WO2002038695A2

WO2002038695A2 - Apparatus and method for lubricating a die cavity

Info

Publication number: WO2002038695A2
Application number: PCT/US2001/050015
Authority: WO
Inventors: Glenn L. Beane; David S. Lashmore
Original assignee: Materials Innovation, Inc.
Priority date: 2000-11-10
Filing date: 2001-11-09
Publication date: 2002-05-16
Also published as: WO2002038695A3; AU2002231241A1

Abstract

An apparatus and method for applying a lubricant to an interior surface of a powder press die cavity (103) is provided. The apparatus includes at least one lubricant reservoir (121) operatively connected to a meter. There is a pump (102) for delivering and removing lubricant from the interior of the die cavity and a sequencing device (130) for sequencing the delivery and removal of the lubricant from the powder press die operatively connected thereto. At least one bore (111) goes through a wall of the press die and extends from the exterior of the die to the die cavity. The lubricant flows through this bore which openly communicates with the pump.

Description

APPARATUS AND METHOD FOR APPLYING LUBRICANT TO THE SURFACE OF A DIE WALL CAVITY

BACKGROUND OF THE INVENTION In the compaction of metal powders by powder metallurgy

(..p/M") _to f_{orm a} metal composite part, metal powders are pressed in a die cavity to form a green compact that is then typically heat treated to form a metal composite part. During compaction, a considerable amount of friction is generated between the metal ^powders and the surfaces defining the die cavity, causing 'both adhesive wear on the die surfaces and breakage of the green compact when it is released from the die cavity. To decrease these frictional effects and also to reduce the ejection force required to remove the green compact from the die, lubricants have been previously added ? to the metal powder mixture. These are generally referred to as internal lubricants since they are dispersed throughout the portion of metal powders to be compacted.

Wet lubricants have not been used successfully since they promote clumping of the metal powder, thereby precluding the good flow characteristics normally desired of P/M materials. Dry lubricants have been used successfully since they are non- binding, and do not affect flow characteristics. Dry lubricants typically function by melting due to the pressure and temperature employed during compaction, thereby allowing the melted lubricant to flow. However, one consequence of the inclusion of any internal lubricant in the metal powder formulation is that the attainable final density and the strength of the metal composite part thus produced are less than theoretically possible when no lubricant is added.

Prior attempts to eliminate the inclusion of internal lubricant in the metal powder composition focused on spraying lubricants in liquid form on the die wall. Previously, these lubricants included both liquid lubricants and dry lubricants that were dispersed in solvents. However, drawbacks in the size and shape of the green compact arise due both to poor metering and distribution of liquid applied to the die wall. Moreover, use of dispersed dry lubricants can pose numerous health, safety and environmental hazards due to the presence of volatile solvents.

SUMMARY OF THE INVENTION

The present invention overcomes the aforementioned drawbacks and disadvantages by providing an apparatus and a

'method for applying a lubricating material onto a die surface.

The present apparatus and method eliminate the need to include an internal lubricant' -in the metal powder composition.

„ BRIEF DESCRIPTION OF THE DRAWINGS

Fig. la is a schematic drawing of a lubrication apparatus with a single pump and an overflow channel.

Fig. lb is a drawing of a die with an annular channel circumscribing a die cavity serving as an overflow channe1.

Fig. 2 is a schematic drawing of a lubrication apparatus with a single pump.

Fig. 3 is a schematic drawing of a lubrication apparatus with two pumps. Fig- 4 is a sectional drawing of a pneumatically driven piston pump.

DETAILED DESCRIPTION OF THE INVENTION

Fig. la shows an embodiment of the present invention wherein there is a single positive displacement pump 102 which meters and pumps lubricant (not shown) into and out of die cavity 103 in die 10 . The use of a positive displacement pump is for illustrative purposed only. The pump can be any suitable pump including but not limited to any piston type, peristaltic type, and or diaphragm type. Associated with the pump 102 in the die cavity lubricating apparatus 101 is a reservoir 121 to contain and store the lubricant (not shown) and lubricant filter 123 is placed in the lubricant feed line

124 between the reservoir 121 and the pump 102. An inlet bore

107 is provided in the die 104 from an exterior die wall 128 through to a die cavity surface 127 at a position just above the upper surface 108 of the lower punch 105, allowing die cavity 103 to communicate with pump chamber 125 of positive displacement pump 102 via lubricant feed line 111. An annular channel 109 circumscribing die cavity 103 in the upper surface 133 of the die 104 communicates with reservoir 121 via drainage bore 110 and drain line 112. Central logic processing unit (CPU) 130 is connected to valve operator 114 of lubricant valve 113, valve operator 116 of lubricant valve 115, valve operator 118 of pneumatic valve 117, and valve operator 120 of pneumatic valve 119. Lubricant valve 113 is installed in lubricant feed line between the positive displacement pump 102 and the die 104, and lubricant valve 115 is installed between positive displacement pump 102 and lubricant reservoir, ^"121. Pneumatic valve 117 is installed in pressure line 131 between pneumatic cylinder 126 and pressure source (not shown) , and pneumatic valve 119 is installed in pressure line 132 between pneumatic cylinder 126 and pressure source (not shown). In reservoir 121, a mixer 122 maintains the lubricant in a homogeneous state. _? Fig. lb shows the relationship between the annular channel 109 circumscribing the die cavity 103 in die 104, and the drainage bore 110, of the embodiment shown in Fig. la.

Again referring to Fig. la, CPU 130 provides the sequencing of valve operators 114, 116, 118, and 120, for the operation of lubricant valves 113 and 115, and pneumatic valves 117 and 119. Upon command of CPU 130, valve operator 120 opens pneumatic valve 119 in a manner to allow pressure from the pressure source (not shown) to operate pneumatic cylinder 126 in such a way so as to cause piston 124 to raise. Simultaneously, CPU 130 operates valve operator 116 so that lubricant valve 115 opens so that a quantity of lubricant (not shown) , with a volume greater than that of the die cavity 103 when the upper surface 108 of the lower punch 105 is at its lowest point in its stroke, is drawn through filter 123 from reservoir 121 into pump chamber 125 by the raising of piston 124. When positive displacement pump 102 has drawn the prescribed quantity of lubricant (not shown) CPU 130 operates valve operator 116 to close lubricant valve 115, and operates valve operator 120 to close pneumatic valve 119 from the pressure source. Subsequently, on order from CPU 130, valve operator 114 opens lubricant valve 113, thus establishing communication between the lubricant filled pump chamber 125 and die cavity 103. Simultaneously, on order from CPU 130, valve operator 118 opens pneumatic valve 117, thus allowing pressure from pressure source (not shown) to drive piston 124 down, causing lubricant to flow from the pump chamber 125 into die cavity 103 thus flooding it. Excess lubricant (not shown) pumped into the die cavity 103 overflows into the annular channel 109 and flows into reservoir 121. Upper punch 106 is held up and out of die cavity 103 to allow air to escape the ^■die cavity 103 as it fills. The die cavity 103 is subsequently drained when CPU 130 operates valve operator 117 to close pneumatic Naive 118 to the pressure source (not l' ' ' - X^f shown) and operates valve operator 120 to open pneumatic valve 119 to the pressure source (not shown) thus raising piston 124 and drawing lubricant (not shown) from the die cavity 103 into pump chamber 125. Finally, CPU 130 commands valve operator

114 to close lubricant valve 113 in order to isolate die cavity 103 from positive displacement pump 102. Then, upon command of CPU 130 valve operator 116 operates lubricant valve

115 so that pump chamber 125 communicates with reservoir 121. Simultaneously, CPU 130 commands valve operator 120 to close pneumatic valve 119 to pressure source (not shown) and commands valve operator 118 to open pneumatic valve 117 to pressure source (not shown) , thus driving piston 124 down and causing lubricant to flow through filter 123 and into reservoir 121.

Fig. 2 shows an embodiment of the present invention wherein there is a single positive displacement pump 202 which meters and pumps lubricant (not shown) into and out of die cavity 203 in die 204. Associated with the pump 202 in the die cavity lubricating apparatus 201 is a reservoir 221 to contain and store the lubricant (not shown) and lubricant filter 223 is placed in the lubricant feed line 224 between the reservoir 221 and the pump 202. An inlet bore 207 is provided in the die 204 from an exterior die wall 228 through to a die cavity surface 227 at a position just above the upper surface 208 of the lower punch 205, allowing die cavity 203 to communicate with pump chamber 225 of positive displacement pump 202 via lubricant feed line 211. Central logic processing unit (CPU) 230 is connected to valve operator 214 of lubricant valve 213, valve operator 216 of lubricant valve 215, valve operator 218 of pneumatic valve 217, and valve operator 220 of pneumatic valve 219. Lubricant valve 213 is installed in lubricant feed line between the positive displacement pump 202 and the die 204, and lubricant valve 215 is installed between positive displacement pump 202 and lubricant reservoir 221. Pneumatic valve 217 is installed in pressure line 231 between pneumatic cylinder 226 and pressure source (not shown) , and pneumatic valve 219 is installed between pneumatic pylinder 226 and pressure source (not shown) . Again referring to Fig. 2, CPU 230 provides the sequencing of valve operators 214, 216, 218, and 220, for the operation of lubricant valves 213 and 215, and pneumatic valves 217 and 219. Upon command of CPU 230, valve operator 220 opens pneumatic valve 219 in a manner to allow pressure from the pressure source (not shown) to operate pneumatic cylinder 226 in such a way so as to cause piston 224 to raise. Simultaneously, CPU 230 operates valve operator 216 so that lubricant valve 215 opens so that a quantity of lubricant (not shown) , with a volume equal to that of the die cavity 203 when the upper surface 208 of the lower punch 205 is at its lowest point in its stroke, is drawn through filter 223 from reservoir 221 into pump chamber 225 by the raising of piston 224. When positive displacement pump 202 has drawn the prescribed quantity of lubricant (not shown) CPU 230 operates valve operator 216 to close lubricant valve 215, and operates valve operator 220 to close pneumatic valve 219 from the pressure source. Subsequently, on order from CPU 230, valve operator 214 opens lubricant valve 213, thus establishing communication between the lubricant filled pump chamber 225 and die cavity 203. Simultaneously, on order from CPU 230, valve operator 218 opens pneumatic valve 217, thus allowing pressure from pressure source (not shown) to drive piston 224 down, causing lubricant to flow from the pump chamber 225 into die cavity 203 thus flooding it. Upper punch 206 is held up and out of die cavity 203 to allow air to escape the die cavity 203 as it fills. The die cavity 203 is subsequently drained when CPU 230 operates valve operator 217 to close pneumatic valve 218 to the pressure source (not shown) and operates valve operator 220 to open pneumatic valve 219 to the pressure source (not shown) thus raising piston 224 and drawing lubricant (not shown) from the die cavity 203 into pump chamber 225. Finally, CPU 230 commands valve operator

214 to close lubricant valve 213 in order to isolate die cavity 203 from positive displacement pump 202. Then, upon command of CPU 230 valve operator 216 operates lubricant valve

215 so that pump chamber 225 communicates with reservoir 221. Simultaneously, CPU 230 commands valve operator 220 to close pneumatic valve 219 to pressure source (not shown) and commands valve operator 218 to open pneumatic valve 217 to pressure source (not shown) , thus driving piston 224 down and causing lubricant to flow through filter 223 and into reservoir 221.

Referring to Fig. 3, an embodiment of the present ^ invention of a die cayity lubricating apparatus 301 that comprises two separate positive displacement pumps, a flooding pump 302 and a drainage pump 306, to accomplish the flooding and draining of the die cavity 303 with lubricant (not shown) . Flooding pump 302 meters and pumps lubricant (not shown) into die cavity 303 in die 304. Inlet bore 307 is provided in the die 304 from an exterior die wall 342 through to a die cavity surface 309 at a position just above the upper surface 308 of the lower punch 305, allowing die cavity 303 to communicate with pump chamber 330 of flooding pump 302 via lubricant feed line 334. Lubricant flood valve 313 is provided between flooding pump outlet 349 and inlet bore 307. Valve operator 314 is associated with lubricant flood valve 313. Drainage pump 306 evacuates lubricant (not shown) after the die cavity 303 has been flooded. Outlet bore 310 is provided in die 304 from an exterior die wall 343 through to a die cavity surface 312 at a position just above the upper surface 308 of lower punch 305, allowing die cavity 303 to communicate with pump chamber 332 of drainage pump 306 via lubricant drainage line 336. Lubricant drainage valve 327 is provided between outlet bore 310 and drainage pump inlet 344. Valve operator 328 is associated with lubricant drainage valve 327. Die cavity lubricating apparatus 301 includes reservoir 340 to contain and store the lubricant (not shown) . Drainage pump outlet 345 communicates with reservoir inlet 346 in reservoir 340 via lubricant return line 337. Lubricant return valve 325, along with associated valve operator 326, is provided in lubricant return line 337 between drainage pump 306 and reservoir inlet 346 of reservoir 340. Lubricant filter 338 is placed in the lubricant return line 337 between the reservoir 121 and drainage pump 306. Reservoir outlet 347 communicates with flooding pump inlet 348 via lubricant feed line 335, and has lubricant feed valve 315 and associated valve operator 316 installed between the reservoir outlet 347 and flooding pump inlet 348.

Again referring to Fig. 3, CPU 350 provides the sequencing for valve operators 314, 316, 318, 320, 322, 324, 326, and 328, for the operation of their associated valves, respectively, lubricant flood valve 314, lubricant inlet valve 315, pneumatic valves 317, 319, 321, 323, lubricant return valve 325, and lubricant drain valve 327. Upon command of CPU 350, valve operator 320 opens pneumatic valve 319 in such a manner as to allow pressure from the pressure source (not shown) to operate the pneumatic flooding pump actuator 355 in such a way so as to cause piston 331 to raise.

Simultaneously, CPU 350 operates valve operator 316 so that lubricant valve 315 opens so that a quantity of lubricant (not shown) , with a volume substantially equal to that of the die cavity 303 when the upper surface 308 of the lower punch 305 is at its lowest point in its stroke, is drawn from reservoir 340 into pump chamber 330 by the raising of piston 331. When flooding pump 302 has drawn the prescribed quantity of lubricant (not shown) CPU 350 operates valve operator 316 to close lubricarit valve 315, and operates valve operator 320 to close pneumatic valve 319 from the pressure source.

Subsequently, on order from CPU 350, valve operator 314 opens lubricant valve 313, thus establishing communication between the lubricant filled pump chamber 330 and die cavity 303. Simultaneously, on order from CPU 350, valve operator 318 opens pneumatic valve 317, thus allowing pressure from pressure source (not shown) to pressurize flooding pump actuator 355 and thus drive piston 331 down, causing lubricant to flow from the pump chamber 330 into die cavity 303, thus flooding it. Upper punch 329 is held up and out of die cavity 303 to allow air to escape from the die cavity 303 as it fills. Upon completion of flooding the die cavity 303 with lubricant (not shown) lubricant flood valve 313 is closed, and lubricant drain valve 327 is opened, allowing die cavity 303 to communicate with drain pump chamber 332. Valve operator 324 operates to open pneumatic valve 323 to allow pressure from pressure source (not shown) to pressurize drain pump actuator to raise piston 333 in the drain pump, thus drawing lubricant (not shown) from the die cavity 303 into drain pump chamber 332. When ^'the^' die cavity is substantially completely drained of lubricant, lubricant drain valve 327 is closed thus isolating drain pump chamber 332 from die cavity 303, pneumatic valve 323 is closed off from the pressure source (not shown) , and lubricant return valve 325 is subsequently opened thus allowing the drain pump outlet 345 to communicate with reservoir inlet 346. Simultaneously, pneumatic valve 321 is opened to the pressure source (not shown) so that the pump actuator drives the piston 333 down, forcing the lubricant through filter 338 and into reservoir 340. Fig. 4 shows a pneumatic positive displacement pump 401. The pump is comprised of two sections, the pneumatic actuator 403 and the pump section 402. Actuator piston 404 is provided in the pneumatic actuator 403, and is connected to pump piston by piston rod 407, so that any movement of actuator piston 404 is exactly equaled by the movement of the pump piston 405. Threaded rod 406 engages threads 420 in pneumatic actuator cylinder head 421 and is held in place by nut 424. The displacement of pump chamber 425 is variably limited by extending or retracting threaded rod 406 and allowing actuator piston to contact the internal end 408 of threaded rod 406 on its upstroke. Actuator chamber 426 is isolated from upper chamber 427 by intermediate cylinder head 422 and seal 429. Lubricant valve 410 is installed in communication with port 430 and lubricant valve 411 is installed in communication with port 431. Pneumatic valve 412 is installed in communication with pneumatic port 432, and pneumatic valve 413 is installed in communication with pneumatic port 433. In operation, lubricant (not shown) is drawn into chamber 425 when pressure is admitted into actuator chamber 426, raising actuator piston 404 toward pneumatic cylinder head 421, which raises pump piston 405 toward the intermediate cylinder head. Pressure admitted into actuator chamber 428 forces the actuator piston 404 toward the intermediate cylinder head, thus moving pump piston 405 toward the pump head 423, forcing the lubricant through at least one of the lubricant ports 430 and 431. The sequence of opening and closing the valves is controlled by the central logic processing unit (not shown) , and thus the measurement and transport of the lubricant (not shown) can be accomplished.

Although the present invention has been illustrated with reference to certain preferred embodiments, it will be appreciated that the present invention is not limited to the specifics set forth therein. Those skilled in the art readily will appreciate numerous variations and modifications within the spirit and scope of the present invention, and all such variations and modifications are intended to be covered by the present invention, which is defined by the following claims.

Claims

What is claimed is:

1. An apparatus for applying a fluid to an interior surface of a powder press die having a die cavity therein, said apparatus comprising: at least one means for storing and containing said fluid operatively connected to at least one means for metering said fluid; at least one means for causing said fluid to flow into and out of said die cavity having at least one means for sequencing said flow of fluid into and out of the powder press die operatively connected thereto; at least one bore through a wall of the press die extending from an exterior of said die to said die cavity therein, through which said lubricant is caused to flow, said bore openly communicating with said at least one means of causing said lubricant to flow.

2. The apparatus according to claim 1, wherein said bore is located in a vertical wall of said die cavity at a vertical position that is above the lowest vertical position of the upper-most surface of an associated lower press punch

3. An apparatus according to claim 2, wherein said means for metering said fluid and said means for causing said fluid to flow is a positive displacement pump.

4 . An apparatus according to claim 3, wherein said positive displacement pump is a piston pump.

5. An apparatus according to claim 2 wherein said means for sequencing said flow of fluid into and out of the powder press die cavity is a central logic processing unit.

6. An apparatus according to claim 3 _ further comprising a positive displacement pump for removing fluid from said die cavity.

7. An apparatus according to claim 6 wherein said positive displacement pump is a piston pump.

8. An apparatus according to claim 2, wherein said bore is located in a vertical wall of said die cavity at a vertical position that is above the lowest vertical position of the upper-most surface of an associated lower press punch

9. An apparatus for lubricating the surfaces of a die cavity for lubricating the surfaces of a die cavity according to claim 8 wherein a means to collect said excess lubricant is provided.

10. An apparatus for lubricating the surfaces of a die cavity according to claim 8, wherein said means to collect said excess lubricant comprises an annular channel provided in the upper surface of the die, said annular channel circumscribing said die cavity and communicating with an overflow drain in order to return said excess of lubricant to said means of storing and containing said lubricant.

11. A method for lubricating interior surfaces of a die cavity, said method comprising the steps of: providing a die cavity lubricant; flooding said die cavity by causing a volume of said lubricant to flow through at least one bore through a wall of said die cavity, said bore located in an approximately vertical wall of said die cavity at a vertical position that is above the lowest vertical position of an upper-most surface of an associated lower punch; said volume of said lubricant being at least equal to the volume of said die cavity when said lower associated punch is at its lowest vertical position within said die cavity; and subsequently draining said die cavity of said lubricant.

12. A method according to claim 10, wherein said step of metering the volume of said lubricant is carried out before the step of flooding said die cavity.

13. A method according to claim 10, further comprising sequencing the steps of metering, causing the lubricant to flow, flooding, and draining of said die cavity.

14. A method according to claim 10 wherein each of the steps of metering, flooding and draining is respectively carried out by a central logic processing unit.

15. A method according to claim 13, wherein each of the steps is further carried out by at least one positive displacement pump.

16. A method according to claim 13, wherein each of the steps is further carried out by at least one means for storing and containing the lubricant.

17. A method according to claim 10, wherein said flooding is carried out by flowing a volume of said lubricant that is greater than the volume of the die cavity, thereby creating an excess of said lubricant that overflows from said die cavity into an annular channel provided in the upper surface of the die, said annular channel circumscribing said die cavity and then into an overflow drain communicating therewith in order to return said excess^~~of lubricant to said means of storing and containing said lubricant .

18. An apparatus for applying a lubricant to an interior surface of a powder press die having a die cavity therein, said apparatus comprising: at least one lubricant reservoir operatively connected to a meter; a pump for delivering and removing lubricant from the interior of said die cavity and a sequencing device for sequencing the delivery and removal of the lubricant from the powder press die operatively connected thereto,- at least one bore through a wall of the press die extending from an exterior of said die to said die cavity therein, through which said lubricant flows, said bore openly communicating with said pump.

19. The apparatus according to claim 18, wherein said bore is located in a vertical wall of said die cavity at a vertical position that is above the lowest vertical position of the upper-most surface of an associated lower press punch.

20. An apparatus according to claim 18, wherein said pump is a positive displacement pump.

21. An apparatus according to claim 20, wherein said positive displacement pump is a piston pump.

22. An apparatus according to claim 18, wherein said sequencer is a central logic processing unit.

23. An apparatus according to claim 18, further

,( comprising a positive displacement pump for removing fluid .''from said die cavity.

24. An apparatus according to claim 18 , wherein said bore is located in a vertical wall of said die cavity at a vertical position that is above the lowest vertical position of the upper-most surface of an associated lower press punch

25. An apparatus for lubricating the surfaces of a die cavity according to claim 18, further comprising an excess lubricant collector associated with the die cavity.

26. An apparatus for lubricating the surfaces of a die cavity according to claim 25, wherein said excess lubricant collector comprises an annular channel provided in the upper surface of the die, said annular channel circumscribing* said die cavity and communicating with an overflow drain in order to return said excess of lubricant to said reservoir.