U.S. patent number 3,894,676 [Application Number 05/406,678] was granted by the patent office on 1975-07-15 for method for construction of railway bolster.
This patent grant is currently assigned to Chemetron Corporation. Invention is credited to James McKenna, Carl Emil Oppenheim.
United States Patent |
3,894,676 |
Oppenheim , et al. |
July 15, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Method for construction of railway bolster
Abstract
A method for construction of a railway bolster is provided
wherein the bolster bowl and king bolt openings have liners of low
alloy or carbon steel backed by a weld metal deposit with a
hardness of from about 25 to 40 Rockwell C.
Inventors: |
Oppenheim; Carl Emil (West
Dundee, IL), McKenna; James (Atlanta, GA) |
Assignee: |
Chemetron Corporation (Chicago,
IL)
|
Family
ID: |
23609011 |
Appl.
No.: |
05/406,678 |
Filed: |
October 15, 1973 |
Current U.S.
Class: |
228/182;
228/234.1; 228/262.41; 105/226; 228/168; 228/225; 105/199.4;
219/137R; 228/219; 384/423 |
Current CPC
Class: |
B61F
5/04 (20130101); B61F 5/52 (20130101); B23K
9/0026 (20130101); B23K 35/308 (20130101) |
Current International
Class: |
B23K
9/00 (20060101); B61F 5/52 (20060101); B61F
5/04 (20060101); B61F 5/00 (20060101); B61F
5/02 (20060101); B23K 35/30 (20060101); B23k
031/02 () |
Field of
Search: |
;29/471.1,471.5,470.7,472.1,484,490,499,503,530,527.1,527.5
;105/226 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Smith; Al Lawrence
Assistant Examiner: Joyce; Margaret M.
Attorney, Agent or Firm: Esser; N. M.
Claims
We claim:
1. The method of constructing a railway car bolster having an
upwardly facing bolster bowl comprising the steps of forming a bowl
with a flange having a top with a diameter larger than the diameter
of the flange bottom, securing a liner having a generally
cylindrical wall within said bowl and depositing filler weld metal
to fill the space between the liner and the flange.
2. Method according to claim 1 including the steps of making at
least one pass of the weld metal with a rod having a diameter of
about 0.045 to about 0.065 inch.
3. Method according to claim 1 including the step of making
succeeding passes with rods having a diameter larger than about
one-sixteenth inch.
4. Method according to claim 1 including the step of forming the
liner from about 10-gage steel material having a chemical
composition between that specified by the American Iron and Steel
Institute for steel No. 1020 and steel No. 1050.
5. Method according to claim 1 wherein the body of weld metal has
the following composition:
6. The method of claim 1 wherein the body of weld metal has a
hardness of from about 25 to about 40 Rockwell C.
7. The method of claim 1 wherein the depositing of the weld metal
includes the step of shielding the welding operation with a gas
having a major percentage of argon.
8. Method according to claim 7 wherein the shielding gas comprises
oxygen in the amount of from about 2% to about 5%.
9. Method according to claim 7 wherein the shielding gas comprises
carbon dioxide in the amount of from about 10% to about 25%.
10. The method of constructing a bolster according to claim 1
including the step of heat treating the bolster, liner and weld
metal body at a temperature of 1150.degree. for about one hour.
11. A method according to claim 9 including the step of
substantially aligning the top and bottom edges of the cylindrical
liner with the top and bottom edges, respectively, of the
flange.
12. A method according to claim 1 including the step of depositing
weld metal in an amount sufficient to provide a body of weld metal
having a mass greater than the mass of the liner.
13. The method of claim 1 including the step of depositing the
filler weld metal from a fluxless tubular alloy electrode having a
sheath of mild steel and a filler of approximately the following
composition: ferromolybdenum, about 4.5%; ferrochromium, about 17%;
ferrosilicon, about 6%; ferromanganese, about 13%; iron powder,
about 59.5%; and wherein said filler comprises approximately 18% by
weight of the finished electrode.
Description
BACKGROUND OF THE INVENTION
The increased size of railway cars and the higher speeds at which
they have been operated aggravates the wear on the bearing portion
of the truck bolsters which have a hardness of about 8 to about 10
Rockwell C. Structures including a hardened liner for the bolster
bowl have been proposed, but fitting the liner to the bolster and
securing it in place has been a problem. Finishing the interior of
the bolster bowl with a deposit of hard weld metal provides a
satisfactory bond to the bolster body, but the deposited metal must
be ground to provide a bearing surface; this process requires 12 to
16 hours per bolster. Moreover, the weld metal is conventionally
deposited in the down hand position, a practice which requires
frequent repositioning of the bolster in a vertical plane. Attempts
to develop a smoother surface by depositing the weld metal against
a removable form, e.g., of carbon, were unsuccessful.
There remains, therefore, a need for a method of manufacturing and
reconstructing bolsters which is more easily practiced, is
economically attractive and provides a bolster with a satisfactory
or superior working life.
THE INVENTION
It is an object of the invention to provide a railway car bolster
having a bolster bowl and a kingpin opening which furnish excellent
wearing qualities and which can be inexpensively fabricated. It is
a further object of the invention to provide a method of surfacing
bolster bowls and/or kingpin openings which is applicable to newly
constructed bolsters or in restoring worn bolsters to a useful
life. A still further object is the provision of a method which
enables a bolster to be processed in the horizontal position.
These and other objects of the invention are achieved through the
provision of a railway car bolster including an upwardly opening
bolster bowl comprising an upstanding flange, a liner having top
and bottom edges within said flange and defining a generally
cylindrical sidewall within said bowl, and a body of alloy weld
metal encircling said liner. The body of weld metal extends
substantially continuously between said top and bottom edges of the
liner and secures the liner to the flange. The body of weld metal
is preferably larger adjacent the top edge than at the bottom edge
and both top and bottom are thicker than the liner.
In one embodiment the liner is formed from carbon steel having a
thickness of about 10-gage and having a chemical composition
falling between that specified by the American Iron and Steel
Institute for steel No. 1020 and steel No. 1050 or from a low alloy
steel having a composition between that specified by A.I.S.I. for
steel No. 4130 and steel No. 4340.
The body of weld metal has the following composition.
______________________________________ Carbon from about 0.08 to
about 0.15% by weight Manganese from about 1.0 to about 1.75 by
weight Chromium from about 2.0 to about 2.5 by weight Molybdenum
from about 0.4 to about 0.65 by weight Silicon about 0.60 Maximum
by weight Iron Balance ______________________________________
The body of weld metal desirably has a hardness of from about 25 to
about 40 Rockwell C. The large amount of wear resistant weld metal
extending from the top of the built up joint down to the root
serves to give much longer life to this very important part of the
total bolster. It especially counteracts the upsetting or flow of
metal common to the impacting of any force to an edge of this kind.
Thus, there is formed a bolster bowl having three concentric rings
welded into a single body comprising a relatively thin central
liner of low alloy or carbon steel, an encircling and thicker ring
of hard weld metal and, outermost, the bolster bowl flange. The
mass of the deposited body of weld metal is greater than the mass
of the liner ring.
The invention also includes the method of constructing a railway
car bolster having an upwardly facing bolster bowl comprising the
steps of forming the bowl with a flange having a top with an inside
diameter larger than the inside diameter of the flange bottom,
securing a liner having a generally cylindrical wall within said
bowl and depositing weld metal, preferably with an electric arc, to
fill the space between the liner and the flange. Usually the top
and bottom edges of the cylindrical liner are substantially aligned
with the top and bottom edges, respectively, of the flange.
In one embodiment the method includes the step of making at least
one pass of the weld metal with an electrode having a small
diameter, about 0.045 to about 0.065 inch; desirably, succeeding
passes are made with electrodes having a diameter larger than about
0.065 inch.
The step of depositing of the weld metal includes shielding the
welding operation with a gas having a major percentage of argon.
Desirably, the shielding gas comprises oxygen in the amount of from
about 2% to about 5%. Alternatively, the shielding gas may comprise
carbon dioxide in the amount of from about 10% to about 25%. After
welding, the bolster, liner, and weld metal body may be heat
treated at a temperature of 1150.degree. for about 1 hour.
The invention will be better understood from references to the
following drawings which illustrate an embodiment of the invention
and wherein:
FIG. 1 is a top view of a bolster;
FIG. 2 is a sectional view of the bolster of FIG. 1 taken on the
section lines 2--2 in that figure and shows the bolster prepared
for metal deposit; and,
FIG. 3 shows the completed bolster in a sectional view taken on
section lines 2--2 of FIG. 1.
In FIG. 1 there is illustrated a truck bolster 10 which is a
unitary casting and includes a large center section 12 and tapered
arms 14 extending therefrom. Cast integrally with the enlarged
center section 12 on its upper surface is an upstanding flange 16
which forms the periphery of an upwardly extending bolster bowl of
shallow depth. A central bore 20 is provided to accept the kingpin,
not shown, extending from the car underframe.
FIG. 2 presents an enlarged sectional view taken through the
midpoint of the bolster of FIG. 1 and illustrates the bolster bowl
having an upstanding flange 16 and the bowl bottom 17. The inside
of the flange is chamfered at 18 over substantially its entire
height by flame cutting or machining to provide a resevoir for weld
metal. The chamfering is controlled to provide a narrow top edge 19
which is about one-eighth inch wide. Where the section of the
flange 16 is sufficiently wide, the chamfer 18 is preferably at an
angle of about 45.degree..
After all loose residue and slag from the flame cutting operation
are removed and the prepared bowl is clean, a bolster liner ring 22
which may have an inside diameter of about 14 inches and a height
of 1 1/8 to 1 3/8 inches is positioned coaxially with the bore
center line 21 and located with a tack weld 24. About six tacks
equally spaced are adequate. The liner rings are rolled from
10-gage carbon steel of a composition between A.I.S.I. type 1020
and type 1050, or of low alloy steel having a composition between
A.I.S.I. type 4130 and type 4340.
A liner 26 of like material may be inserted in the bore 20 for the
kingpin as illustrated in FIG. 2. The wall 27 is recessed and the
liner is a press fit within seat 28.
With liner rings 22 and/or 26 in place, the heavy center portion of
the bolster casting is preheated to 150.degree.F. if of Grade `B`
cast steel; 250.degree.F. if Grade `C` cast steel. This reduces the
possibility of cracking.
The bolster is arranged in a horizontal position with the bowl
facing up. To the prepared bolster bowl the bodies of weld metal 30
and 40 as shown in FIG. 3 are added using a fluxless tubular alloy
electrode having a sheath of mild steel and a filler of
approximately the following composition: ferromolybdenum, about
4.5%; ferrochromium, about 17%; ferrosilicon, about 6%;
ferromanganese, about 13%; iron powder, about 59.5%. The filler
comprises approximately 18% by weight of the finished electrode.
The metal is deposited with an electric arc and with a shielding
gas mixture containing 98% argon and 2% oxygen by volume. The first
metal deposited at the apex 32 is laid down in a fast pass with a
wire of about one-sixteenth inch in diameter and after the body 30
has built up to an appreciable extent, a larger wire such as 5/64
or 3/32 in diameter is employed.
Similarly, a body of weld metal 40 is built up at the bore 20. The
entire bolster then is heat treated at a temperature of about
1150.degree.F. for one hour to relieve the stress built up in the
welding process.
With automatic water-cooled equipment such as Chemetron gun model
AM-21 or A-11, the weld metal is deposited in about 2 hours. The
ring 22 and liner 26 require no additional finishing before the
bolster is placed in service.
The analysis of the metal deposited with a shielding gas of 98%
argon and 2% oxygen is shown in column 1 of Table I.
The process can likewise be performed with other gases, for
example, 95% argon, 5% oxygen and argon-carbon dioxide mixtures
containing from about 10% to about 25% carbon dioxide by volume.
Analysis of metal deposited with such mixtures is shown in columns
2 and 3 in Table I. Carbon dioxide may be used as the shielding
gas, but when this is done, the electrode should contain large
percentages of manganese and chromium.
TABLE I ______________________________________ WELD METAL DEPOSIT
______________________________________ 98%A--2%O.sub.2
95%A--5%O.sub.2 75%A--25%CO.sub.2 % C By weight 0.12 0.12 0.12 % Mn
1.52 1.51 1.55 % Si 0.36 0.35 0.31 % Cr 2.11 2.10 2.09 % Mo 0.56
0.55 0.55 Iron Balance Balance Balance Hardness AS Welded .sup.1
38.2R.sub.c 33.2R.sub.c 24.2R.sub.c Hardness Stress Rel. .sup.1
26.1R.sub.c 25.3R.sub.c 18.5R.sub.c
______________________________________ .sup.1 Average of five
readings.
While the invention has been explained with reference to
reconstructing bolsters including preparation of the interior of
the bowl, it will be apparent to those skilled in the art that new
bolsters prepared with a flange cast as shown in FIG. 2 might
suitably be provided with a liner and hard metal alloy deposit as
described above.
While the foregoing invention has been described with respect to
specific embodiments, it will be understood that substitutions and
modifications may be made and all such of these as come within the
spirit of this invention are included within its scope as defined
by the appended claims.
* * * * *