US2338491A - Powdered material press and control - Google Patents

Description

J1 B. CUTLER APOWDERED MATERIAL PRESS AND CONTEUL Filed Jan. 2, 1941 z sheets-sheet i www / fil @y gig 1 nTToE/VEY Jan.*4, 1944. .1. B. cuTLER POWDERED MATERIL PRESS AND CONTROL Filed Jan'. 2, 1941 2 Sheets-Sheet 2 INVENTOR vLJQHN B. CUTLE:

ATTORNEY I Patented Jan. 4, .1944,

UNi'rEo vs'r.%\rr='.s PATENT;

OFFICE- POWDERED. MATERIAL PRESS AND CONTROL John B. Cutler. Haddon Heights, N. I., assigner 4 A to The Baldwin Locomotive Works, a corporation of Pennsylvania i' Application January z, 1941,'sma1 No. 312.782

11 claims. (c1. 1li-1s) This invention relates generally tol presses forforming products from powdered material and particularly to means for controlling both the density and size of pieces produced.

Products of powdered material are formed by lling a mold cavity with nely powdered metal or other material and then compressing the powder to a cohesive state by a plunger. Ma-

v following description of the accompanying. drawings in which:

Fig. 1 is a vertical section through a hydraulic v press embodying a portion of my improved apchines for this general purpose are very old but they have not been capable of producing products under large pressures withinprecision limits as to dimensions and/or density. The problem of providing a. machine capable vof 'sucht precision operation becomes especially dimcultwhen Ait is attempted to have the press produce the articles rapidly and particularly when the articles require exceptionally large compressive forming forces. My invention is particularly applicable to` powdered metals although other kinds and forms of loose materials maybe used and also in the preferred specific embodiment of the invention I employ a hydraulic press although certain features of my invention are applicable to mechanical presses as well.

It is an object of my invention to provide improved means for forming products .from loose material with a high degree of dimensional accuracy. It is also an object to provide improved means for controlling thedensity of the products, especially while maintaining the desired dimensional accuracy of the products.

A furtherv objectis to provide; an improved .press and control therefor` whereby precision operation is capable ofbeing obtained` under large compressive forces which with my improved apparatus may be upwards of 200,000 or 300,000 pounds. 1

[i further object is to provide improved means for accomplishing density and/or dimensional control automatically during operation of the equipment.

paratus;

Fig. 2 is a combined wiring and mechanical f stationary crossheadt. 'As is` usual in hydraulic presses a main cylinder t., formed in crosshead A t, supports a lling tank t from which oilor other suitable liquid under low pressure ows through a filling valve l, of well-known form and operates, to cylinder E during downward movement of a main ram t. If desired, a pair of additional rams and cylinders generally indicated at Qand l0 may beJ employed, all of the. rams being 'suitablyconnected to an upper movv able platen Il which is guided by the side columns 2 and 3. A lower movable platen l2 is y also guided by side columns 2 and 3 and ispmoved downwardly by a -ram and cylinder generally indicated at i3, .the cylinder being formed inv lower crosshead l. The ram is connected by a lower movable crosshead i4 to side rods I5 and iii which are connected to the piston I2; The platen l2 4is normally biased upwardly by one- -or more small constant pressure pushback Vrams and cylinders such as generally indicated .at l1.

A still further object is to provide a hydraulically operated press with .improved means for controlling the press operation so as to obtain the desired dimensional ,control over the products.

A further object is to provide an improvedl apparatus that is economical in operation and maintenance and is durable and rugged combined with a positive and yet sensitive operation so as toproduce products having Aa very substantial degree of uniform accuracy as to density and dimensions.

Other objects and advantages `will be more apparent those skilled in the art from the The press .structure so far described is of well-1 known oonstruction and hence further detailed description is not necessary.

To form a powdered product a diemold gen erally indicated at 20 isl positioned within a suitable recess in platen l2. This mold is speciically shown las having aninner annular wall 2| which specifically forms the mold cavity while an outer relatively thick annular band v22 is shrunk on to the die moldV 20. This operation causes the die 20 to be preloaded un- -der compression stress, thus preventing or minimizing expansion of. the die under load vand vthereby' maintaining a high degree of radial die Y mension of the product. The foregoing novel preshrunk die structure isV held in positionby a .sizeal'ld sizes. This operation, however.

The die shape may be such that it has a smooth periphery so as to form bushings or the like or it may have, gear teeth to form gears, etc. The plunger 24 is supported upon stationary crosshead I and has a vertical slot 25 through which a crosshead 26 extends for connection to platen I2 by rods 21 and 28. If the products such as 'I bushings, gears or the like require a coaxial hole a pin 29 may be removably threadedly secured to crosshead 26 and extend upwardly through stationary plunger 24 into die 2i. A movable compressing plunger 30, carried by upper platen Il, has the same conformation' as die 2l and also has a suitably vented central bore 3l to receive core pin 29.

To form a product, powdered metal or other material is poured inany usualmanner into the mold cavity around the core pin 29 and excess powder is swept oi! by a usual well-known sweeper arm on the usual-feed box. The powder remaining in the mold will be level with the top thereof. Platen II is then moved downwardly under hydraulic pressure to force plunger 35 into themold cavity. When the product is fully compressed the platen II is raised by supplying hydraulie pressure to the cylinderspace 33 beneath differential piston 8. 'I'he product is ejected by supplying rluid pressure to cylinder I3 thereby movingplaten I2 and its mold 25 downwardly over the product which rests on stationary plunger 24. It will be understood that during the compression stroke the increasing compressing pressure on the powdered metal causes the frlctional contact between the powdered metal and the mold wall to increase and this friction causes platen I2 to yield downwardly against the constant pressure pushback plungers and cylinders I1. This yielding of the platen I2 4under the foregoing friction load effects what is known as a floating mold action. This allows the frictional resistance to be less than if the mold re mains stationary. In my present invention I provide improved means adapted to variably cooperate with the floating action so as' to dimensionally control the products while at the same time obtaining complete freedom of operation of the oating action and also obtaining uniform density of products even though accompanied by the variable dimensional control.

. The foregoing cooperative relation is of such a character that I am able to employ therewith improved means for initiating and controlling the actuation of the dimensional control mechanism in response to the dimensions of products ejected from the press.

In many instances in the past it has' been proposed to control the dimensions of a product by employing presses having only a fixed stroke for the compressing plunger and then ,adjusting the depth of the mold whereby more powdered material could beadded to increase the axial dimension of the product. However, this involved disadvantages among which is that suc-A been accompanied by a variable density of the successive products because the density iinally obtained was dependent upon the volume of powdered metal and the xed strokeof the compressing plunger. In my improved arrangement the plunger 30 is adaptedto have a variable stroke controlled solely by AtheI density of the individual articles thereby allowing the density of the product to be substantially independent of the quantity of powdered metal within the mold. By utilizing this characteristic I am able to freely adjust the mold platen to obtain dimensional control without sacrifice of density control.

To obtain densication control I preferably employ means responsive to the actuating force applied to the plunger 30 specifically by determining the hydraulic pressure in cylinder 5. When this pressure reaches a predetermined value the supply of'hydraulic pressure is discontinued and the plunger 30 is returned upwardly. Hence, the plunger will continue downwardly until the main cylinder pressure reaches a predetermined densifying value, the stroke therefore not being of flxed length. One form of mechanism capable of accomplishing the foregoing densifying control is diagrammatically indicated in Fig. 1 wherein a postive displacement piston pump 35 of the reversible Hele-Shaw type is connected in a usual manner by pipes 36 to the cylinders 5, 3 and I0 and by pipes 431 to the pullback end 33 of cylinder 5 and by pipes 33 to the stripping cylinder I3. Usual valves to compensate for the differential fluid volume to the respective cylinders during up and down operations vof their rams are omitted for the sake of simplicity, although such devices are well-known in the art. When the platen Il is in its uppermost position its arm 39 holds a rod 40 and bell crank 4I in the position shown in Fig. 1 Whereby the usual pump control rod 42 shifts the pump substantially to its neutral position. To initiate the down stroke the operator manually rotates the bell crank in the counterclockwise direction until engaged and held by alatch 43. Such counterclockwise movement shifts the pump forwardly to discharge fluid through pipe 36 to the cylinders 5, 9 and III and to draw iiuid from the pipes 31 and 38. As the plunger engages `the powdered metal in mold 2i the pumppressure builds up in the main cylinders and when this pressure reaches a predetermined densifying value a piston 44 is moved against an adjustable spring 45'to release latch 43 whereupon a compression spring 45 shifts the pump through its `stern 42 to a reversing position so as to supply fluid through pipe 31 to the diierential cylinder end 33 and also through pipe 38 to the stripping cylinder I3 thereby. moving platen I2 downward- 1 y to eject the formed product from mold 2|. When the press returns to near its upper position it engages nut 40' to lift. rod 40 and return the pump to neutral. If desired, the press operations may 4be continuously repeated without stopping by employing any welll-known repeating cycle control. However, for purposes of my invention in regard to the densifying operation theabove single stroke operation will suffice.

has heretofore 50 and 5| and 'I'he dimensional control mechanisin comprises, in one speciiic form of the invention, a pair of wedge seat members Eiland 5I, Fig. 1, bolted or otherwise suitably secured to crosshead I4 and which, if necessary, may be suitably shimmed as indicated at 52. Wedge blocks 53 and 54 are interposed between ythe seats the under surface of crosshead I.

The wedges 68 and 54 are each provided with non-rotatable threaded shafts 55 and 56 guided in brackets 51'and-68 and have threaded engagement with gear nuts generally indicated at 69 and 68. To simultaneously drive the two gear nuts, a pair of pinions 6I and 62 are secured to a common pinion shaft 63 which is driven by a motor 64. By moving the wedgeblocks 53 and 54 inwardly the upper movement of platen I2 is reducedand conversely by moving the wedges outwardly the platen I2 may move to a higher position. Increasing or decreasing vertical movement of platen I2 eiects -a corresponding in-A crease or decrease of the volume of die 2l inasmuch as plunger 24 remains stationary. 'I 'he cooperative relation of the wedge mechanism to the crosshead I4 is such that the wedges may be adjusted during continuous operation of the press without stopping the same thereby permitting adjustment between successive products or any se- 'as a unitary part of, a support 89 which is v'ertically adjustable by the screw 89'. The upper end of the bellows is vsecured to a container 9| .which is biased downwardly by a spring 92. A fulcrum 93 engages a wedge arm 94 pivotedcat 95 while the outer end of the arm carries a pair of resilient wedge actuating lingers 96 and 91.

Operation of dimensional control-Assuming that the' control apparatus is -set for a predetermined dimension of the products 1|, when the control circuit is energized by the pawl and ratchet control 14, 15 and 16 the valve 98 is raised and air pressureis supplied to jet 10. If the product' II has a smaller dimension than desired the clearance between the top of the article and the jet orice will be larger than normal and accordingly air pressure may flow more freely from.

the jet resulting in a corresponding drop of pressure in the jet pipe 18 below normal.

ybetween the force of spring 92 and the air pres-l sure ln bellows 81 and accordingly spring 92 will tainer 9I downwardly causes wedge arms 94 to move downwardly about a pivot'95 thereby to I t i .permit linger 91 to close a micro-switch genproduct from beneath the plungerA 30 on to the discharge table 66 but inasmuch as such devices per se do not constitute part of my present invention it vwill sufElce to diagrammatically indicate such a device by a dotted outline 61. The novel arrangement constituting the improved di- `mensional responsive means includes an air jet resulting from varying dimensions of the product, c to actuate the wedge motor 64 either forwardly or reversely as the case may require. It is also desirable to measure say only every sixth article thereby avoiding too frequent adjustment. To energize-:the control circuit in response to only 19 to wedge operating motor 64 and also to 'at follow-up contact servo-motorA Illl. The wedge motor 64 causes the wedges to be moved outwardly thereby permitting the crosshead I4 and mold platen I2 to moveto a higher position dur ing the next operation.v Such a higher position a selected number of articles I provide a pawl Y 14 pivotally-and yieldably supported on the platen vI I for actuating va ratchet 15 mounted on the press frame near the upper end of the platen stroke. Hence, as the platen moves upwardly' on each stroke it will successively engage the ratchet teeth until nally an electrical contact 16 carried and accordingly stop the first article beneath jet 1 18. Simultaneously a solenoid 82 is energized to open a valve 83 thereby admitting air'pressure from a suitable constant pressure source diagrammatically indicated at 84 through pipes 85 and 86 -to a sylphon bellows 81. Supply pipe 84 is conof the mold platen I2 increases the depth of the -mold 2| above the top of stationary plunger 24 thereby to increase the axial dimension of the tating by having slidable contact with a guide Il'l4.` When the block Il l2 has moved a predetermined distance the micro-switch |00 will move f away from linger 91-and accordingly open the switch and therebydiscontinue operation of the motor IDI and switch operating motor 64. The press will then make, its next stroke and on its up stroke will rotate ratchet 15 sofas to break `engagement of contacts 16 and 11'thereby to deenergize the control circuit. Upon deenergization of the control circuit the valves 83 and 98 close -and solenoid 88 is deenergized to allow stop arm 8| to drop out of the panier the arucIes .thereby permitting the next series of articles td discharge freely from the conveyor 68. 'When the next predetermined number of articles, specically shown herein as six, are formed, then the pawl and ratchet 14 and 15 will again reenergize thecircuit.' Stop arm'8l will be then4 moved in front of the rst article and the air supply will beturned on. If the articleis now of greater height than desired, then the clearance between the jet and article will be reduced below normal thereby restricting the flow of air from pipe 10 and accordingly cause an increase of pressure in the bellows with'consequent raisl ing of finger 13 and closure of micro-switch |86 I by nger. I Closure of thisswitch will reversely operate both the switch motor 64 and the follow-up motor IUI. 'I'he wedgeswill accordingly.'

be moved inwardly to decrease the effective length of the mold cavity while the block |02 will be -moved upwardly until its switch is opened. The sensitivity of the apparatus as well as the normal position of the jet may be varied by an adjusting screw .|09 which raises and lowers jet 10, the contact arm 94 being adjusted by screw 89. The foregoing plus or minus adjustment of the mold cavity will be repeated as often as is' necessary to maintain a uniform dimension and hence it is not necessary to repeat further the successive measuringand adjusting operations.

To stabilize the dimensional control apparatus in between successive measurements of the articles, the switch arm 94 is clamped as shown in Fig. 4 between a stationary back |08 and a spring A pressed piston |09. IIihis clamping action is released When valve, 98 is raised by energization of solenoid 99 thereby supplying iluid pressure from pipe 84 to a pipe I0 for moving piston |09 'outwardly against the spring A small amount of clearance is permitted between the I switch arm 94 and the plate |08 and piston |09 when the clamping pressure is released thereby avoiding friction en the switch arm. Conversely, when valve 98 is closed, then fluid pressure on piston |09 is exhausted through valve 98 and pipe ||0 whereupon spring clamps switch arm 94 between piston |09 and stationary back |08. To further sensitize the equipment arm 94 is provided with a counterweight ||2 having a spring connection extending over a pulley of an indicator pointer H3 thereby to register on a dial ||4 the-extent of displacement of arm 94 from neutral.

In order to obtain dimensional control without duouo'n of powdered metal products. n is also seen that my improved automatic adjusting control effectively regulates the amount of nil and that this control isoperative to measure ilnished pieces produced by the machine. -Such automatic equipment may beused regardless of the character of material used or of the type of press in which the material is compressed, although in the specific 'aspect of my invention disclosed herein a hydraulic press is adapted in combination with the densifying responsive means to control the density of the products in cooperation with dimensional control thereof. The diautomatic adjustment thereof, the circuit 'I9 will be disconnected and two adjustable stop-pins H5 are placed on `side columns 2 and 3 beneath upper platen so as to limit downward move- -lment thereof and thereby definitely establish a fixed dimension for the product. 'I'he pins have heads and Shanksy ||6 slidably received in suit-l able vertical openings found in the side columns. Shims Ill may be inserted to obtain any desired dimension. This dimensional control may be accompanied by density control by manually controlling the adjustment of the wedge stops 53 fand 54 through closing one or the other of reversingor forward switches ||8 and ||9 connected to a suitable source of current. This current actuates motor 64 and thereby adjusts the wedges 53 cavity 2| and accordingly determine the amount of iill'and the density of the product. From this disclosure it is seen that during manual dimensional control through use of stops H5 the adf justing wedges perform a density control function but during automatic dimensional control the wedges perform a dimensional control function, the pins ||5 are removed when the auto matic dimensional control is employed. During automatic dimensional control, density control is 'obtained by controlling the hydraulic pressing fluid pressure. Also" during automatic dimensional control the switches I0 and ||9 permit a preliminary dimensional -adjustment `of vwedges mensional accuracy of the equipment is further enhanced by the cooperative action of the preshrunk ring 22 on the die mold -20 thereby maintaining the radial dimension of the article.

It. will of course be understood that various changes in details oi construction and arrangement of parts may be made by those skilled in the art without departing from the spirit ofthe invention as set forth in the appended claims.

I claim:

1. Apparatus for Vforming products of loose material comprising, in combination, a platen having a mold, means for adjusting the effective depth of said mold to control the axial dimension Y includes an `air jet directed against a product with a predetermined clearance whereby anyv product whose dimension causes a variation in said clearance then said clearance will produce a corresponding change in jet pressure, and means responsive to the change in jet pressure from a predetermined value for adjusting the eil'ective depth of the mold.

4. Apparatus for forming products of loose material comprising, in combination, a press having a platen mold, a compressing plunger,

' and 54 so as to adjust the height of the mold ll and 54 while the air jet control effects a precision control.

From the foregoing disclosure it is seen that YI have providedl improved press equipment that is relatively simple and rugged combined .with positive operationl that has a high degree of sensitivity. accuracy and V responsiveness in'the propower operated means for adjusting the effective depth of the mold to vary the axial dimensmn of a product formed in the mold, means for measuring the axial dimension of a product discharged from the press, and means controlled by said measuring means for initiating operation of said power means.

5. The combination set forth in claim 4 further characterized in that said means which is responsive to the measuring means includes relativelymovable cooperating elements which upon va predetermined movement of one of said elements effects said initiation of the power means, and means also initiated by said predetermined relative movement for causing actuation of the other of saidA elements'until the initial relationship between -the elements is re-established thereby to discontinue any further dimensional adjustment of the mold.

6. The combination set forni in omini 4 mr-v ther'characterized by the provision of means for adjusting the measuring means so ast'o establish a-predetermined dimension for the products.

7,. The combinationset forth in claim -i rurther characterized in that said measuring means and dimensional adjusting means forthe mold are rendered periodically operative automatically in accordance with the number ofA products produced.

8. The combination set forth in claim 4 further characterized in that said measuring means and said dimensional control means for the mold are controlled by an electrical circuit, and means actuated in accordance with a predetermined operation of the apparatus for controlling said circuit and thereby initiating the measuring operation. 'v 9. Apparatus for forming products of loose material comprising, in combination, mechanism for forming the products including a mold and a plunger, means for adjusting said mechanism to vary a dimension of the products, means for measuring said dimension of the products after they are discharged from said forming mechanism, and means responsive to said measuring means for actuating said dimensional adjusting means when the dimension of the product varies from a predetermined value.

A10. Apparatus for forming products yof loose material comprising, in combination, a platen having a mold, means for adjusting the effective depth of said mold to control the axial dimension of a product formed therein, means for prelirninarily actuating said adjusting means to bring the effective depth of said mold within predetermined axial limits, precision adjusting means for also actuating said adjusting means to vary the depth of said mold, means for measuringthe axialdimension of a product discharged from said mold, and means for automatically rendering said precision adjusting means operative in response to said measuring means'when the measurement varies from a predetermined value. Y

k11. The combination set forth in claim 10 fur-- y ther characterized by the provision of means for JOHN B. CUTLER

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