CA1169237A - Production of electrodes - Google Patents
Production of electrodesInfo
- Publication number
- CA1169237A CA1169237A CA000362279A CA362279A CA1169237A CA 1169237 A CA1169237 A CA 1169237A CA 000362279 A CA000362279 A CA 000362279A CA 362279 A CA362279 A CA 362279A CA 1169237 A CA1169237 A CA 1169237A
- Authority
- CA
- Canada
- Prior art keywords
- cup
- extrusion
- billet
- diameter
- core
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000004519 manufacturing process Methods 0.000 title abstract description 11
- 239000002131 composite material Substances 0.000 claims abstract description 38
- 238000001125 extrusion Methods 0.000 claims abstract description 30
- 239000002184 metal Substances 0.000 claims abstract description 22
- 229910052751 metal Inorganic materials 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 19
- 230000000875 corresponding effect Effects 0.000 claims 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 abstract description 8
- 238000005260 corrosion Methods 0.000 abstract description 6
- 230000007797 corrosion Effects 0.000 abstract description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 abstract description 5
- 229910052802 copper Inorganic materials 0.000 abstract description 5
- 239000010949 copper Substances 0.000 abstract description 5
- 229910052759 nickel Inorganic materials 0.000 abstract description 4
- 229910000990 Ni alloy Inorganic materials 0.000 abstract description 3
- 238000003825 pressing Methods 0.000 abstract description 2
- 238000005482 strain hardening Methods 0.000 description 7
- 238000007667 floating Methods 0.000 description 6
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 2
- 102100038750 Myc-associated zinc finger protein Human genes 0.000 description 1
- 101710146400 Myc-associated zinc finger protein Proteins 0.000 description 1
- 102100026403 Protrudin Human genes 0.000 description 1
- 101710141361 Protrudin Proteins 0.000 description 1
- 230000002730 additional effect Effects 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
- H01T21/00—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs
- H01T21/02—Apparatus or processes specially adapted for the manufacture or maintenance of spark gaps or sparking plugs of sparking plugs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C23/00—Extruding metal; Impact extrusion
- B21C23/22—Making metal-coated products; Making products from two or more metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C33/00—Feeding extrusion presses with metal to be extruded ; Loading the dummy block
- B21C33/004—Composite billet
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21K—MAKING FORGED OR PRESSED METAL PRODUCTS, e.g. HORSE-SHOES, RIVETS, BOLTS OR WHEELS
- B21K1/00—Making machine elements
- B21K1/58—Making machine elements rivets
- B21K1/62—Making machine elements rivets special rivets, e.g. with electrical contacts
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Spark Plugs (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method for producing a composite spark plug electrode is disclos-ed. The method comprises forming a right circular cylindrical billet of a corrosion-resistant metal into a cup having closed and open ends and a cavity having walls extending concentrically therein, and then inserting into the open end of the cup a close-fitting right circular cylindrical billet of a metal having a high thermal conductivity to fit tightly against the walls of the cavity thereof to form a composite billet having closed and filled ends.
The method also includes the steps of inserting the closed end of the compo-site billet into a close-fitting bore of a die having within the bore an extrusion orifice of a diameter less than that of the bore, inserting a plung-er into the bore of the die against the filled end of the composite billet, and applying pressure to the plunger to force all of the composite billet except a terminal portion adjacent to the filled end thereof through the ex-trusion orifice to form an electrode blank having the unextruded terminal portion as an upper headed portion and a rod of reduced diameter extending longitudinally therefrom as a lower portion of a diameter equal to that of the extrusion orifice and a length greater than that of the composite billet.
The cylindrical billet of corrosion-resistant metal can be nickel or nickel alloy and can be formed into the cup by back-extrusion. The cylindrical billet of metal of high thermal conductivity can be copper, and, after being inserted into the cup, can be compressed therein to force a lower end and the cylindrical walls thereof into close-fitting relationship with the cavity of the cup.
A method for producing a composite spark plug electrode is disclos-ed. The method comprises forming a right circular cylindrical billet of a corrosion-resistant metal into a cup having closed and open ends and a cavity having walls extending concentrically therein, and then inserting into the open end of the cup a close-fitting right circular cylindrical billet of a metal having a high thermal conductivity to fit tightly against the walls of the cavity thereof to form a composite billet having closed and filled ends.
The method also includes the steps of inserting the closed end of the compo-site billet into a close-fitting bore of a die having within the bore an extrusion orifice of a diameter less than that of the bore, inserting a plung-er into the bore of the die against the filled end of the composite billet, and applying pressure to the plunger to force all of the composite billet except a terminal portion adjacent to the filled end thereof through the ex-trusion orifice to form an electrode blank having the unextruded terminal portion as an upper headed portion and a rod of reduced diameter extending longitudinally therefrom as a lower portion of a diameter equal to that of the extrusion orifice and a length greater than that of the composite billet.
The cylindrical billet of corrosion-resistant metal can be nickel or nickel alloy and can be formed into the cup by back-extrusion. The cylindrical billet of metal of high thermal conductivity can be copper, and, after being inserted into the cup, can be compressed therein to force a lower end and the cylindrical walls thereof into close-fitting relationship with the cavity of the cup.
Description
This invention relates *o a method for producing a composite spark plug electrode. Methods of producing composite center electrodes are taught by the prior art. United States Patent No. 3,14~,576 granted A~lgust 11, 1964 to Eugen Hagmaier discloses a method for producing a composite center electrode by superposing a right circular cylindrical plate of a metal of a good thermal conductivity, such as copper, on a right circular cylindrical plate of corrosion-resistant metal, such as nickel, within a die and extrud-ing the plates therethrough to form a rod having a core of good thermal con-ductivity within a corrosion-resistant shell. The primary disadvantage of this method is that the length of the rod is limited because the core is formed with a taper which causes a correspondingly reduced thickness in walls of the shell as the metal plates are being extruded. This makes it impossible to assure uniform heat conductivity.
United States Patent No. 3,548,472 granted December 22, 1970 to ~isashi Urushiwara discloses a method for producing a composite center elec-trode by subjecting a right circular cylindrical billet of corrosion-resis-tant metal to successive extrusions and drawings to form an elongated cup having a cavity extending therein, extruding a right circular cylindrical billet of a metal of a relatively higher thermal conductivity to form a core having a headed portion with a diameter equal to that of the elongated cup and a protrudin~ portion of reduced diameter slightly less than that of the cavity, inserting the protruding portion of the core into the cavity and pressing the core therein to form an i.ntegral rod which is then subjected to heat diffusion. A composite center electrode is then formed by cold working the rod to form a head thereon. Both the elongated cup and the core are worked separately to dimensions substantially the same as their final dimen-sions before heat diffusion. Although this method produces a rod having a ~ ~ ~9~37 core of uniform diameter within a shell having walls of uniform thickness, the use of successive extrusions and drawings to form the elongated cup is uneconomical for mass production.
United States Patent No. 3,857,147 granted December 31, 1~74 to Terumoto Yamaguchi teaches a method for producing a composite center elec-trode by subjecting a right circular cylindrical billet of corrosion-resis-tant metal to only one extrusion step to form a cup having a cavity extend-ing therein, extruding a right circular cylindrical billet of a metal of a good thermal conductivity to form a cap having a headed portion with a dia-meter equal to that of the cup and a protruding portion of reduced diameter slightly less than that of the cavity, inserting the protruding portion of the cap into the cavity of the cup, superposing the cap on the cup within a die and extruding both therethrough to form a rod having a core of uniform diameter within a shell having walls of uniform thickness. A composite center electrode is then formed by cold working the rod to form a head there-on. Although the cup and the cap are worked separately, they are not worked to their final dimensions until both are extruded together. Hence, the total number of cold working steps is reduced to make mass production more fea~ible.
It is an object of the invention to provide a method for producing a composite spark plug electrode by a reduced number of cold working steps to make mass production thereof more economically feasible.
It is a further object of the invention to provide a method for producing a composite spark plug electrode in which only one step is requir-ed to form a composite billet into an electrode blank having both an upper headed portion and a lower portion of reduced diameter extending longitudi-nally therefrom, that is suitable for use as a composite spark plug electrode.
( ~ J ~9~37 l'he invention provides a method of forming a bimetal electrode having a shank of substantiall~ constant diameter Y
extending from a first end to an opposed, radially enlarged head having a diameter of X, where Y is less than X, said method com-prising forming a slug of a first metal into a cup having a diameter of at least X, a closed end, an open end and a tubular portion with a central cavity therein extending a distanca of Z
from said open end to said closed end, forming a cylindrical core having a volume substantially equal to but not sreater than that of the central cavi~y from a different metal, inserting the cylindrical core into said central opening to form a composite billet having first and second ends corresponding, respectively, with the closed and open ends of the cup wherein said core does not project beyond said open end, extruding a portion of said : composite billet, first end firstt through an extrusion:orifice of a die, said orifice having a diameter of Y, and terminating said extrusion while a portion of said cup remains unextruded having a diameter of at least X. The electrode blank is suitable for use as a composite spark plug electrode, but the upper headed portion thereof can be shaped into a more desirable electrode head con-figuration.
To assure that the rod of the composite center electrode has a core of uniform diameter within a shell having walls of uniform thickness, the Urushiwara and Yamaguchi patents expanded the Hagmaier patent to include the separate working of the billet of corrosion-resistant metal and the billet of metal of good thermal conductivity. The latter step of separately working or , ~ 1 6~3~
extruding the billet of metal of good thermal conductivit~ to form a core, in the case of the Urushiwara patent, and a cap, in the case of the - .
.
i , ' ~
- ' .
..
- 3a ~
' i ~ 69 ~ 3 ~
Yamaguchi patent, each having a headed and protruding portion, has been elimina~ed by the instant invention. The right circular cylindrical billet is not worked separately at all, but simply inserted into the open end of the cup to form a composite billet which is then extruded. To form the com-posite center electrode, the ~rushiwara and Yamaguchi patents each include the step of cold working the rod to form the head thereon. The instant in vention eliminates this step by extruding all but the terminal portion of the composite billet to form the upper headed portion of the electrode blank.
Even though the electrode blank is suitable for use as a composite spark plug electrode, additional cold working can be used to shape the headed portion thereof into a more desirable electrode head configura~ion.
In the accompanying drawings:-; Figure 1 is a partially schematic, vertical sectional view show-ing a right circular cylindrical billet of corrosion-resistant metal after being sized and then inserted into a cavity of a die wherein the cavity has closed and open ends.
Figure 2 is a sectional view showing the billet of Figure 1 after being pierced and back-extruded to form a cup having closed and open ends and a cavi~y extending concentrically therein.
; 20 ~igure 3 is a sectional view showing the billet of Figure 1 after being inserted into a cavity of a die wherein the cavity has closed and open ends and a chamferred surface adjacent to the closed end thereof.
Figure 4 is a sectional view showing the billet of Figure 3 after being pierced and back extruded to form a cup having closed and open ends, a chamferred edge adjacent to the closed end thereof~ and a cavity extending concentrically therein.
Figure 5 is a partially schematic, vertical sectional view showing i _ ~ _ 1 3 ~ 9 2 3 17 the cup of Figure ~ and a right circular cylindrical billet of metal of high thermal conductivity prior to being inserted into the cavity of the cup.
Figure 6 is a sectional view showing the billet of Figure 5 after being inserted into the cavity of the cup and compressed therein to form a composite billet having filled and closed ends and a chamferred edge adjacent to the closed end thereof.
Figure 7 is a partially schematic, vertical sectional view showing the composite billet of Figure 6 after the closed end thereof is inserted within a close-fitting bore of a die having within the bore an extrusion orifice.
Figure 8 is a sectional view showing the composite billet of Figure 7 after a plunger is inserted into the bore of the dic against the filled end of the composite billet and after pressure is applied to the plunger to force all the composite billet except a terminal portion adjacent to the filled and thereof through the extrusion orifice to form an electrode blank having the unextruded terminal portion as an upper headed portion.
Figure 9 is a partially schematic, vertically sectional view show-ing the electrode blank of Figure 8.
Figure 10 is a sectional view showing the electrode blank of Figure 9 after the upper headed portion is reduced in diameter.
~igure 11 is a sectional view showing the electrode blank of Figure 10 after the upper héaded portion of reduced diameter is subjected to addi-tional heading.
Referring now in more detail to the drawings, and, in particular to Figure 1, a back-extruder indicated generally at 10 comprises a die 1]
positioned on a platen 12 and having a right circular bore 13 extending there-through, a piston 1~ extending through the platen 12 in structural relation-1 1 ~9~7 ship with a floating ejector 15 which closes a lower opening of the bore 13, and a plunger 16 of smaller diameter than and insertable into an upper open-ing of the bore 13. A cavity indicated generally at 17 is formed by walls of the bore ].3 and an upper surface 18 of the floating ejector 15.
The first step of the method involves the formation o a right circular cylindrical billet of a corrosion-Iesistant metal into a cup. The billet can be nickel or nickel alloy which can be formed by drilling or back-extrusion. In the preferred embodiment, a right circular cylindrical billet 19 of nickel alloy is formed into a cup by a back-extrusion step which com-prises the following sub-steps. m e billet 19 having an upper concave end 20 is sized to fit tightly against the walls of the kore 13 cmd a convex face 21 of the plunger 16 and is superposed on the upper surface 18 of the float-ing ejector 15. 'rhe plunger 16 is then inserted into the cavity 17 against the upper concave end 20 of the billet 19. Referring to Pigure 2, pressure is applied to the plunger 16 which pierces the billèt l9 ~See Figure 1) and causes back-extrusion thereof to form a cup 22 having closed and open ends 23 and 24 and a cavity indicated generally at 25 with walls 26 extending con-centrically therein to a lower concave surface 27. After the plunger 16 is extracted from the cavity 25 of the cup 22~ pressure is applied to the piston 14 which causes the floating ejector 15 to Eorce the cup 22 out of the cavity 17 of the die ll.
Referring to Figure 3, another back-extruder indicated generally at 28 is similar to the back-extruder lO in Figure 1 and comprises a compo-site die 29 positioned on the platen 12 and having a right circular upper bore 30 extending therein *o a chamferred shoulder 31 reducing in diameter to a lower bore 32 extending therethrough, the piston 14 extending through the platen 12 in structural relationship with a floating ejector 33 which fills t J 6~3~
the lower bore 32, and the plunger 16 of smaller diameter than and insertable into the upper bore 30. A cavity indicated generally at 34 is ormed by walls of the upper bore 30, an upper surface 35 of the floating ejector 33, and walls of the chamferred shoulder 31 extending therebetween. In ~he preferred embodiment, the back-extrusion step discussed hereinabove is accomplished in this back-extruder 28 rather than the other. The billet 19 is sized to fit tightly against the walls of the upper bore 30 and is seated on the chamferr-ed shoulder 31 therein. After the plunger 16 is inserted into the cavity 34, and referring to Figure 4, the plunger 16 pierces ~he billet 19 ~See Figure 3) to form a cup 36 having closed and open ends 37 and 38, a chamferr-ed edge 39 adjacent to the closed end 37 thereofl and a cavi~y lndicated generally at 40 having walls 41 extending concentrically therein to a lower concave surface 42.
The next step of the method involves the formation of a com-posite billet. Referring to Figure 5, a close-fitting right circular cylin-drical billet 43 of a metal having a high thermal conductivity is inserted, as indicated by an arrow, into the open end 37 of the cup 36 to fit tightly against the walls 41 o the cavity 40 thereof to form a composite billet. In the preferred embodiment, the billet 43 is copper and is , compressed within the cavity 40 of the cup 36 to force a lower end 44 and the cylindrical walls thereof into close-fitting relationship with the lower concave surface 42 and the walls 41 of the cavity 40 of the cup 36.
This step forms a composit0 billet indicated generally at 45 in Figure 6 having closed and filled ends 46 and 47 and a chamferred edge 48 adjacent to the closed end 46 thereof. The purpose of forming an edge adjacent to the closed end 46 of the composite billet 45 is to guide a composite billet 45 as it is forced through a forward-extruder. Hence, the chamferred edge 48 can be of any other configuration sufficient to accomplish that pur-1 .1 ~9~3'~
pose.
The final step of the method involves the formation of an electrode blank from the composite billet 45. Referring to Pigure 7, a forward-extrud-er indicated generally at 49 comprises a die 50 having a right circular upper bore 51 extending therein to a concave shoulder 52 reducing in diameter to form an extrusion orifice 53 which then enlarges in diameter to a lower bore 54 extending therethrough. The upper bore 51 has a diameter sufficiently large to receive the composite billet 45 in a close-fitting relationship.
The forward-extruder 49 also comprises a plunger 55 having a diameter equal to that of the upper bore 51 and insertable therein~ and a stud 56 extending concentrically from a lower end thereo~. The stud 56 has a diameter equal to that of the copper billet 43 ~see Figure 5) and a depth no greater than one hal the diameter thereof.
In the preferred embodiment, the closed end 46 of the composite billet 45 is inserted into the upper bore 51 of the die 50. The plunger 55 is then inserted into the upper bore 51 of the die 50 against the filled end 47 of the composite billet 45. Referring to Figure 8~ pressure is appli-ed to the plunger 55 which forces all of the composite billet 45 except a terminal portion adjacent to the filled end 47 thereof through the extrusion orifice 53 of the die 50 to form an electrode blank indicated generally at 57 having the unextruded terminal por~ion as an upper headed portion 58 and a rod 59 of reduced diameter extending longitudinally therefrom as a lower portion of a diameter equal to that of the extrusion orifice 53 and a length greater than that of the composite billet 45 (See Figure 7). The electrode blank 57 is then removed from the die 50 through the upper bore 51 thereof.
The rod 59 of the electrode blank 57 has a core 60 of sufficient-ly uniform diameter within a shell 61 having walls of sufficiently uniform 7 ~ ~9~37 thickness to assure uniform heat conductivity. Even though the electrode blank 57 is suitable for use as a composite spark plug electrode, a specific application sometimes necessitates the additional step of shaping the upper headed portion 58 of the electrode blank 57 into a more desirable electrode head configuration. For example, the upper headed portion 58 of the electrode blank 57 in Figure 9 comprises an under head 62 formed by the concave surface of the shoulder 52 of the die 50, a side head 63 formed by walls of the upper bore 51 of the die 50, and a recessed upper core surface 64 of copper concen-tric within a stepped lip 65 of nickel and formed by the stud 56 extending from the lower surface of the plunger 55 (see Figures 7 and 8).
In the preferred embodiment, the side head 63 of the upper headed portion 58 of the electrode blank 57 is reduced in diameter by cold working to form an upper headed portion 58' of an electrode blank 57' having a cham-ferred under head 62' of reduced diameter, a side head 63' of reduced dia-meter and increased height, and a recessed upper core surface 64' of reduced diameter concentric with a rounded lip 55' of reduced diameter as illustrat-ed in Figure 10. The under head 62' and the rounded lip 65' of the upper headed portion 5&' are then flattened to form an upper headed por~ion 58"
of a composite spark plug electrode 57" having a chamferred under head 62"
of a reduced angle, a side head 63" of reduced height, and a recessed upper core surface 64" of reduced diameter concentric with a round lip ~5" flatten-ed to substantially cover the upper core surface 64" as illustrated in Figure ll. The composite spark plug electrode 57" is now suitable for the specific application referred to above.
United States Patent No. 3,548,472 granted December 22, 1970 to ~isashi Urushiwara discloses a method for producing a composite center elec-trode by subjecting a right circular cylindrical billet of corrosion-resis-tant metal to successive extrusions and drawings to form an elongated cup having a cavity extending therein, extruding a right circular cylindrical billet of a metal of a relatively higher thermal conductivity to form a core having a headed portion with a diameter equal to that of the elongated cup and a protrudin~ portion of reduced diameter slightly less than that of the cavity, inserting the protruding portion of the core into the cavity and pressing the core therein to form an i.ntegral rod which is then subjected to heat diffusion. A composite center electrode is then formed by cold working the rod to form a head thereon. Both the elongated cup and the core are worked separately to dimensions substantially the same as their final dimen-sions before heat diffusion. Although this method produces a rod having a ~ ~ ~9~37 core of uniform diameter within a shell having walls of uniform thickness, the use of successive extrusions and drawings to form the elongated cup is uneconomical for mass production.
United States Patent No. 3,857,147 granted December 31, 1~74 to Terumoto Yamaguchi teaches a method for producing a composite center elec-trode by subjecting a right circular cylindrical billet of corrosion-resis-tant metal to only one extrusion step to form a cup having a cavity extend-ing therein, extruding a right circular cylindrical billet of a metal of a good thermal conductivity to form a cap having a headed portion with a dia-meter equal to that of the cup and a protruding portion of reduced diameter slightly less than that of the cavity, inserting the protruding portion of the cap into the cavity of the cup, superposing the cap on the cup within a die and extruding both therethrough to form a rod having a core of uniform diameter within a shell having walls of uniform thickness. A composite center electrode is then formed by cold working the rod to form a head there-on. Although the cup and the cap are worked separately, they are not worked to their final dimensions until both are extruded together. Hence, the total number of cold working steps is reduced to make mass production more fea~ible.
It is an object of the invention to provide a method for producing a composite spark plug electrode by a reduced number of cold working steps to make mass production thereof more economically feasible.
It is a further object of the invention to provide a method for producing a composite spark plug electrode in which only one step is requir-ed to form a composite billet into an electrode blank having both an upper headed portion and a lower portion of reduced diameter extending longitudi-nally therefrom, that is suitable for use as a composite spark plug electrode.
( ~ J ~9~37 l'he invention provides a method of forming a bimetal electrode having a shank of substantiall~ constant diameter Y
extending from a first end to an opposed, radially enlarged head having a diameter of X, where Y is less than X, said method com-prising forming a slug of a first metal into a cup having a diameter of at least X, a closed end, an open end and a tubular portion with a central cavity therein extending a distanca of Z
from said open end to said closed end, forming a cylindrical core having a volume substantially equal to but not sreater than that of the central cavi~y from a different metal, inserting the cylindrical core into said central opening to form a composite billet having first and second ends corresponding, respectively, with the closed and open ends of the cup wherein said core does not project beyond said open end, extruding a portion of said : composite billet, first end firstt through an extrusion:orifice of a die, said orifice having a diameter of Y, and terminating said extrusion while a portion of said cup remains unextruded having a diameter of at least X. The electrode blank is suitable for use as a composite spark plug electrode, but the upper headed portion thereof can be shaped into a more desirable electrode head con-figuration.
To assure that the rod of the composite center electrode has a core of uniform diameter within a shell having walls of uniform thickness, the Urushiwara and Yamaguchi patents expanded the Hagmaier patent to include the separate working of the billet of corrosion-resistant metal and the billet of metal of good thermal conductivity. The latter step of separately working or , ~ 1 6~3~
extruding the billet of metal of good thermal conductivit~ to form a core, in the case of the Urushiwara patent, and a cap, in the case of the - .
.
i , ' ~
- ' .
..
- 3a ~
' i ~ 69 ~ 3 ~
Yamaguchi patent, each having a headed and protruding portion, has been elimina~ed by the instant invention. The right circular cylindrical billet is not worked separately at all, but simply inserted into the open end of the cup to form a composite billet which is then extruded. To form the com-posite center electrode, the ~rushiwara and Yamaguchi patents each include the step of cold working the rod to form the head thereon. The instant in vention eliminates this step by extruding all but the terminal portion of the composite billet to form the upper headed portion of the electrode blank.
Even though the electrode blank is suitable for use as a composite spark plug electrode, additional cold working can be used to shape the headed portion thereof into a more desirable electrode head configura~ion.
In the accompanying drawings:-; Figure 1 is a partially schematic, vertical sectional view show-ing a right circular cylindrical billet of corrosion-resistant metal after being sized and then inserted into a cavity of a die wherein the cavity has closed and open ends.
Figure 2 is a sectional view showing the billet of Figure 1 after being pierced and back-extruded to form a cup having closed and open ends and a cavi~y extending concentrically therein.
; 20 ~igure 3 is a sectional view showing the billet of Figure 1 after being inserted into a cavity of a die wherein the cavity has closed and open ends and a chamferred surface adjacent to the closed end thereof.
Figure 4 is a sectional view showing the billet of Figure 3 after being pierced and back extruded to form a cup having closed and open ends, a chamferred edge adjacent to the closed end thereof~ and a cavity extending concentrically therein.
Figure 5 is a partially schematic, vertical sectional view showing i _ ~ _ 1 3 ~ 9 2 3 17 the cup of Figure ~ and a right circular cylindrical billet of metal of high thermal conductivity prior to being inserted into the cavity of the cup.
Figure 6 is a sectional view showing the billet of Figure 5 after being inserted into the cavity of the cup and compressed therein to form a composite billet having filled and closed ends and a chamferred edge adjacent to the closed end thereof.
Figure 7 is a partially schematic, vertical sectional view showing the composite billet of Figure 6 after the closed end thereof is inserted within a close-fitting bore of a die having within the bore an extrusion orifice.
Figure 8 is a sectional view showing the composite billet of Figure 7 after a plunger is inserted into the bore of the dic against the filled end of the composite billet and after pressure is applied to the plunger to force all the composite billet except a terminal portion adjacent to the filled and thereof through the extrusion orifice to form an electrode blank having the unextruded terminal portion as an upper headed portion.
Figure 9 is a partially schematic, vertically sectional view show-ing the electrode blank of Figure 8.
Figure 10 is a sectional view showing the electrode blank of Figure 9 after the upper headed portion is reduced in diameter.
~igure 11 is a sectional view showing the electrode blank of Figure 10 after the upper héaded portion of reduced diameter is subjected to addi-tional heading.
Referring now in more detail to the drawings, and, in particular to Figure 1, a back-extruder indicated generally at 10 comprises a die 1]
positioned on a platen 12 and having a right circular bore 13 extending there-through, a piston 1~ extending through the platen 12 in structural relation-1 1 ~9~7 ship with a floating ejector 15 which closes a lower opening of the bore 13, and a plunger 16 of smaller diameter than and insertable into an upper open-ing of the bore 13. A cavity indicated generally at 17 is formed by walls of the bore ].3 and an upper surface 18 of the floating ejector 15.
The first step of the method involves the formation o a right circular cylindrical billet of a corrosion-Iesistant metal into a cup. The billet can be nickel or nickel alloy which can be formed by drilling or back-extrusion. In the preferred embodiment, a right circular cylindrical billet 19 of nickel alloy is formed into a cup by a back-extrusion step which com-prises the following sub-steps. m e billet 19 having an upper concave end 20 is sized to fit tightly against the walls of the kore 13 cmd a convex face 21 of the plunger 16 and is superposed on the upper surface 18 of the float-ing ejector 15. 'rhe plunger 16 is then inserted into the cavity 17 against the upper concave end 20 of the billet 19. Referring to Pigure 2, pressure is applied to the plunger 16 which pierces the billèt l9 ~See Figure 1) and causes back-extrusion thereof to form a cup 22 having closed and open ends 23 and 24 and a cavity indicated generally at 25 with walls 26 extending con-centrically therein to a lower concave surface 27. After the plunger 16 is extracted from the cavity 25 of the cup 22~ pressure is applied to the piston 14 which causes the floating ejector 15 to Eorce the cup 22 out of the cavity 17 of the die ll.
Referring to Figure 3, another back-extruder indicated generally at 28 is similar to the back-extruder lO in Figure 1 and comprises a compo-site die 29 positioned on the platen 12 and having a right circular upper bore 30 extending therein *o a chamferred shoulder 31 reducing in diameter to a lower bore 32 extending therethrough, the piston 14 extending through the platen 12 in structural relationship with a floating ejector 33 which fills t J 6~3~
the lower bore 32, and the plunger 16 of smaller diameter than and insertable into the upper bore 30. A cavity indicated generally at 34 is ormed by walls of the upper bore 30, an upper surface 35 of the floating ejector 33, and walls of the chamferred shoulder 31 extending therebetween. In ~he preferred embodiment, the back-extrusion step discussed hereinabove is accomplished in this back-extruder 28 rather than the other. The billet 19 is sized to fit tightly against the walls of the upper bore 30 and is seated on the chamferr-ed shoulder 31 therein. After the plunger 16 is inserted into the cavity 34, and referring to Figure 4, the plunger 16 pierces ~he billet 19 ~See Figure 3) to form a cup 36 having closed and open ends 37 and 38, a chamferr-ed edge 39 adjacent to the closed end 37 thereofl and a cavi~y lndicated generally at 40 having walls 41 extending concentrically therein to a lower concave surface 42.
The next step of the method involves the formation of a com-posite billet. Referring to Figure 5, a close-fitting right circular cylin-drical billet 43 of a metal having a high thermal conductivity is inserted, as indicated by an arrow, into the open end 37 of the cup 36 to fit tightly against the walls 41 o the cavity 40 thereof to form a composite billet. In the preferred embodiment, the billet 43 is copper and is , compressed within the cavity 40 of the cup 36 to force a lower end 44 and the cylindrical walls thereof into close-fitting relationship with the lower concave surface 42 and the walls 41 of the cavity 40 of the cup 36.
This step forms a composit0 billet indicated generally at 45 in Figure 6 having closed and filled ends 46 and 47 and a chamferred edge 48 adjacent to the closed end 46 thereof. The purpose of forming an edge adjacent to the closed end 46 of the composite billet 45 is to guide a composite billet 45 as it is forced through a forward-extruder. Hence, the chamferred edge 48 can be of any other configuration sufficient to accomplish that pur-1 .1 ~9~3'~
pose.
The final step of the method involves the formation of an electrode blank from the composite billet 45. Referring to Pigure 7, a forward-extrud-er indicated generally at 49 comprises a die 50 having a right circular upper bore 51 extending therein to a concave shoulder 52 reducing in diameter to form an extrusion orifice 53 which then enlarges in diameter to a lower bore 54 extending therethrough. The upper bore 51 has a diameter sufficiently large to receive the composite billet 45 in a close-fitting relationship.
The forward-extruder 49 also comprises a plunger 55 having a diameter equal to that of the upper bore 51 and insertable therein~ and a stud 56 extending concentrically from a lower end thereo~. The stud 56 has a diameter equal to that of the copper billet 43 ~see Figure 5) and a depth no greater than one hal the diameter thereof.
In the preferred embodiment, the closed end 46 of the composite billet 45 is inserted into the upper bore 51 of the die 50. The plunger 55 is then inserted into the upper bore 51 of the die 50 against the filled end 47 of the composite billet 45. Referring to Figure 8~ pressure is appli-ed to the plunger 55 which forces all of the composite billet 45 except a terminal portion adjacent to the filled end 47 thereof through the extrusion orifice 53 of the die 50 to form an electrode blank indicated generally at 57 having the unextruded terminal por~ion as an upper headed portion 58 and a rod 59 of reduced diameter extending longitudinally therefrom as a lower portion of a diameter equal to that of the extrusion orifice 53 and a length greater than that of the composite billet 45 (See Figure 7). The electrode blank 57 is then removed from the die 50 through the upper bore 51 thereof.
The rod 59 of the electrode blank 57 has a core 60 of sufficient-ly uniform diameter within a shell 61 having walls of sufficiently uniform 7 ~ ~9~37 thickness to assure uniform heat conductivity. Even though the electrode blank 57 is suitable for use as a composite spark plug electrode, a specific application sometimes necessitates the additional step of shaping the upper headed portion 58 of the electrode blank 57 into a more desirable electrode head configuration. For example, the upper headed portion 58 of the electrode blank 57 in Figure 9 comprises an under head 62 formed by the concave surface of the shoulder 52 of the die 50, a side head 63 formed by walls of the upper bore 51 of the die 50, and a recessed upper core surface 64 of copper concen-tric within a stepped lip 65 of nickel and formed by the stud 56 extending from the lower surface of the plunger 55 (see Figures 7 and 8).
In the preferred embodiment, the side head 63 of the upper headed portion 58 of the electrode blank 57 is reduced in diameter by cold working to form an upper headed portion 58' of an electrode blank 57' having a cham-ferred under head 62' of reduced diameter, a side head 63' of reduced dia-meter and increased height, and a recessed upper core surface 64' of reduced diameter concentric with a rounded lip 55' of reduced diameter as illustrat-ed in Figure 10. The under head 62' and the rounded lip 65' of the upper headed portion 5&' are then flattened to form an upper headed por~ion 58"
of a composite spark plug electrode 57" having a chamferred under head 62"
of a reduced angle, a side head 63" of reduced height, and a recessed upper core surface 64" of reduced diameter concentric with a round lip ~5" flatten-ed to substantially cover the upper core surface 64" as illustrated in Figure ll. The composite spark plug electrode 57" is now suitable for the specific application referred to above.
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of forming a bimetal electrode having a shank of substantially constant diameter Y extending from a first end to an opposed, radially enlarged head having a diameter of X, where Y is less than X, said method comprising forming a slug of a first metal into a cup having a diameter of at least X, a closed end, an open end and a tubular portion with a central cavity therein extending a distance of Z from said open end to said closed end, forming a cylindrical core having a volume substantially equal to but not greater than that of the central cavity from a different metal, inserting the cylindrical core into said central opening to form a composite billet having first and second ends correspond-ing, respectively, with the closed and open ends of the cup where-in said core does not project beyond said open end, extruding a portion of said composite billet, first end first, through an extrusion orifice of a die, said orifice having a diameter of Y, and terminating said extrusion while a portion of said cup remains unextruded having a diameter of at least X.
2. A method as claimed in claim 1 wherein said slug is formed into said cup by a back-extrusion step.
3. A method as claimed in claim 1 wherein said cup, prior to extrusion, and the unextruded portion of said cup have diameters greater than X and wherein, after extrusion, the diameter of the latter is reduced to X.
4. A method as claimed in claim 1 wherein, prior to extrusion, the cup and the core are forced into close-fitting engagement.
5. A method as claimed in claim 3 wherein, prior to extrusion, the cup and the core are forced into close-fitting engagement.
6. A method as claimed in claim 1, 2 or 5 wherein, during extrusion, substantial contact is maintained between said core and said cup by the forces of extrusion.
7. A method as claimed in claim 3 wherein, during extrusion, substantial contact is maintained between said core and said cup by the forces of extrusion.
8. A method as claimed in claim 4 wherein, during extrusion, substantial contact is maintained between said core and said cup by the forces of extrusion.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US8459679A | 1979-10-15 | 1979-10-15 | |
| US84,596 | 1979-10-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1169237A true CA1169237A (en) | 1984-06-19 |
Family
ID=22185990
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000362279A Expired CA1169237A (en) | 1979-10-15 | 1980-10-14 | Production of electrodes |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5663789A (en) |
| BE (1) | BE885672A (en) |
| CA (1) | CA1169237A (en) |
| DE (1) | DE3036226A1 (en) |
| FR (1) | FR2467497A1 (en) |
| GB (1) | GB2060454B (en) |
| IT (1) | IT1143198B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2076706B (en) * | 1980-05-30 | 1984-06-27 | Champion Spark Plug Co | Producing a composite center electrode |
| EP0044764A1 (en) * | 1980-07-17 | 1982-01-27 | Bendix Autolite Corporation | Method for manufacturing a center electrode for use in a spark plug |
| US4695759A (en) * | 1981-10-29 | 1987-09-22 | Champion Spark Plug Company | Method for producing a composite center electrode and an electrode |
| JPS58225588A (en) * | 1982-06-24 | 1983-12-27 | 日本特殊陶業株式会社 | Method of producing central electrode of ignition plug |
| US4684352A (en) * | 1985-03-11 | 1987-08-04 | Champion Spark Plug Company | Method for producing a composite spark plug center electrode |
| JP2012084389A (en) * | 2010-10-12 | 2012-04-26 | Ngk Spark Plug Co Ltd | Method of manufacturing central electrode for spark plug, and method of manufacturing spark plug |
| JP5279870B2 (en) * | 2011-01-27 | 2013-09-04 | 日本特殊陶業株式会社 | Spark plug electrode manufacturing method and spark plug manufacturing method |
| JP5639118B2 (en) | 2012-06-05 | 2014-12-10 | 日本特殊陶業株式会社 | Manufacturing method of spark plug |
| WO2020223413A1 (en) | 2019-04-30 | 2020-11-05 | Federal-Mogul Ignition Llc | Spark plug electrode and method of manufacturing same |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2955222A (en) * | 1958-06-25 | 1960-10-04 | Bosch Gmbh Robert | Center electrode structure for spark plugs and process for making the same |
| US3144576A (en) * | 1962-02-14 | 1964-08-11 | Hagmaier Eugen | Spark plug and method of manufacture |
| GB1011486A (en) * | 1963-01-09 | 1965-12-01 | Heinz Teves | Improvements in or relating to mushroom valves |
| US3548472A (en) * | 1967-11-15 | 1970-12-22 | Hitachi Ltd | Ignition plug and method for manufacturing a center electrode for the same |
| JPS48103445A (en) | 1972-04-14 | 1973-12-25 | ||
| GB2037190B (en) * | 1978-12-16 | 1982-08-25 | Gkn Floform Ltd | Manufacture of spark plug electrode |
-
1980
- 1980-09-11 GB GB8029395A patent/GB2060454B/en not_active Expired
- 1980-09-25 DE DE19803036226 patent/DE3036226A1/en active Granted
- 1980-10-09 FR FR8021613A patent/FR2467497A1/en active Granted
- 1980-10-13 IT IT49882/80A patent/IT1143198B/en active
- 1980-10-13 JP JP14285280A patent/JPS5663789A/en active Granted
- 1980-10-13 BE BE0/202437A patent/BE885672A/en not_active IP Right Cessation
- 1980-10-14 CA CA000362279A patent/CA1169237A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5663789A (en) | 1981-05-30 |
| DE3036226A1 (en) | 1981-04-23 |
| DE3036226C2 (en) | 1990-06-28 |
| GB2060454B (en) | 1983-09-14 |
| BE885672A (en) | 1981-04-13 |
| FR2467497A1 (en) | 1981-04-17 |
| JPS6349356B2 (en) | 1988-10-04 |
| FR2467497B1 (en) | 1983-04-15 |
| GB2060454A (en) | 1981-05-07 |
| IT8049882A0 (en) | 1980-10-13 |
| IT1143198B (en) | 1986-10-22 |
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