US2775015A - Control apparatus for extrusion presses and the like - Google Patents

Description

Dec. 25, 1955 i C. F. E@ 2,775,015

CONTROL AFFRTUS FOR EXTRUSION PRESSES AND THE LIKE Filed May 20, 1952 2 Shqqts-Sheet 1 CLARENCE F. ERB

Dec. 25, 1956 c. F. ERB 2,775,015

CONTROL APPARATUS FOR ExTRUsIoN PRESSES AND THE LIKE Filed may 2o, 1952 2 sheets-sheet 2 INVENTOR CLARENCE F. ERB

BY mf@ ATTORNEY United Sttes Patent *O CONTROL APPARATUS FOR EXTRUSION PRESSES AND THE LIKE Clarence F. Erb, Youngstown, Ghia Application May 20, 1952, Serial No. 288,888

4 Claims. (Cl. 25--16) The present invention relates to extrusion apparatus, and more particularly to apparatus for regulating and controlling the movement of extrusion machines of the type commonly used in forming an extruded article from a liquid or semi-liquid charge, as for example in the forming of clay drainage tile or brick.

The present invention has as its ultimate object the provision of apparatus for use on extrusion apparatus of the type utilizing a compressible iluid operating medium whereby operation of the extrusion apparatus may be subjected to accurate 'and instantaneously responsive control.

More particularly, it is an object of the present inven-v tion to provide apparatustfor use with steamor air-operated extrusion press apparatus and the like whereby movement of the press apparatus may be accurately and positively controlled and regulated independently of the steam or air pressure acting within the press apparatus.-

Heretofore it has been common practice to control the operation of steam or air actuated presses by merely interrupting and/ or'bleeding off from the actuating cylinder the compressed steam or air, but this method has been found to be not only highly wasteful of the air or steam utilized,.but inaccurate and subject to time-to-time variations due to the inherent tendency of the steam or air to expand even after thesupply thereof has been cut olf from the actuating cylinder. This latter eifect is particularly objectionable'where, as in the extrusion of clay tiles and the like, the extruded charge may varyfrom time .to

time in consistency.

A further object of the invention is the provision of control apparatus for use with steamor air-operated extrusion press apparatus utilizing a control cylinder and an incompressible control fluid medium whereby movement of the main airorsteamoperated cylinder may be accurately regulated and controlled by controlling the flow of the incompressible fluid from one end to the other-of the control cylinder. And the present invention contemplates controlling the flow of the incompressible iluid either independently of or in conjun-ction with the control of the principal compressible operating fluid.

Yet another object of thek present yinvention is the provision of apparatus for the purpose and having the characteristics enumeratediabove which may be readily and inexpensively incorporated into steamor air-operated exfor controlling the movement of the extrusion ram; and

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Figure 2 is an enlarged fragmentary section View of the apparatus of Figure 1 showing pertinent details of the construction and installation of my control apparatus.

Referring initially to Figure 1, the reference numeral 10 designates a vertically oriented funnel-like container or mud cylinder of a clay extrusion press which container conventionally comprises a cylinder portion 11, an inwardly converging portion 12 and an orifice 13 shaped and dimensioned to conform to the outer peripheral outline of the product to be extruded, which in the present illustration may be a tubular drainage tile 14. In accordance with known construction the orifice 13 may -be provided at its lower end portion with a bell-shaped or flared portion 15 which is usable in a manner to be later described in forming a similar flared end opening 16 in the tile 14 whereby a plurality of such tiles may be telescopically interconnected to form a longitudinally extending substantially continuous tubular conduit. Positioned centrally within the oriiice 13 is a cylindrical mandrel 17 which is carried in the container 10 by means of a plurality of radially extending webs 18. And it will be observed that a clay mass or charge 19 which is compressed within the cylinder portion 10 will be extruded outwardly thereof between the concentric walls of the oriiice 13 and mandrel 17. The arrangement is of course such that the article 14 formed during an extrusion operation Will be propagated in a vertically downward direction whereby it may be most easily and adequately supported while in a Weak andrelatively fragile state.

To support the lower end ofthe article 14 during formation thereof a platen 2t) is conventionally provided which is adapted to engage the lower end of the article 14 as illustrated in Figure 1 and to retract longitudinally in guides 21 as the article is propagated downwardly. According to known principles of construction the supporting stem 22 for the platen 29 may be operatively connected to counterweights 23 or other suitable devices which urge the platen 20 upwardly with suicient force to support the dead weight of the extruded article 14, it being understood that'the clay, for example, in its extruded form has an extremely low tensile strength.

Other conventional elements of the illustrated extrusion apparatus include a ram 24 which is positioned in the cylinder 11 and adapted to express the clay charge 19 therefrom, and a large diameter power actuator 25, the piston member 26 of which is rigidly connected to the ram 24 by means of a suitable piston rod 27. In accordance with good engineering practice the cylinder member 28 of actuator 25 is rigidly interconnected with the container 1t? and this may be accomplished by means of a plurality of supports 29 spaced circumferentially about the cylinder 28 and container 10 and rigidly secured thereto.

For the purpose of the present invention the actuator 25 may be of the type adapted for operation by any compressible fluid, such as steam or air for example, but it will be understood that steam is commonly used as a prime source of power where clay articles are extruded since it is usually necessary in such operations to provide a steam supply for other purposes, and the same may thus be advantageously and leconomically used for operating the extrusion press'. In the present illustration uid conduits 30 and 31 are provided at each end of the actuator 25 whereby a suitable source, not shown, of steam or other compressible liuid may be selectively connected to either end of the cylinder 28 to cause the piston 26 and ram 24 to move upwardly or downwardly as desired.

In a conventional tile extruding operation a bell-shaped mandrel section or plug 32 is positioned in the ared open end 15 of the container 10 whereby upon subsequent downward movement of the ram 24 the clay charge 19 is forced into a bell-shaped annular space between the end portion and the plug 32 to deline a flared lower end portion 16 of the article 14. By means of visual detection or automatic signal means, not shown, a machine operator is informed as :to vwhen the llared end yportion 16 has been completely formed, whereupon downward movement of the ram 24 is stopped and the plug 32 removed. A simplied arrangement for positioning and removing the plug 32 is illustrated in Figure l and comprises a pivotally secured mounting member 33 to the outer end portion of which the plug 32 is secured. A la-tch 34 mounted adjacent the flared portion 15 of the container lil is operative to engage the end of the mounting member 33 to retain the plug 32 properly positioned within the flared portion 15, and` it will be understood that the latch 34 may be readily disengaged when necessary 4to permit the plug 32 to swing into an inoperative position as illustrated.

After the flared end portion 16 is formed as above stated the ram 24 is caused to continue in its downward movement whereby to extrude between the mandrel 17 and orifice 13 a Cylindrical tubular article 14. An article of any desired length may be formed, within, of course, the capacity ot the apparatus, by stopping downward movement of the ram 24 at an appropriate time and severing the formed tubular portion from the charge 19.

Heretofore the downward movement of the ram 24 has been controlled by admitting and shutting otf the flow of steam or other compressible fluid to the actuator and/ or by bleeding oit to the a-tmosphere all or a large portion of the compressed fluid contained therein. Thus, for example, before removing the plug 32 after forming a ared end portion le of a tubular article it is rst necessary to remove all or substantially all of the downward pressure upon the clay charge 19, and this has been accomplished in the past by the wasteful but obvious expedient of bleeding all pressure from the upper end of the actuator 25. To continue te extrusion operation it is lirst necessary to rell the cylinder 28 with pressure Huid. To end the operation after an article 1.4 of predetermined length has been formed it is again necessary to shut oft the supply of steam and bleed olf the pressure. It is not possible, however, even though the 'steam supply is shut ot, to bleed ofi all pressure instantaneously and hence a certain portion of the charge 19 is expressed from the apparatus even after the same has been deenergized The amount of charged expressed from the apparatus after deenergization is quite variable, depending upon such factors as clay consistency and steam pressure, and accordingly this amount is not capable of accurate estimation and corrective compensation, even by an operator of long experience. Hence the articles produced are at best non-uniform in length, and in many instances wholly unsuitable for commercial sale and use.

By my invention I eliminate the above elements of waste and inaccuracy by mounting at the upper end of the actuator 25 a second actuator 35 by means of which I may accurately control the movement of the ram 24 and eliminate bleeding o of the steam pressure in actuator 25 during the intermediate step of forming the flared lower end 16 of the tubular article 14.

As illustrated particularly in Figure 2 actuator 35 cornprises a conventional hydraulic cylinder assembly having a cylinder part 36 and a piston part 37. The cylinder part 36 is, in accordance with the principles of the invention, secured to the actuator 35, and for this purpose I have provided a mounting platform 3S comprisinga plurality of legs 39 and a box-like platform member 40, which last mentioned members 39 and 40 are rigidly secured to the upper end of the cylinder 28 by means of a plurality of bolts 41, for example. Loosely received within the boxlke platform member 40 is a bearing block 42 having a concave spherical bearing surface 43 therein and a centrally disposed aperture 44 which is substantially aligned with a similar aperture 45 providedin the lower surface of the platform member 4G. The bearing block 42 is retained within the box-like platform 4t? by means of a ring 46 which is secured to the upper open end of the member 4t? in the manner indicated in Figure 2. The arrangement is such, however, that the bearing block 42 is adapted to have limited lateral sliding movement within the confines of the member 40.

Received in the member 4b and adapted for mating bearing engagement with the bearing block 42 is a second bearing block 47 having a large central aperture therein substantially aligned with the apertures 44 and 45. The second bearing block 47 is rigidly secured by means of bolts 48 to the cylinder member 36 of actuator 35, the arrangement being such that the cylinder 36 is normally vertically oriented and axially aligned with the actuator 25. Mounting inaccuracies are of course compensated for by a limited universal movement of the bearing blocks 42 and 47 so that the cylinders 36 and 28 are at all times properly oriented and aligned.

In accordance with the teachings of my invention the piston rod 49 of actuator 35 extends downwardly thereof through apertures 44 and 45 and is rigidly connected to the piston 26 of the steam actuator 25. Thus, I propose to control and regulate the movement of the piston 26 and extruding ram 24 under pressure of steam or other compressible gas in the cylinder 28 by providing an incompressible hydraulic fluid in the actuator 35 and suitable uidfcircuit associated therewith whereby the movement of piston 37 may be subjected to positive and responsive control by a machine operator. In the illustrated embodiment of the invention I have provided a lluid conduit 50which is connected to each end of the cylinder 36 so as to provide a path for the circulation of fluid from oneend to the other of the actuator 35 as the piston part 37 thereof moves in response to movement of `the extruding ram 24. Thus, for regulating the speed of movement of the piston 37 I may provide an adjustable gate valve 51 to partially block off the conduit 50 and thereby impede the flow of lluid from one end to the other of the cylinder and accordingly impede movement of the piston 37. With this arrangement the speed at which the tubular clay article 14 is expressed from the container 1t) ymay be controlled independently of the steam pressure provided in cylinder 28 and independently of the consistency of the clay charge 19. And it will be further understood that the effect of variations of these last mentioned factors upon the extruding operation will be minimized to a substantial extent whenever the valve 51 is adjusted so as to at least partially block oft the conduit 50.

As heretofore mentioned, the extruded clay article 14 is practically devoid of tensile strength until tired or otherwise further treated, and accordingly it is desirable to substantially slow down the speed of extrusion as the operation nears completion so that there will be no sudden stop at the end of the operation which would be likely to cause the article 14 to break olf. This is true even though the upwardly urged support platen 20 is provided, since if the apparatus is suddenly stopped in its downward motion the inertia of the platen 20 tends to keep the same moving downwardly whereby support is temporarily removed from the article 14. Thus, for the above purpose I connect a solenoid operated valve 52 into the conduit 50, which valve 52 is provided with suitable adjustable means, conventionally illustratedvat 53 as a stud and adjusting nut, forlimiting the closing vmovement of the valve to some position vwherein the conduit 50 is not completely blocked, but 'is impeded to a greater extent than is provided by the regulating valve 51. Valve 52 may be energized by a suitable electrical circuit including in the present illustration a limit switch 54 and relay 55. And while the limit switch `is shown as being actuated by an operator56 mounted on `the platen 20, it will be understood that any" othervarrangement will bev wholly satisfactory. For example, I may provide for the switch 54 to' be operated by a member, not shown, which is mounted directly on movable parts of the actuators or 35.

After a predetermined final length of clay has been expressed from the container 10 it is desirable to bring the ram 24 to a complete and substantially immediate stop, and in accordance with the present invention this may be accomplished by preventing further circulation of hydraulic tluid through the conduit 50. A normally fully open solenoid operated valve 57 is provided for this purpose, which valve is operative when energized to completely close o the conduit S0 and, of course, further movement of the piston 37 is thereby prevented. Suitable limit switch means 57, arranged to be operated after the extruded article 14 has reached a predetermined length, may be provided to energize the valve 56 through the intermediary of a switching relay 58.

In addition to the final stop limit switch 57 l have provided additional means for stopping downward movement of the ram for emergency purposes, for example, or to remove the mandrel plug 32, and in the illustration this last mentioned means comprises a normally open switch 59 of the push button type, for example.

Normally a fast and unimpeded retraction of the ram 24 is desirable to save time in recharging the container l0 with clay and where such is the case it is both unnecessary and undesirable to restrict the movement of piston 37 as the same moves from the bottom to the top of the actuator 35. Accordingly I have connected a second conduit member 6@ to each end of the cylinder 28 and have interposed a check valve 61 intermediate the ends of the conduit whereby a relatively unimpeded flow of Huid from the upper to the lower end of cylinder 28 is permitted regardless of the adjusted settings or energized condition of lthe control valves 51, 52 and 56. The conduit 60 is, of course, completely blocked off to passage of fluid from the lower to the upper end of cylinder 28 and downward movement of the piston 37 and ram 24 may be controlled entirely by valves 51, 52 and 56.

My apparatus finds particularly advantageous application in the art of extruding clay tiles and the like as suggested in the foregoing description. I have provided a means of accurately and responsively controlling the movement of the extruding ram of a steamor compressed air-operated press whereas heretofore such presses have been incapable of accurately controlled operation due to the inherent tendency of the compressible actuating uid to expand and further move the extruding ram even after the source of Huid has been disconnected from the actuating cylinder. This etect is particularly noticeable and detrimental where a semi-liquid substance such as clay is being extruded and where the substance and/ or operating l'luid pressure is subject to wide and unpredictable time-to-time variations.

A further great advantage of my apparatus accrues where, as in the present illustration, the extruding ram must be stopped intermediate the initiation and completion of an extmding operation. Thus, in the past it has been necessary to bleed ofi the lluid pressure from the main actuating cylinder in order to stop the ram and relieve the extruding pressure from the charge. A serious loss of efficiency results from this operation since the main operating cylinders of presses of this type are often in the order of three to four feet in diameter, and the bleeding ott of high pressure compressible operating uid represents a substantial loss.

The improved operating efficiency of my apparatus becomes of greater importance where articles of small cross section are extruded and hence several articles may be formed from a single charge of clay or other substance. By the present teachings it is merely necessary to energize the stop valve 56 one or more times for each article extruded, depending of course on the nature ot the article, and the operating cylinder 28 is not bled of its fluid pressure until the entire charge is exhausted. This is contrasted to the heretofore known arrangement where thecylinder `28 is exhausted one or more times for each article.

In designing my present apparatus I' have taken into consideration the fact that extrusion apparatus of the nature under consideration is quite costly and have therefore provided an arrangement whereby the existing press installations may be readily and inexpensively provided with a package type control unit which will adapt the 'apparatus for operation in the manner hereinbefore described. Of course, the control apparatus may also be readily provided as an integral part of a new installation.

Having thus described a preferred embodiment of the invention, what I claim 'as new and desire to secure by Letters Patent is:

l. In combination with an extrusion press of the type having a ram, a main iuid cylinder actuator adapted for operation by a compressible iluid, said main actuator having a movable piston member, and rigid means connecting said ram with said piston member; a hydraulic actuator having a piston anda cylinder one of which is a fixed member and the other of which is a movable member, means mounting said ixed member in rigid relation to said main actuator, means interconnecting said piston member and said movable member whereby movement of said piston member in a predetermined extrud-ing direction causes related movement of said movable member relative to said xed member, conduit means communicating with andrforming a closed circuit between opposite ends of said cylinder, fast acting valvemeans in said conduit means for preventing the flow of fluid from one end to the other of said cylinder whereby to quickly stop the movement of said piston in said cylinder, a second conduit member communicating with opposite ends of said cylinder, and a check valve in said conduit means oriented therein in such a manner that when said ram and movable member move in said predetermined direction uid in said cylinder is caused to circulate through said valve means and when said movable member moves in an opposite direction uid in said cylinder may circulate from one end to the other of said cylinder through said check valve independently of said valve means.

2. In combination with 4an extrusion press of the type having a ram, a main fluid cylinder actuator adapted for operation by a compressible iluid, said main actuator having a movable piston member, vand rigid means interconnecting said ram with said piston member; a hydraulic actuator interconnected with said piston member, conduit means interconnecting and forming a closed circuit between opposite ends of said hydraulic actuator, valve means in said conduit means operative to control the flow of fluid from one end to the other of said hydraulic actuator, said valve means including means to prevent any uid ow in said conduit whereby said actuators may be rendered immovable despite continued application of compressible iluid pressure to said main actuator, said valve means further including a slow down valve operative when closed to partially restrict said conduit means, and means operative during an extruding operation of said press to close first said slow down valve and second said means to prevent any iluid ow in said conduit whereby said piston member and ram may be caused to rst slow down and then to stop despite continued and substantially unvaried application of compressible fluid pressure to said main actuator.

3. l'n combination with an extrusion press of the type having a ram, a main uid cylinder actuator adapted for operation by a compressible iluid, said actuator having a movable piston member, and rigid means interconnecting said ram and said piston member; a hydraulic actuator having a piston and a cylinder, means mounting said cylinder in rigid relation to said main actuator substantially in alignment with said rigid means, a connecting rod rigidly interconnecting said piston and said pis- .i ton member, conduit'fmeans communicating with and forming a closed fluid circuit betweenv opposite ends :of-said cylinder, independently operative valve means in saidconduit means for controlling the flow of uid from one end to the other of said cylinder whereby to -control the movement vof said piston in saidcylinder,

lpress of the type utilized for extruding elongated clay and like articles of low tensile strength and having a container, a ram slidable in said container, a main uid cylinder actuator `adapted for operation by a compressible uid, said main actuator having a movable piston member, and rigid means connecting said ram with said piston member; a hydraulic actuator having Ia piston and cylinder one of which members is a movable member and the other of which member is a xed member, means mounting said Xed member in rigid relation to said main actuator, means interconnecting said piston member and said movable member whereby movement of said piston member in a predetermined direction causes related movement of said movable member relative to said ixedmember, conduit means communicating withand forming a closed .circuit 4between opposite ends 4of said cylinder, valve means for controlling the movement of said piston in said cylinder, said valve meansincluding a valve for adjustably restricting said conduit means, said xed member cornprising said cylinder and said movable member comprising said piston, means to mount said cylinder in fixed relation to said main actuator comprising a platform rigidly secured to said main actuator, a first bearing block slidably carried by said platform and having a spherical bearing surface thereon, a second bearing block rigidly secured to said cylinder and having a spherical bearing'surface thereon adapted for complementary engagement with said first mentioned bearing surface, said means interconnecting said piston member and said movable member comprising a piston rod rigidly secured to said piston and said piston member.

References Cited yin the tile of this patent UNITED STATES PATENTS 253,199 Good Feb. 7, 1882 450,201 Titus Apr. 14, 1891 452,202 Taylor et al. May 12, 1891 489,130 Melling Ian. 3, 1893 817,209 Williams Apr. 10, 1906 1,331,286 Simmonds Feb. 17, 1920 1,808,964 McClintock et al. June 9, 1931 2,326,498 Rodal Aug. 10, 1943

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