member lll'l attachedto the piston rod I08 of the cylinder H94 and embracing the arm 91.

Assuming the apparatus to be stationary, extrusion is commencedby moving the control lever 96 (to the left in Figure 8) to operate the clutch 94, whereupon air is admitted to the closed ends of the cylinders I93 and E94 through an air line I99 thusengaging" the clutch 94 and moving the abutment member I96 clear of the'arm 91 to allow the feelers 58 to fall and operate the valve 99 which moves the plough 22 into operative position. With the abutment lllficlear ofhthearin 91; the feelers are free to" rise or? fall" and the operation of the valve SQ'is'thusdependention the level of the clay in the chamber 39;

When extrusion ceases (and with it rotation of the feed worm 89) by operation of the control lever: 96: (to-theright'in- -Eigur'e-9)-, air lsdi:

recte'd by the valve I02 through anair line Hi to the piston rod ends or the-cylinders |U3 and l 04 to de-clutchthe-drive shaft-34 and move the abutment member I06 into engagementwith the arm 9T 50- as tocause it to pivot and operate the valve 99 which thereupon admits air from the pressure'line llllto the closed end of the cylinder 66 through an air line H2, thus moving the plough 22 into its inoperative position.

the clutch 94 is disengaged, therefore, the feelers remain inactive.

Whilst the above examples have been described I with? reference to intermittent extrusion, it will be: understood that the invention is equally applicable to continuously extruding presses.

What we claim is:

1. Method of controlling the feed of stiff; clay to a vertical extrusion cylinder in which a body of clay is progressed downwardly, said method comprising feedingclay into the upper end of the body of clay, sweeping the free upper surface of:

the body by a clrcular'motion to bringit substantially level, feeling the level'to which the upper surface-has been brought, and varying the rate of feed' of clay in response tovariation in level of said surface.

2. Method as in claim 1, comprising: divert;- ing clay. from a continuous stream in granular form towards the cylinder in response to. a fall in the level of the surfacarestraining a; quantity of the diverted amount. externally of the cylinder on a rise of the level. above a predetermined amount, and releasingthe restrained quantity for immediate feed into the'cylinder on a fall in the:

level;

3.- Mechanism for controlling the feed of stiff: clay to a vertical extrusion cylinder, comprising:

at least one arm adapted to be rotatedabout: the.

axis'of the cylinder soas to form a substantially level surfaceon the body of clay in the cylinder, afeeler member adapted to rest on the surface? so as" to rise and fall in response to variation.- in the level of the surface, and means'for vary With the grid, and means to-force the clay from the hopper through the grid into the cylinder in the form of a plug to constitute a seal;

5. Mechanism as in claim 4, comprising an' oscillating charger as the meansfor forcing clay through the grid;

6. Mechanism as in claim 4, comprising a" rotatable worm as the means'for forcing clay through the grid.

of the arm is inclined so as to-assist inurging theclay downwards in the cylinder.

8. Mechanism for controlling the feed of; stiff adapted to rest on the surface soas to rise and fall in response tovariation in the level ofthe" surface, and means for varying the rate of feed of-c1ayto the body in accordance'with the rise When i. Mechanism as in'claim 3; wherein the blade or fall of the feeler member, more clay being fed as the feeler member falls and less clay being variation in the level of the surface, and means for varying the rate of feed of clay to the body in accordance with the rise or fall of the feeler member, more clay being fed as. the feeler member falls. and less clay being fed as the feeler member rises.

10. Mechanism for controlling the feed of stiff clay to a vertical extrusion cylinder comprising at least one arm adapted to be rotated about the axis of the cylinder so as to form a substantially level surface on the body of clay in the cylinder, a feeler member adapted to rest on the surface so as to rise and fall in response to variation in the level of the surface means for feeding clay towards the cylinder, and a servomechanism responsive to movement of the. feeler member and serving to control the amount of clay fed to the cylinder, by rendering the feed means alternately operative and inoperative.

11. Mechanism for controlling the feedof stiff clay to a vertical extrusion cylinder, comprising at least one arm adapted to be rotated about the axis of the cylinder so as to form a substantially level surface on the body of clay in the cylinder, a feeler member secured to a shaft pivotally mounted across the upper portion of the cylinder, the feeler member being arranged to rest on the surface so as to pivot said shaft in response to variation in the level of the surface, an operating arm secured to said shaft outside the cylinder, and a servo-mechanism responsive to movement of said operating arm serving to control the amount of clay fed to the cylinder.

12. Mechanism for controlling the feed of stiff clay to a vertical extrusion cylinder in which an extrusion Worm is mounted on a vertical rotatable shaft, comprising at least one arm secured to said rotatable shaft above the Worm so as to form a substantially level surface on the body of clay in the cylinder, a feeler member adapted to rest on the surface so as to rise and fall in response to variation in the level of the surface, a hopper feed leading to the cylinder, a feed worm rotatably mounted in the hopper and adapted to feed the clay into the cylinder, means for varying the rate of feed of clay to the hopper in accordance with the rise or fall of the feeler member, a clutch controlling the rotation of the extrusion worm and the feed worm, a servomechanism for operating the clutch, and means connecting said servo-mechanism to the feeler member to render that member inoperative when the clutch is disengaged.

13. Mechanism for controlling the feed of stiff clay to a vertical extrusion cylinder, comprising at least one arm adapted to be rotated about the axis of the cylinder so as to form a substantially level surface on the body of clay in the cylinder, a feeler member adapted to rest on the surface so as to rise and fall in response to variation in the level of the surface, a conveyor arranged to feed the clay in granular form continuously towards the cylinder, a hopperfeed leading to the cylinder, a chute leading from the conveyor to the hopper feed a plough movable across the conveyor and adapted to divert clay from the conveyor into the chute, a movable gate controlling the fiow of clay from the chute into the hopper feed, and a servo-mechanism responsive tomovement of the feeler member and adapted upon such movement simultaneously to operate the ploughand the gate, the closing of thegate restraining a quantity of clay available for im mediate feed into the cylinder upon subsequent opening of the gate. V

14. Mechanism for controlling the feedof stiff clay to a vertical extrusion cylinder, comprising at least one arm adapted to be rotated about the axis of the cylinder so as to form a substantially level surface on the body of clay in the cylinder,.-

a feeler member secured to a shaft pivotally mountedin the upper portion of the cylinder, the

feeler member being arranged to rest on the surface so as to pivot said shaft in response to varia-- tion in the level of the surface, an operating arm secured to said shaft outside the cylinder, an endless conveyor arranged to feed the clay continuously towards the cylinder, a hopper feed leading to the cylinder, a chute leading from the conveyor to the hopper feed, a plough movable across the conveyor and adapted to divert clay trol the movement of the gate, and a valve rcsponsive to movement of said operating arm and controlling the supply of compressed air to-both of said cylinders whereby the plough and the gate are operated simultaneously upon movement of the feeler member. a

15. Mechanism for controlling the clay to a vertical extrusion cylinder, comprising at least one arm adapted to be rotated about the axis of the cylinder so as to form a substantially level surface on the body of clay in the cylinder,;

an upstanding blade on said arm for removing from the wall of the cylinder any layer of clay tending to form there as a result of the rotation of the clay as a Whole, a feeler member adapted to rest on the surface so as to rise and fall in response to variation in the level of the surface, and means for varying the rate of feed of clay to the body in' accordance with the rise or fall of the feeler member, more clay being fed as the feeler member falls and less clay being fed as the feeler member rises.

l6. Mechanism as in claim 15, comprising a deflector ring secured to the cylinder wall above thelevel of the blade.

JOHN F. BOOTH. ROWLAND K. SMITH.

REFERENCES CITED The following referencesare of record in the file of this patent:

UNITED STATES PATENTS Bower Oct. 25, 1949 feed of stiff

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