U.S. patent application number 15/450691 was filed with the patent office on 2017-09-21 for method and system for surface densification.
The applicant listed for this patent is GM Global Technology Operations LLC. Invention is credited to John M. Kremer, Wenying Yang.
Application Number | 20170266726 15/450691 |
Document ID | / |
Family ID | 59855203 |
Filed Date | 2017-09-21 |
United States Patent
Application |
20170266726 |
Kind Code |
A1 |
Kremer; John M. ; et
al. |
September 21, 2017 |
METHOD AND SYSTEM FOR SURFACE DENSIFICATION
Abstract
A method for densifying a surface of a powder metal part,
includes blending a plurality of powdered metals to form a powder
metal blend, actuating an upper punch and a lower punch to apply
pressure to the powder metal blend to compact the powder metal
blend, sintering the compacted powder metal blend in an oven,
forming the compacted powdered metal blend into the powder metal
part, heating a portion of the surface of the powder metal part,
and densifying the portion of the surface of the powder metal part
for a predetermined period of time after the portion of the powder
metal part is heated to a predetermined temperature.
Inventors: |
Kremer; John M.; (Sterling
Heights, MI) ; Yang; Wenying; (Rochester Hills,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM Global Technology Operations LLC |
Detroit |
MI |
US |
|
|
Family ID: |
59855203 |
Appl. No.: |
15/450691 |
Filed: |
March 6, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62309658 |
Mar 17, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B22F 2003/1054 20130101;
B22F 2999/00 20130101; B22F 3/03 20130101; B22F 2003/1053 20130101;
B22F 2203/11 20130101; B22F 2998/10 20130101; B22F 2999/00
20130101; B22F 2202/11 20130101; B22F 3/105 20130101; B22F 2003/248
20130101; B22F 3/18 20130101; B22F 2999/00 20130101; B22F 2998/10
20130101; B22F 3/02 20130101; B22F 2003/248 20130101; B22F 3/164
20130101; B22F 2202/07 20130101; B22F 3/02 20130101; B22F 3/10
20130101; B22F 3/164 20130101; B22F 2203/11 20130101; B22F 1/0003
20130101; B22F 5/08 20130101 |
International
Class: |
B22F 3/03 20060101
B22F003/03; B22F 3/105 20060101 B22F003/105 |
Claims
1. A method for densifying a surface of a powder metal part, the
method comprising: blending a plurality of powdered metals to form
a powder metal blend; forming the powdered metal blend into the
powder metal part; actuating an upper punch and a lower punch to
apply pressure to the powder metal blend to compact the powder
metal blend; sintering the compacted powder metal blend in an oven;
heating a portion of the surface of the powder metal part; and
densifying the portion of the surface of the powder metal part for
a predetermined period of time after the portion of the powder
metal part is heated to a predetermined temperature.
2. The method of claim 1 wherein heating the portion of the surface
of the powder metal part includes heating the portion of the
surface of the powder metal part to a temperature between
300.degree. C. and 700.degree. C.
3. The method of claim 2 wherein the predetermined temperature is
maintained using a temperature control feedback system.
4. The method of claim 3 wherein the temperature control feedback
system uses closed loop temperature control with infrared
monitoring or the like for heating the portion of the surface of
the powder metal part to a temperature between 300.degree. C. and
700.degree. C.
5. The method of claim 1 wherein densifying a surface of the powder
metal part includes applying a point load on the portion of the
surface of the powder metal part using a conical shaped tool.
6. The method of claim 1 wherein heating a portion of the surface
of the powder metal part includes heating a linear portion of the
powder metal part.
7. The method of claim 6 wherein densifying the portion of the
surface of the powder metal part includes applying a line load on
the heated linear portion using at least one roller.
8. The method of claim 1 wherein the powder metal part comprises a
gear having gear teeth and densifying the portion of the surface
for the powder metal part includes applying a gear meshing load to
the gear teeth.
9. The method of claim 1 wherein heating the portion of the surface
of the powder metal part includes applying an induction heat with
an induction heating device.
10. The method of claim 1 wherein heating the portion of the
surface of the powder metal part includes applying microwave
radiation with a microwave device.
11. The method of claim 1 wherein heating the portion of the
surface of the powder metal part includes applying a laser to the
portion of the surface of the powder metal part.
12. A method for densifying a surface of a powder metal part, the
method comprising: blending a plurality of powdered metals to form
a powder metal blend; forming the powdered metal blend into the
powder metal part; actuating an upper punch and a lower punch to
apply pressure to the powder metal blend to compact the powder
metal blend; sintering the compacted powder metal blend in an oven;
heating a portion of the surface of the powder metal part; and
densifying the portion of the surface of the powder metal part,
wherein densifying the portion of the surface of the powder metal
part includes applying a point load on the portion of the surface
of the powder metal part using a conical shaped tool for a
predetermined period of time after the portion of the powder metal
part is heated to a predetermined temperature.
13. The method of claim 12 wherein applying a point load on the
portion of the surface of the powder metal part includes moving the
conical shaped tool axially along the powder metal part.
14. The method of claim 13 wherein applying a point load on the
portion of the surface of the powder metal part includes rotating
the conical shaped tool about an axis of rotation.
15. The method of claim 12 wherein applying a point load on the
portion of the surface of the powder metal part includes rotating
the powder metal part about an axis of rotation.
16. The method of claim 12 wherein the heating the portion of the
surface of the powder metal part includes heating the portion of
the surface of the powder metal part to a temperature between
300.degree. C. and 700.degree. C.
17. The method of claim 16 wherein heating the portion of the
surface of the powder metal part includes applying an induction
heat with an induction heating device.
18. The method of claim 16 wherein heating the portion of the
surface of the powder metal part includes applying microwave
radiation with a microwave device.
19. The method of claim 16 wherein heating the portion of the
surface of the powder metal part includes applying a laser to the
portion of the surface of the powder metal part.
20. A system for densifying a surface of a powder metal part
comprising: a workstation, wherein the powder metal part is
disposed in or on the workstation; a heating element adjacent the
powder metal part and configured to heat a portion of the surface
of the powder metal part to between 300.degree. C. and 700.degree.
C.; a tool adjacent the part and configured to apply a point load
to a portion of the surface of the powder metal part after the
portion of the surface of the powder metal part has been heated;
and a controller configured to control the heating element, the
workstation, and the tool, wherein the controller is configured to
control a rate at which the heating element heats the portion of
the surface of the powder metal part, and a rate of movement of the
tool relative to the surface of the powder metal part.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
application No. 62/309,658 filed on Mar. 17, 2016, the entire
contents of which are incorporated herein by reference.
INTRODUCTION
[0002] The invention relates generally to a method and system for
densification of a surface of a workpiece and more particularly to
a method and system for applying heat to a powder metal workpiece
before surface densification of the workpiece.
[0003] Forming metal parts from a powder metal blend is a well
known technology. A system for forming a powder metal part usually
includes a die that is filled with a powder metal blend. Typical
dies include an upper punch and a lower punch. The powder metal
blend is compacted by actuating the upper punch and the lower punch
to apply pressure to the powder metal blend within a die housing.
Finally, the powder metal blend is typically sintered in an oven or
the like to produce a formed powder metal part. The basic steps in
the powder metal forming and surface densification process include
blending the desired metal powders and filling the die; compacting
the powder metal blend into the desired shape, sintering the
compacted part, machining the sintered compacted part into the
desired final shape; densifying the surface; heat treating the
surface, and finishing the final shape by grinding or the like.
[0004] While current methods and systems for forming powder metal
components and for surface densification achieve their intended
purpose, the need for new and improved methods and systems for
forming and surface densification which exhibit higher mechanical
properties are needed. Accordingly, there is a need for an
improved, system and method for surface densification of powder
metal parts that provides deeper densification into the surface,
less damage to existing bonds, and achieves higher levels of
surface density.
SUMMARY
[0005] According to several aspects a method for densifying a
surface of a powder metal part includes blending a plurality of
powdered metals to form a powder metal blend, forming the powdered
metal blend into the powder metal part, actuating an upper punch
and a lower punch to apply pressure to the powder metal blend to
compact the powder metal blend, and sintering the compacted powder
metal blend in an oven. The method further includes heating a
portion of the surface of the powder metal part, and densifying the
portion of the surface of the powder metal part for a predetermined
period of time after the portion of the powder metal part is heated
to a predetermined temperature.
[0006] In another aspect of the present disclosure heating the
portion of the surface of the powder metal part includes heating
the portion of the surface of the powder metal part to a
temperature between 300.degree. C. and 700.degree. C.
[0007] In yet another aspect of the present disclosure the
predetermined temperature is maintained using a temperature control
feedback system.
[0008] In still another aspect of the present disclosure the
temperature control feedback system uses closed loop temperature
control with infrared monitoring or the like for heating the powder
metal part to a temperature between 300.degree. C. and 700.degree.
C.
[0009] In still another aspect of the present disclosure densifying
a surface of the powder metal part includes applying a point load
on the portion of the surface of the powder metal part using a
conical shaped tool.
[0010] In still another aspect of the present disclosure heating a
portion of the surface of the powder metal part includes heating a
linear portion of the power metal part.
[0011] In still another aspect of the present disclosure densifying
the portion of the surface of the powder metal part includes
applying a line load on the heated linear portion using at least
one roller.
[0012] In still another aspect of the present disclosure the powder
metal part includes a gear having gear teeth and densifying the
portion of the surface for the powder metal part includes applying
a gear meshing load to the gear teeth.
[0013] In still another aspect of the present disclosure heating
the portion of the surface of the powder metal part includes
applying an induction heat with an induction heating device.
[0014] In still another aspect of the present disclosure heating
the portion of the surface of the powder metal part includes
applying microwave radiation with a microwave device.
[0015] In still another aspect of the present disclosure heating
the portion of the surface of the powder metal part includes
applying a laser to the portion of the surface of the powder metal
part.
[0016] In still another aspect of the present disclosure a method
for densifying a surface of a powder metal part includes blending a
plurality of powdered metals to form a powder metal blend, forming
the powdered metal blend into the powder metal part, actuating an
upper punch and a lower punch to apply pressure to the powder metal
blend to compact the powder metal blend, and sintering the
compacted powder metal blend in an oven. The method further
includes, heating a portion of the surface of the powder metal
part, and densifying the portion of the surface of the powder metal
part. The densifying the portion of the surface of the powder metal
part includes applying a point load on the portion of the surface
of the powder metal part using a conical shaped tool for a
predetermined period of time after the portion of the powder metal
part is heated to a predetermined temperature.
[0017] In still another aspect of the present disclosure applying a
point load on the portion of the surface of the powder metal part
includes moving the conical shaped tool axially along the powder
metal part.
[0018] In still another aspect of the present disclosure applying a
point load on the portion of the surface of the powder metal part
includes rotating the conical shaped tool about an axis of
rotation.
[0019] In still another aspect of the present disclosure applying a
point load on the portion of the surface of the powder metal part
includes rotating the powder metal part about an axis of
rotation.
[0020] In still another aspect of the present disclosure the
heating the portion of the surface of the powder metal part
includes heating the portion of the surface of the powder metal
part to a temperature between 300.degree. C. and 700.degree. C.
[0021] In still another aspect of the present disclosure heating
the portion of the surface of the powder metal part includes
applying an induction heat with an induction heating device.
[0022] In still another aspect of the present disclosure heating
the portion of the surface of the powder metal part includes
applying microwave radiation with a microwave device.
[0023] In still another aspect of the present disclosure heating
the portion of the surface of the powder metal part includes
applying a laser to the portion of the surface of the powder metal
part.
[0024] In still another aspect of the present disclosure a system
for densifying a surface of a powder metal part includes a
workstation. The powder metal part is disposed in or on the
workstation. A heating element is adjacent the powder metal part
and configured to heat a portion of the surface of the powder metal
part to between 300.degree. C. and 700.degree. C. A tool is
adjacent the part and configured to apply a point load to a portion
of the surface of the powder metal part after the portion of the
surface of the powder metal part has been heated. A controller is
configured to control the heating element, the workstation, and the
tool. The controller is configured to control the rate at which the
heating element heats the portion of the surface of the powder
metal part, and a rate of movement of the tool relative to the
surface of the powder metal part.
[0025] Further features, aspects and advantages of the present
invention will become apparent by reference to the following
description and appended drawings wherein like reference numbers
refer to the same component, element or feature.
DRAWINGS
[0026] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present
disclosure in any way.
[0027] FIG. 1A is a perspective view of a system for densifying a
surface of a powder metal part using a conical shaped tool to point
load the surface of the powder metal part after the portion of the
surface that the point load is applied is heated to a predefined
temperature for a predefined duration of time, according to the
principles of the present disclosure;
[0028] FIG. 1B is a front view of a system for densifying a surface
of a powder metal part using a conical shaped tool to point load
the surface of the powder metal part after the portion of the
surface that the point load is applied is heated to a predefined
temperature for a predefined duration of time, according to the
principles of the present disclosure;
[0029] FIG. 1C is a side view of a system for densifying a surface
of a powder metal part using a conical shaped tool to point load
the surface of the powder metal part after the portion of the
surface that the point load is applied is heated to a predefined
temperature for a predefined duration of time, according to the
principles of the present disclosure;
[0030] FIG. 2A is a perspective view a system for densifying a
surface of a powder metal part using a set of rollers for applying
a line load to the surface of the powder metal part after the
portion of the surface that the line load is applied is heated to a
predefined temperature for a predefined duration of time, according
to the principles of the present disclosure;
[0031] FIG. 2B is an end view a system for densifying a surface of
a powder metal part using a set of rollers for applying a line load
to the surface of the powder metal part after the portion of the
surface that the line load is applied is heated to a predefined
temperature for a predefined duration of time according to the
principles of the present disclosure;
[0032] FIG. 3 is a schematic illustration a system for densifying a
surface of a powder metal gear using a gear for applying a meshing
load to the surface of the powder metal gear after the portion of
the surface that the meshing load is applied is heated to a
predefined temperature for a predefined duration of time, according
to the principles of the present disclosure;
[0033] FIG. 4 is a schematic illustration a system for densifying a
surface of a powder metal part using a coining die for applying a
surface load to the surface of the powder metal part after the
portion of the surface that the load is applied is heated to a
predefined temperature for a predefined duration of time, according
to the principles of the present disclosure;
[0034] FIG. 5 is a flow chart illustrating a method for forging a
powder metal part and for densifying the surface of the forged
powder metal part, according to the principles of the present
disclosure; and
[0035] FIG. 6 is a flow chart illustrating an alternative method
for forging a powder metal part and for densifying the surface of
the forged powder metal part, according to the principles of the
present disclosure.
DETAILED DESCRIPTION
[0036] The following description is merely exemplary in nature and
is not intended to limit the present disclosure, application, or
uses.
[0037] Referring now to FIGS. 1A-1C, a system 100 for densification
of a surface 102 of a sintered powder metal part 104 and a surface
106 of a powder metal part 108 is illustrated, in accordance with
the present invention. The system 100 includes a densification tool
110 and a heating device 112. Densification tool 110 is conical in
shape and has an annular rim 114. In FIG. 1A, the annular rim 114
of tool 110 is pressed against surface 102 of the sintered powder
metal part 104 and contacts the surface 102. The powder metal part
104 is disposed in or on a mount or workstation (not shown). As the
workstation rotates the powder metal part 104 about its axis, the
annular rim 114 of the tool 110 traverses the surface 102 of the
powder metal part 104, applies a point load to densify the surface
102. In one aspect, a point load is a load applied to substantially
a single point of contact between the annular rim 114 of the tool
110 and the surface 102 of the powder metal part 104. In other
words, as the annular rim 114 of the tool 110 applies a point load
to the surface 102, the porosity at the surface 102 is reduced. In
one aspect of the present disclosure, the tool 110 moves axially
relative to the powder metal part 104 and is thereby applied to the
surface 102 over a predetermined portion of an axial extent of the
powder metal part 104.
[0038] In FIGS. 1B and 1C, the annular rim 114 of the tool 110 is
pressed against the surface 106 of the powder metal part 108 and
contacts the surface 106. The powder metal part 108 is disposed in
or on a mount or workstation (not shown). As the workstation
rotates the powder metal part 108 about its axis, the annular rim
114 of the tool 110 traverses the surface 106 of the powder metal
part 108 and the surface 106 is densified. In other words, the
porosity at the surface 106 is reduced as the annular rim 114
traverses the surface 106. In one aspect of the present disclosure,
the tool 110 moves radially relative to the powder metal part 108,
as the powder metal part 108 is rotated and is thereby applied to
the surface 106 over a predetermined portion of an radial extent of
the powder metal part 106.
[0039] In each of FIGS. 1A-1C, the heating device 112 is positioned
in front of the densification tool 110 relative to the direction of
rotation of the powder metal parts 104, 108. As the powder metal
parts 104, 108 are rotated, the heating device 112 heats up the
surfaces 102, 106 before the densification tool 110 reaches the
heated surfaces 102, 106. Heating device 112, in one aspect of the
present disclosure, is an induction coil, microwave, laser,
electron beam or the like. Heating device 112 is configured to heat
the surface of a powder metal part to between 300 to 700 degrees
Celsius. Additionally, in another aspect of the present disclosure,
system 100 includes a feedback temperature controller (not shown)
that is configured to control the surface temperature of the powder
metal part to between 300 to 700 degrees Celsius.
[0040] Referring now to FIGS. 2A-2B, an alternate system 200 for
densifying a surface 202 of a sintered powder metal part 204 is
illustrated in perspective and end views, in accordance with the
present disclosure. System 200 includes a plurality of rollers or
densification tools 206, three in the instant embodiment, and a
plurality of heating devices 208, also three in the instant
embodiment. The plurality of rollers 206 are positioned at equal
distances around the periphery of the powder metal part 204.
However, the present disclosure contemplates that the plurality of
rollers 206 are positioned around the periphery of the powder metal
part 204 at distances that are not equal. Each of the plurality of
rollers 206, contacts and applies a line load to the surface 202
along a line on the surface of the powder metal part 204 thereby
acting to densify the surface 202. In one aspect, the line load is
a pressure applied by the rollers 206 along a length of the rollers
206 in contact with the surface 202 of the powder metal part 204.
The plurality of heating devices 208 are, also, positioned at equal
distances around the periphery of the powder metal part 204.
However, the present disclosure contemplates that the plurality of
heating devices 208 are positioned around the periphery of the
powder metal part 204 at distances that are not equal. As the
powder metal part 204 is rotated, the plurality of heating devices
208 heat up the surface 202 before the plurality of densification
tools 206 reach the heated surface 202.
[0041] Referring now to FIG. 3, an alternate system 300 for
densifying a surface 302 of a sintered powder metal gear 304 is
illustrated in a side view, in accordance with the present
disclosure. System 300 includes a gear densification tool 306 and a
heating device 308. Gear densification tool 306 is in the shape of
a gear having gear teeth 310 that are configured to mesh with gear
teeth 312 of gear 304. Gear densification tool 306 contacts and
applies pressure to the surface 302 at the area 314 of meshing
contact of the densification tool 306 with the powder metal part
304 and acts to densify the surface 302. The heating device 308 is
positioned at distance from area 314 of meshing contact of the
densification tool 306 with the powder metal part 304 on the
periphery of the powder metal part 304. As the powder metal part
304 is rotated, the heating device 308 heats up the surface 302
before the densification tool 306 reaches the heated surface. While
FIG. 3 includes only a single gear densification tool 306 and
heating device 308, it should be understood that additional gear
powder metal gears 304, gear densification tools 306 and heating
devices 308 may be used without departing from the scope or intent
of the present disclosure.
[0042] Referring now to FIG. 4, an alternate system 400 for
densifying a surface 402 of a powder metal part 404 is illustrated
in a side view, in accordance with the present disclosure. System
400 includes a densification tool 406 and a heating furnace 408.
Densification tool 406 includes an upper punch 410 and a lower
punch 412. Densification tool 406 contacts and applies pressure to
the surface 402 of the powder metal part 404 and acts to densify
the surface 402 through a coining operation. The heating furnace
408 elevates the temperature of surface 402 of the powder metal
part 404 to a temperature of 300 to 700 degrees Celsius. Surface
densification is increased by heating the sintered powder metal
part 404 just before surface densification is performed.
[0043] Referring now to FIG. 5, a method 500 for forming a powder
metal part and densifying a surface of the powder metal part is
illustrated in flowchart form. The method starts with step 502, at
step 502 the die is filled with a powder metal blend. At step 504
the powder metal blend is compacted. At step 506, the compacted
powder metal blend is sintered. At step 508 the sintered powder
metal part is machined to a final shape. At step 510 the machined
powder metal part is heated and the surface of the machined powder
metal part is densified. At step 512, the surface of the powder
metal part is heat treated. At step 514, the surface of the heat
treated powder metal part is ground as necessary to produce a final
product.
[0044] Referring now to FIG. 6, a method 600 for forming a powder
metal part and densifying a surface of the powder metal part is
illustrated in flowchart form. The method starts with step 602, at
step 602 the die is filled with a powder metal blend. At step 604
the powder metal blend is compacted. At step 606, the compacted
powder metal blend is sintered. At step 608 the sintered powder
metal part is machined to a final shape. At step 610 the surface of
the machined powder metal part is heated to a predefined
temperature range. At step 612, the heated surface of the machined
powder metal part is subjected to a densification tool that
densifies the heated surface. At step 614, the surface of the
powder metal part is heat treated. At step 616, the surface of the
heat treated powder metal part is ground as necessary to produce a
final product.
[0045] The description of the invention is merely exemplary in
nature and variations that do not depart from the essence of the
invention are intended to be within the scope of the invention.
Such variations are not to be regarded as a departure from the
spirit and scope of the invention.
* * * * *