US2831212A - Pre-pressing die control apparatus - Google Patents

Description

April 22, 1958 B. B. BELDEN 2,831,212

PRE-PRESSING DIE CONTROL APPARATUS Filed July 294, 1954 4 Sheets-Sheet l N vr o R rD.. M m a n l2 2 l2 l w MW au 9 4 m m M m. .w M. 2 W B .n R y n 2 2 l f G 1 M 6\ wn, .1, l 1| e 11|, 14|| |H|| l s.E l 1111 l, n iw 5 i.-- y 5 s i 6 m A. B n ..HHHMHHMHHNI M I 0 m m niv A 6 l v// .f1 M 1| w if- V m 7 .....HHHHIHMU m o 7 2 L1# "I l A -wwwmliwnnhunnuw 0 1 J 9 w 12 l.

April 22, 1958 Filed July 29, `1954 April 22, 1958 B. B. BELDEN 2,831,212

PRE-PRESSING DIE: CONTROL APPARATUS Filed July 29, 1954 4 Sheets-Shet 3 y r n r 206 i F G 7 El -50 i INVENTOR. @1, i5 syRo/v a. BELDE/v 64W *Li H64 BY A T TORNEV B. B. BELDEN 2,831,212

PRE-PRESSING DIE CONTROL APPARATUS 4 sheets-sheet 4 INVENTOR BYRON B. HELDEN 55F/GQQ w @m EN, 7 /U \V April 22, 1958 Filed .my 29, 1954 ATTORNEY n 2,831,212 1C@ Patented Apr. 22, 195s PRE-PRESSING DIE CONERL APPARATUS Byron B. Belden, Media, Pa.

Application July 29, 1954, Serial No. 446,578

3 Claims. (Cl. Iii-16.7)

This invention relates generally to presses for forming compacts of powdered material.

In the manufacture of anged type articles, formed of powdered material which also broadly includes granular counterbore of the die to suit the depth of the flange to be formed. Only by having a uniform density throughout the article is it possible to eliminate weld lines and cracks between the flange and body and to eliminate hour-glass shrinkage in the article during sintering. It has also been difficult heretofore to make thin walled articles of powdered material, either flanged or straight walled, with a high degree of uniform density throughout.

One object of my invention is to provide improved means for forming anged as well as thin walled compacts, or a combination of a thin wall flanged compact, with a high degree of uniform density throughout.

Another object is to provide means for controlling the flange thickness of an article without changing the depth of the flange-forming counterbore of the die and at the same time maintaining a substantially uniform density throughout the entire article regardless of the iiange thickness.

In accomplishing the flange-forming operation I fill the die with powder and then, through the action of what I call a pre-pressing die control, the powder within the lower portion of the die cavity is made to move upwardly, without compacting it, so that a predetermined amount of powder is displaced or crowded into the flange-forming counterbore suicient to produce a desired thickness of the flange upon subsequent compression, the uniform density of the article being obtained by finally simultaneously pressing the flange and body from the top thereof, thereby eliminating weld lines or cracks or hourglass shrinkage in the article during sintering.

In producing thin walled articles I employ the same combination of operating elements as for the flanged articles but, due to the llexibility of the cooperating relationship of the elements of my combination, I am able to convert these elements so that they may operate on thin walled articles merely by relatively adjusting the pressures of certain of the fluid pressure operating elements.

My present invention is particularly useful with, but is not limited to, a press of the type disclosed in the application of Keith W. Hall, tiled January 18, 1954, Serial No. 404,710, which incorporates a disclosure of my present invention. Hence, for an understanding of certain details of construction of a press employed with my invention, reference is made herein to said Hall application.

Other objects and advantages will be more apparent to those skilled in the art from the following description of the accompanying drawings in which:

Fig. 1 is a vertical section of the upper end of said Hall press, showing the floating head, upper and lower punches, die, and die holder, taken generally along line 1-1 of Fig. 2, certain parts either being shown in elevation, or omitted, for the sake of clarity;

Fig. 2 is a similar vertical section of said press, taken generally along line 2 2 of Fig. 1, certain parts being in elevation, or omitted, for the sake of clarity;

Figs. 3 through 7, are diagrammatic sections of tive phases of a cycle of the press head showing how my invention functions in cooperation with the die and punches of the oating head in the formation of a compact; and l Figs. 8, 9 and l0 are similar diagrammatic views to show the formation of a more complicated anged article.

In the particular embodiment of the invention which is disclosed herein merely for the purpose of illustrating one specific form among possible others that the inven- -tion might take in practice, I show in Figs. 1 and 2 the upper portion of the press shown and described in said Hall application and, for the sake of clarity I use, as

nearly as possible, the same numerals herein as therein employed in describing similar parts. In these Figs. 1 and 2, laterally spaced vertical standards 4 and 5 extend upwardly from opposite sides of a housing (not shown) and supported upon the upper ends of these standards are two stationary gear housings, generally indicated at 8, for adjusting the amount of oat of a floating die S8 to be described later. Spaced above housing 3 is a oating head 11 which is secured to the upper ends of four vertically reciprocating tie rods such as 12. The lower ends (not shown) of these tie rods are connected to vertically movable crosspieces at the lower end of the press, which in turn are connected by four connecting rods to crank pins mounted in shafts that carry the main operating gears, so that rotation of these gears causes iioating head 11 to reciprocate vertically. lThe press of the Hall application is further provided with a die platen 50, having four arms 51, in which are secured the lower ends of four support columns 52. The die platen is guided by a pair of rods 96 whose upper ends are slidably guided in a housing 8. The upper ends of support columns 52 are secured on opposite sides of the press to two crossheads 53 which are connected to pistons 54 of die iloat cylinders 55 mounted on each side of the press on top of stationary gear housings 8. Pistons 5d of the die iloat cylinders are normally biased upwardly by iuid pressure admitted through passages 56 from any suitable source of constant pressure while the upper ends of the cylinlders are open to atmosphere. Die platen 5t) is provided with a usual vertical die opening 57 to receivev said floating die 58 whose cavity may be of any desired internal configuration. Upper and lower punches 60 and 61, respectively, and core rods 147 and 213 cooperate with die 58 to compact powdered material therein, as particularly described in said Hall application. During this compaction the die oats downwardly against the constant pressure in float cylinders 55 and in order to adjust the eX- tent of this downward movement all four of the support columns 52 have threads 62 with limit nuts 63 thereon adapted to engage surface 64 of gear housing 8, thereby limiting the downward motion of the die platen.

The construction and operation of floating head 11 which adjustably supports upper punch 60 are substantially identical with the construction and operation of the floating head shown in Fig. 2 of Saaris Patent No. 2,572,- 953, and therefore need not be herein described, except to say that in place of an intensifier, as used by Saari, a. hydro-penumatic accumulator 205 is herein employed to supply constant pressure fluid to the tloating head. The

purpose of such fioating head is to maintain a predeterminedand' uniform applied force," throughthe upper" punch, on the material of an article being compacted within certain variations of the till within the die cavity. Lower punch`V 61; whichejects eacharticle when'comr pacted, is connected tov and actuated b'ysuitab'le mechanism, as` described in' said Hall application, that raises sleeve82 and punchI support 80which` carries with" itL lower punch 61.

To eifect the objects of my invention, I'providea cross member 200 which is secured by studs 201 to floating head 11. Each of two identical cylinders`202, mounted on the outer ends of cross member 200 by' bolts 202, contains a piston 203 whose pistonl rod 203 threadedly supports a sleeve 204 whichmay be axially' adjusted"on-th'e` piston'rod. Pistons203 'are' normally biased downwardly by constant pressure uidwhich maybe'takenfrom any suitable source but preferably from hydro-pneumatic ac# cumulator 205, as`aforesaid. Sleeves 204 are in axial. alignment with and "are'adapted to` engage the upperl'ends 205 of the piston'rods of dieoat cylinder pistons 54.

Operation.-When the press is voperated, iioating head 11 and upper punch 60 attached thereto moveV downwardly. In the ordinary operation of this punch it would enter the die cavtiy' to compact the powdered material therein and thereby produce friction between the material and the die walls to cause the die tofioat downwardly against the constant pressure in the lower end of die oat cylinders 55. However, this floating action may not be sensitive enough for certain types of articles'being` formed or kinds 'of materials being used. Such floating action may produce initial compaction of the article vby the upper punch which results in weld lines or cracks. To overcome this I produce a positive downward force on the die to make it have movement dependently with' the upper punch. To accomplish this I provide sleeves 204 for engaging upper ends 206 of the piston rods of' die float cylinders S5, thereby forcing the die downwardly. In other words, by controlling'the accumulator pressure the pressure in cylinders 202 can be sufficient so that 'a portion of the force generated in the measured strokeY of the upper punch head overcomes the pressure in die float cylinders 55. Such movement of the die causes the powdered material to be more equally distributed to all parts of the die, particularly to those parts forming flanged portions of hanged articles, before complete compaction' of the material so that weld lines and cracks between flanges and body will be eliminated. L'engthening or shortening sleeves 204 by adjusting them axially on threaded piston rods 203' has the effect'of'determining' the thickness of anges of flanged compacts."

In making a straight walled part such as a bushing, itf

is sometimes desirable to have a differential movement between the die, core rod, and the punches in order to reduce the friction between the die wall and the materialV being compacted as well as reducing the friction between the particles of material themselves. This is accomplished in my invention by setting the core rod oat resistance to a predetermined substantially constant value and then using the pre-pressing die control cushions to overcome the resistance of the die oat cushion cylinders which produces the resistance to movement of the die. This causes the die to move faster than the core rod and slower than the top punch. For example, when the upper punch tlinitially engages the material in the die, the pre-pressing lower part of the die cavity between the material and the die'SS.' This'friction is added to the resistance in the die oat cushion cylinders S5 and soon becomes greater than the pressure in the pre-pressing die control cylinders 202. When this happens the top punch starts moving faster than the die holder giving the effect of both top and bottom punches moving into the die simultaneously. Theoreticaly at this point the die is moving at substantially one half the speed of the top punch. The fact lthat'the resistance to movement of the core rod is constant and adjustable, gives a differential movement between the core rod and die wall. This gives the effect of rolling the particles of material against each other, particularly in the case of thin wall bushings and reduces friction of the particles of material against each other, the result being a more uniform density in the part being compacted. Since the pre-pressing sleeves 204 and the top punch are adjustable independently of each other it ispossibleto predetermine the exact relative position of the top. punchv tothe die at the point where thepre-pressing cylinders start to move. By adjustingV the point at which the die starts moving, with relation to the top punch entrance,.

it is possible to control the amount of powder that Vwill be in the ange section ofthe part. do not ow under pressure, experiments have proven that it is possible to displace powder in the die before the actual compacting takes place.

Figs. 3 to 7 inclusive show diagrammatically how my device functions with relation to the die, core rod, punches, feeder shuttle, et cetera. In Fig. 3, while lower punch. 61 is in the up position, a feeder shuttle 165, as shown and` described in said Hall application, covers the die cavity filling it withV powdered material. Sleeves 204 arev inA axial alignment with die holder S0 but withdrawnY from contact therewith or with any members 205 connected therewith. A4 anged compact 100' is shown being ref moved from the wear plate by a pusher end 184. In

Fig. 4, lower punch 61 has descended and the additional.-

each other. Fig. 5 shows that sleeves 204 which possess` the-full force of the measured stroke of the.l1ead,.except as softened by the pressure in cylinders 202, haveforcibly.l

floated die holder 50 downwardly to its stops. Core rod 147l has also floated downwardly to rest on its. stop. Upper punch 60 has reached the extent of its measured'. downstroke, completing compression of` the material. Fig. 6 illustrates the beginning of the ejectionv of thevcompact by lower punch 61. wardly and sleeves 204 are also being vmoved upwardly out of Contact with upper ends 206, allowing iiuid pressure in the lower ends of die oat cylinders S5 to be restored to cause die platen 50 to rise to its initial position. Finally, Fig. 7 shows that lower punch 61, relieved of the compacting pressure, has moved the finished compact upwardly until it is on a levelwith the wear plate from. which position it will be pushed to the left by pusher end 184 as feeder shuttle 16S Vmoves over the die cavity. Upper punch 60 and sleeves 204 have been moved farther upwardly by the rising head and will continue to be moved upwardly until the crank pins on the main gears of the press pass their upper dead centers when upper'punch 60 will start to descend to begin again the cycle of operation.

As shown in Figs. 8, 9, and l0 my pre-pressing die float' control permits bushings of different flange characteristics to be formed, such as a liange 210'positioned between the ends of the bushing body. The various operating elements diagrammaticaly disclosed in these figures: arefgiven the same reference numerals as in the other figures. For

Although metal powders Die 58 and'core rod.` 147 have started to float downwardly. independently of f Upper punch 60 is movingfuppurposes of understanding, piston and cylinder 150 and 151 for controlling floating die 58 and pistons and cylinders 54 and 55 for controlling core rod 147 are diagrarnmatically shown in these views.

From the disclosure herein it is seen that I have provided simple, effective and economical means for adjusting the ange thickness of ilanged articles and of controlling the density of flanges and bodies of flanged articles and of straight-walled parts and of eliminating weld lines or cracks between ilanges and bodies of compacts.

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

I claim:

l. A press comprising, in combination, a Floating die means having a flange-forming counterbore in its upper portion, a lower punch for closing the lower end of the die, die oat piston and cylinder elements for biasing the floating die upwardly but allowing yielding downward movement thereof, a top punch, means for moving the top punch downwardly, prepressing die control piston and cylinder elements interposed between the floating die means and the means for moving the top punch, one of said elements being spaced from one of said means and having provision for operative engagement therewith for moving the die means downwardly by the means for moving the top punch when the top punch has moved a predetermined distance downwardly at which time the top punch initially closes the top of the die cavity, means for yieldingly biasing said piston and cylinder elements in a direction away from each other with a force of such predetermined magnitude that when said operative engagement is efiected and the top punch continues downwardly the floating die is moved downwardly with the top punch, thereby causing relative movement between the lower punch and the die so that material in the die is displaced from the lower portion thereof upwardly into the ange-forming counterbore before compaction of the material takes place, and means for ultimately stopping downward movement of the oating die so that continued downward movement of the top punch causes the prepressing die control elements to yield and thereby allow compaction of material in the die.

2. A press comprising, in combination, a oating die means having a cavity, a lower punch for closing the lower end of the die cavity, die float piston and cylinder elements for biasing the floating die means upwardly but allowing yielding downward movement thereof, a top punch, means for moving the top punch downwardly, prepressing die control piston and cylinder elements interposed between the floating die meansand the means for moving top punch, one of said elements being spaced from one of said means and having `provision for operative engagement therewith for moving the die means downwardly by the means for moving the top punch when the top punch has moved a predetermined distance downwardly at which time the top punch initially closes the top of the die cavity, means for yieldingly biasing said piston and cylinder elements in a direction away from each other with a force of such predetermined magnitude that when said operative engagement is effected and the top punch continues downwardly the iioating die is moved downwardly with the top punch thereby causing relative movement between the lower punch and the die, and means for ultimately stopping downward movement of the floating die so that continued downward movement of the top punch causes the pre-pressing die control elements to yield and thereby effect compaction of material in the die.

3. The combinationin claim 2 further characterized by the provision of means for supporting the die control piston and cylinder elements by the means for moving the top punch downwardly thereby to eect simultaneous downward movement or" the top punch and the die control piston and cylinder elements, and the spaced one of said elements being spaced from the floating die.

References Cited in the ile of this patent UNITED STATES PATENTS

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