US3687588A

US3687588A - Lubricated die and punch assembly for compacting powder material

Info

Publication number: US3687588A
Application number: US70379A
Authority: US
Inventors: Joseph E Smith
Original assignee: Wolverine Pentronix Inc
Current assignee: Wolverine Pentronix Inc
Priority date: 1970-09-08
Filing date: 1970-09-08
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29
Also published as: DE2144071A1; FR2107367A5; NL7111944A; BE772255A

Abstract

A die and punch assembly for use on a powder compacting press for making articles compacted from a powder and means for lubricating the die and punch assembly. The assembly comprises a die plate appropriately mounted to the press and includes an aperture in which a die bushing is mounted, the die bushing having a cavity with a punch slidably and snuggly disposed therein. The punch is actuated by a punch support which is, in turn, carried by a pair of posts extending below the die plate to permit reciprocal movement of the punch within the die cavity. A core rod has one end disposed within a longitudinal bore formed in the punch, while the other end of the core rod is fixedly mounted to the posts below the punch support. A cup-shaped tubular housing carried by the posts encloses the punch support, the core rod support, the punch, the core rod, and the posts with the open end of the tubular housing in a fluid sealing abutment with the lower side of the die plate. An actuating arm extending through the core rod support and the bottom of the tubular housing operatively connects the punch support to an external drive means to selectively cause reciprocation of the punch support. A fluid lubricant reservoir having a predetermined fluid level is connected to the interior of the tubular housing for lubricating the walls of the die cavity during the compacting operation.

Description

United States Patent Smith Aug. 29, 1972 [54] LUBRICATED DIE AND PUNCH [57] ABSTRACT PACTING A die and punch assembly for use on a powder compacting press for making articles compacted from a [72] Inventor: Joseph E. Smith, Birmingham, powder and means for lubricating the die and punch Mich. assembly. The assembly comprises a die plate appropriately mounted to the press and includes an aper- [73] Asslgnee' y g g fi g Lmvcoln ture in which a die bushing is mounted, the die bushing having a cavity with a punch slidably and snuggly Filedi p 1970 disposed therein. The punch is actuated by a punch 21 A L N 70 379 support which is, in turn, carried by a pair of posts ex- 1 pp 0 tending below the die plate to permit reciprocal movement of the punch within the die cavity. A core rod 1.8. C]. has one end disposed a bore 425/351, 425/449 formed in the punch, while the other end of the core [51] Int. Cl ..B30b 11/02, B30b 15/02 rod is fixedly mounted to the posts below the punch [58] Field of Search ..18/16 R, 16 F, 16.5, 16.7; Support 25/DIG. 15

A cup-shaped tubular housing carried by the posts en- 5 References Cited closes the punch support, the core rod support, the punch, the core rod, and the posts with the open end UNITED STATES PATENTS of the tubular housing in a fluid sealing abutment with 3,029,752 4 1962 F ank ..25 I6. 15 the Side 0f the the Plate- Ah actuating 3 132 379 5i1964 C rane .[28/165 tending through the cote rod SuPPOtt and the bottom 3 328 840 7/1967 Vinson ..18/16 F of the tubular housing Operatively connects the Punch 314141940 12/1968 Vinson ..18/16.5 x Support to an external drive means to Selectively cause 3,054,142 9/1962 Hinderer et al ..25/DIG. 15 reclpl'ocahoh of the Punch Support- 3,209,4l6 10/1965 Morton ..25/DIG. 15 A fluid lubricant reservoir having a predetermined 3,524,220 8/1970 Davlson ..18/ 16.7 fluid level is connected to the interior of the tubular Primary ExaminerJ. Howard Flint, Jr Att0rneyHauke, Gifford and Patalidis housing for lubricating the walls of the die cavity during the compacting operation.

9 Claims, 3 Drawing Figures INVENTOR JOSEPH E. SMITH fffvrneys FIG-3 PATENTED M1829 I972 LUBRICATED DIE AND PUNCH ASSEMBLY FOR COMPACTING POWDER MATERIAL CROSS-REFERENCE TO RELATED APPLICATIONS 1969, now abandoned and 875,340,filed Nov. 10, 1969.

BACKGROUND OF THE INVENTION 1 Field of the Invention The present invention relates to powder compacting presses and, more particularly, to an improved die and punch assembly for use in such presses, such an assembly having means for lubricating the walls of the die cavity during the compacting operation thereof.

2. Description of the Prior Art The above mentioned applications disclose means for injecting a fluid or a gas into a compacted mass, such as a binder or plasticizer into a compacted powder material or an inert gas into compressed foodstuff or the like, after compaction of the material and means for making compacted articles of a plurality of different powder materials such as multi-layer pharmaceutical tablets or candies.

In the aforementioned patent applications, methods and apparatus are disclosed which provide for the introduction of metered amounts of fluid, solid or other dissimilar material into a powdered base material prior to or during the compacting operation to obtain saturated compacted relatively small articles such as tablets and pellets.

However, none of these disclosed apparatus or methods provide a means for lubricating a die and punch assembly prior to, during, and after the compacting of the powdered article, which tends to reduce wear and act as a parting agent for the compacted material which may tend to adhere to the die cavity wall and/or to the punch surface.

SUMMARY OF THE INVENTION The present invention comprises a die and punch assembly for a powder compacting press having a die plate with die bushing aperture adapted to receive a die bushing which may have one or more die cavities. The die bushing is retained within the die plate aperture by means of a suitable bonding agent. The die cavity has a punch slidably disposed therein; the punch, in turn, being actuated by a punch support slidably mounted between a pair of posts extending downwardly from the die plate. One end of a core rod extends through a longitudinal bore within the punch and has its other end fixedly mounted to a core rod support which, in turn, is fixedly attached to a post at a position below the punch support. The core rod support, the punch support, the core rod and the punch are enclosed in a cup-shaped tubular housing which is carried by the posts such that the upper open end of the housing is in abutment with the lower side of the die plate in a fluid sealing engagement. Means extending through the lower portion of the housing are operatively connected to the punch support to impart a selected reciprocal movement thereto.

An external reservoir in fluid communication with the interior of the housing has a fluid level which is at least equal to the height of the die cavity such that fluid within the housing will seep through the clearance space between the punch and the die cavity wall to provide a thin film of lubricant therebe'tween and between the die cavity wall and the powder disposed therein to be compacted.

It is therefore an object of the present invention to provide a die and punch assembly for use with a powder compacting press which insures a more reliable and repetitive control of dimensional tolerances by providing a fluid lubricant which minimizes wear between moving parts and acts as a parting agent for the powdered material which may tend to adhere to the die cavity walls after the compaction operation.

Other objects, advantages, and applications of the present invention will become apparent to those skilled in the art of powder compacting presses when a description of an example of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING The description herein makes reference to the accompanying drawing wherein like reference numerals refer to like parts throughout the several views, and in which:

FIG. 1 represents a schematic sectional view of a die and punch assembly constructed in accordance with the present invention with the assembly being shown ejecting a compacted powdered article;

FIG. 2 represents a fragmentary sectional view of the die and punch assembly illustrated in FIG. 1 with a hopper disposed over the die cavity and the die cavity filled with a powder substance; and

FIG. 3 represents a schematic sectional view of the die and punch assembly illustrated in FIG. 1 and taken along line 2-2 thereof with an anvil disposed over the die cavity and the assembly shown in a press position.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring t FIGS. 1-3 of the drawing, there is shown one exampleof the present invention in the form of a die and punch assembly 10 having a die plate 12 adapted to be seated in a counterbore 14 of a table 16 which, in turn, forms a portion of powder compacting press (not shown).

The die plate 12 has a flat upper surface 18 and is held to the table 16 by any suitable means, not shown, such as clamps, screws or the like. The die plate 12 is provided with a cylindrically shaped aperture 20 formed about an axis 22 which is disposed normally to the upper surface 18 of the die plate 12. A cylindrically shaped die bushing 24 preferably formed of a hard material, such as a carbide, is retained within the aperture 20 by a suitable adhesive material disposed between the outer periphery of the die bushing 24 and the surface of the aperture 20. As can be seen in FIGS. 1-3, the die bushing 24 is inserted in the aperture 20 such that the upper face 26 of the die bushing 24 is flush with the upper surface 18 of the die plate 12.

The die bushing 24 has a centrally disposed bore 28 extending normally inwardly from the upper face 26 of the die bushing 24 which is provided with a chamfered portion 30 at the lower end thereof. A single die punch 32 is carried by a punch support 34 in a bore 36 which is centrally disposed in the punch support 34 in axial alignment with a die bushing bore 28. The die bushing bore 28 and the die punch 32 may take any desired peripheral configuration such as a circular or square shape.

Although not shown, the die bushing 24 may have more than one die bore 28, as for example the die bushing 24 may be provided with a plurality of mutually parallel bores disposed in a circular arrangement around the axis 22 and having a regular peripheral spacing with each of the parallel bores extending normally downwardly from the upper face 26 of the die bushing 24 and with each of the die bores having a punch 32 associated therewith.

The punch 32 has a longitudinal bore 38 which slidably and snugly receives a core rod 40 which, in turn, is held by a core rod support 42.

The die plate 12 is further provided with a pair of longitudinal bores 44 (FIG. 3) radially spaced from the axis 22 by predetermined equal distances. Associated with each bore 44 there is one of a pair of downwardly extending

posts

46 and 48. The

posts

46 and 48 are of an elongated cylindrical shape and are retained within the bores 44 by any suitable adhesive, or otherwise held in the bores 44 such as by a press fit assembly or by means of set screws (not shown).

As hereinbefore mentioned, the die and punch assembly includes a punch support 34 which is provided with a bore 36 that is axially aligned with the die bushing bore 28. The elongated cylindrical punch 32 extends axially upward from the punch support 34 and registers with the die bushing bore 28 with the outer diameter of the punch accurately fitted in the diameter of the die bushing bore 28 to define a die cavity 50. The punch longitudinal bore 38 closely fits the outer diame ter of the core rod 40 disposed therein such that the punch 32 is slidably guided over the core rod 40 with the punch 32 being free for up and down movement relative to the core rod 40. The punch 32 hasan enlarged intermediate portion 54, the lower surface of which abuts the upper surface of the punch rod support 34 to aid in transmitting an upwardly directed force from an actuating stem 56 to a powdered material 58 within the die cavity 50. The lower end of the punch 32 is preferably retained within the punch support bore 36 by a suitable adhesive.

The punch support 34 has a pair of diametrically opposed longitudinal bores 60 and 62 (FIG. 3), respectively, adapted to slidably engage the

posts

46 and 48. Thus, upon imparting a reciprocating motion to the punch support '34, the punch support 34 will move toward and away from the die bushing 24 in a sliding relationship with respect to the

posts

46 and 48, whereby the hereinbefore mentioned sliding engagement between the cylindrical punch 32 and the die bushing bore 28 is achieved.

The core rod support 42 is in the form of a plate having a centrally disposed aperture 64 in which the core rod 40 is fixedly mounted. The core rod support 42 is also provided with a pair of

longitudinal bores

66 and 68 radially spaced from the axis 22 by the same distance as the die plate bores 44. The core rod support 42 is positioned at a selected distance from the bottom surface of the die bushing 24 by means of a sliding engagement of the

bores

66 and 68 respectively with the posts 46 and 48.A pair of threaded passages 70 radially extend from the outer periphery of the core rod support 42 and terminate at the

bores

66 and 68, the threaded passages each accommodating a set screw 72. The core rod support 42 may be adjusted up and down the

posts

46 and 48 at a selected distance from the lower surface of the die bushing 24 and locked in place by means of the set screws 72. The centrally disposed bore 64 has a diameter closely fitting the core rod 40 adapted to be disposed therein with the elongated core rod 40 having an enlarged lower end 73 which abuts a step 74 within the bore 64 to limit the upward movement of the core rod 40. The enlarged lower end 73 of the core rod 40 is retained in place by the clamping action of a plug 76 threaded into the lower portion of the core rod support bore 64.

A lower punch support 78 is provided below the core rod support 42 and includes a pair of radially spaced

apertures

80 and 82 which respectively slidably engage the

posts

46 and 48 to guide the lower punch support during reciprocal movement thereof and to maintain the lower punch support 78 in axial alignment with the upper punch support 34. The lower punch support 78 is connected to the upper punch support 34 by a pair of threaded fasteners 84 (FIG. 1) which extend axially upward through a bore 86 in the lower punch support 78 and threadedly engage the upper punch support 34. A sleeve member 88 surrounds each fastener 84 with the upper and lower faces of the sleeve member 88 being, respectively, in abutment with the lower surface of the upper punch support 34 and the upper surface of the lower punch support 78. Thus, as the fasteners 84 are threaded into the upper punch support 34, the punch supports 34 and 78 are fixedly secured to one another and reciprocate as a unit when a reciprocal motion is imparted to the lower punch support 78 through the actuating stem 56. Bores 90 longitudinally disposed in the core rod support 42 slidably receive the outer periphery of the sleeve members 88. The fasteners 84 are preferably angularly disposed 90 from the

posts

46 and 48.

The upper and lower punch supports 34 and 78, the punch 32, the core rod 40 and the core rod support 42 are completely enclosed in a fluid tight cup-shaped tubular housing 92. The housing 92 has a bottom wall 94 with a pair of diametrically opposed

longitudinal bores

96 and 98 that are radially disposed from the axis 22 a distance equal to the spacing of the die plate bores 44 from the axis 22. A pair of threaded

fasteners

100 and 102 respectively extend upwardly through the

housing bores

96 and 98 to engage threaded

bores

104 and 106 formed at the lower ends of the

posts

46 and 48 to fixedly mount the housing 92 thereto and enclose the lower portion of the die and punch assembly 10. An annular recess 108 formed at the upper edge of the housing 92 accommodates an O-ring 110 which abuts the lower side of the die plate 12. Thus, as the threaded

fasteners

100 and 102 engage the posts 46 and 4.8, the O-ring 110 disposed between the upper edge of the housing 92 and the die plate 12, is tightly pressed against the bottom of the die plate 12 to ensure a fluidtight seal.

The lower punch support 78 has a centrally disposed bore 112 in which the actuating stem 56 is fixedly mounted by an adhesive or the like. The actuating stem 56 extends externally of the housing 92 through a centrally disposed bore 114 extending through the housing bottom wall 94. The bore 1 14 is axially aligned with the centrally disposed lower punch support bore 112. A groove 116 formed in the wall of the bore 114 accommodates an O-ring 118 which slidably engages the actuating stem 56 to form a fluidtight seal. The extended end 120 of the actuating stem 56 is operatively connected to a suitable drive (not shown) which reciprocates the punch supports 34 and 78 in a timed manner which will be described in greater detail hereinafter.

The bottom wall 94 of the housing 92 further comprises a pipe thread conical aperture 122 (FIG. 1) in which a fitting 124 is threaded. The fitting 124 is connected to a fluid lubricant reservoir 126 by any suitable pipe or line as shown at 128. The reservoir 126 is indicated schematically in FIG. 1 as being normally filled with an appropriate lubricant at a level 130 maintained substantially even with or slightly higher than the surface 26 of the die bushing 24, such that the fluid lubricant from the reservoir 126 flows through the line 128 into the interior of the housing 92, completely submerging the upper and lower punch supports 34 and 78, the core rod support 42, the core rod 40 and the punch 32, and flowing through the clearance space between the punch 32 and the wall of the die bushing bore 28 to wet the full length of the die bushing bore 28 and the peripheral surface of the punch 32.

The support post 46 has a pair of intersecting drilled passageways 132 and 134 (FIG. 3) which place the interior of the housing 92 in communication with the atmosphere for the purposes of bleeding air from the interior of the housing 92 as the same is filled with the fluid lubricant from the reservoir 126. After the air within the housing 92 has been purged, a bleed plug 136 is threaded into the upper portion of the passageway 132 until its lower end engages a seat 138 formed therein so as to prevent the passage of the fluid lubricant therethrough.

For the purpose of illustration, a typical powder compaction cycle includes a powder filling step (FIG. 2), a compacting step (FIG. 3), and an ejection step (FIG. 1). Briefly, the filling step as diagrammatically illustrated in FIG. 2 comprises a powder supply device or hopper 140 that is disposed over the die plate 12 for filling the die cavity 50 defined by the die bushing bore 28 and the upper end of the punch 32 with the powder material 58. The punch 32 is positioned a suitable distance from the upper surface 26 of the die bushing 24 by means of the actuating stem 56 when the die cavity 50 is filled with powdered material 58. The punch 32 is then further displaced slightly downwardly to draw in a sufficient amount of powder material 58 to insure that the die cavity 50 is completely filled with the powder material 58. The hopper 140 may be vibrated to further insure a complete filling of the die cavity 50. After the filling operation, the hopper 140 is removed by suitable means, not shown, and the upper surface 26 of the die bushing 24 is wiped clean of any excess powder, which can be accomplished by the edge of the hopper 140 being moved transversely across the upper surface 26 of the die bushing 24. The upper surface 26 of the die bushing 24 is preferably polished to a super finish so that there is no possibility of any grain of powder remaining on the surface 26 after the wiping step. An anvil 142 (FIG. 3) is then transferred over the filled die cavity 50 and clamped in position by any suitable means, not shown. The punch supports 34 and 78 are actuated by the actuating stem 56 to force the punch 32 upwardly into the die bushing bore 28 so as to compact the powder material 58 contained within the die cavity 50 against the anvil 142 to form a compacted finished article 144. As the punch 32 is moved upwardly the fluid lubricant having seeped from within the interior of the housing 92 into the clearance space between the peripheral surface of the punch 32 and the wall of the die cavity 50 insures a proper lubrication, preventing friction between the surfaces and providing a substantial reduction of normal wear.

The anvil 142 is then removed from over the die cavity 50 and the punch 32 is displaced upwardly so that its end is substantially flush with the upper surface 26 of the die bushing 24 to eject the compacted article 144 from the die cavity 50. The compacted article 144 may then be picked up by any suitable means and deposited in a suitable container, not shown.

Since the fluid lubricant has wetted the wall of the die cavity 50, the fluid lubricant will also act as parting agent for the compacted article 144 and prevents the article 144 from tending to adhere to the wall of the die bushing bore 28 and to the surface of the punch 32 upper end, thus ensuring an easy ejection of the article 144 from the die cavity 50 and preventing breakage of the compacted article 144 when it is ejected from the die cavity 50. An example of a fluid lubricant is trichloroethylene which is suitable for most applications, however a volatile liquid lubricant would be preferable if the compacted article is later sintered so as not to leave ashes or solid foreign particles imbedded in the mass of the article after sintering. For some applications, it may be found desirable to use a gaseous lubricant rather than a liquid lubricant. When a gaseous lubricant is utilized, the reservoir 126 is closed and the gaseous lubricant is contained therein at a pressure slightly higher than atmospheric pressure.

It can thus be seen that the present invention provides a die and punch assembly for compacting an article from a powdered material which includes means for lubricating the walls of the die cavity and the surface of the punch during the operation thereof; which acts to reduce wear between moving components; and which functions as a parting agent aiding in the removal of the compacted article from the die cavity.

Although only one example of the invention has been described, it is to be understood that other modifications may be made thereto, all coming within the spirit of the invention and the scope of the appended claims.

What is claimed is as follows:

1. In an apparatus for making a compacted powdered article comprising a die plate having at least one die cavity, means for dispensing a powdered material into said die cavity and lower and upper compacting members adapted to be aligned with said die cavity and disposed for relative movement toward and away from each other to compact said powdered material within said die cavity the improvement cavity, said lower compacting member being continuously slidably disposed in said die cavity, a fluid tight housing mounted below said die plate and entirely enclosing said lower compacting member, a fluid lubricant filling said housing and means for pressurizing said fluid lubricant in said housing for lubricating the walls of said die cavity by seepage of said fluid lubricant between said lower compacting member and said walls of said die cavity.

2. The apparatus defined in claim 1, further comprising at least one stationary core rod disposed in said lower compacting member for forming a core hole in said compacted article.

3. The apparatus defined in claim 1 wherein said fluid lubricant is a liquid.

4. The apparatus defined in claim 1 wherein said fluid lubricant is a gas.

5. The apparatus defined in claim 1, wherein said pressurizing means comprises a reservoir disposed externally to said housing and conduit means placing said reservoir in communication with the interior of said housing, said reservoir being filled with said fluid lubricant at a level corresponding at least to the level of the upper extremity of said die cavity.

6. The apparatus defined in claim 1 wherein said lower compacting member comprises a punch having an end engaged in one end of said die cavity and reciprocable therewithin and a punch support connected to the other end of said punch for reciprocating said punch within said die cavity and for providing axial alignment between said punch and said die cavity, said housing enclosing said punch and said punch support.

7. The apparatus defined in claim 6, further comprising post means carried by said die plate, said punch support slidably engaging said post means for reciprocal movement relative to said die plate and means mounting said housing to said post means.

, 8. The apparatus defined in claim 7 wherein said housing is of a cup shaped tubular construction, said punch and said punch support are disposed within said tubular housing, the open end of said tubular housing is in abutment with the lower portion of said die plate in a fluid sealing engagement, and operating means extends through the lower end of said housing and is connected to said punch support for reciprocating said punch support relative to said die plate.

9. The apparatus defined in claim 8, further comprising a longitudinal bore extending in said punch from one end to the other end thereof, a core rod slidably and snugly disposed within said punch longitudinal bore and having an end projecting through said other end of said punch and said punch support, a core rod support fixedly mounted to said post means below said punch support and having means for mounting said core rod on said core rod support in axial alignment with the longitudinal bore in said punch.

Patent No, 3.687.588 Dated August 2 1972 Inventor(s) Joseph Smith 4 It is certified that error appears in the abov-identified'patent and that said Letters Patent are hereby corrected as shown below:

IN THE ZI IAIMS Column 6, line "67 .(l'a'st line) following "cavity" l [(first occnrence) insert a comma I following "improver nent" delete "cavity" (seco'nd occurence) and insert of Column 8, line 21, correct "snugly" "to snuggly Signed and sealed this 2nd day of Ju1y;.1974.

(SEAL) Attest:

EDWARD M.FLETCHER,1JR. c". a MARsnAL-L DANN Attesting Officer Commiss oner of Patents F ORM PO-1050 (10-69)

Claims

3. The apparatus defined in claim 1 wherein said fluid lubricant is a liquid.

4. The apparatus defined in claim 1 wherein said fluid lubricant is a gas.

8. The apparatus defined in claim 7 wherein said housing is of a cup shaped tubular construction, said punch and said punch support are disposed within said tubular housing, the open end of said tubular housing is in abutment with the lower portion of said die plate in a fluid sealing engagement, and operating means extends through the lower end of said housing and is connected to said punch support for reciprocating said punch support relative to said die plate.