JPS61237386A - Manufacture of compound center electrode for spark plug - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF THE INVENTION The present invention relates to an improved composite center electrode of a silver/base lag having a noble metal firing tip and to a method of manufacturing the same.

Since starch lags are generally used in highly corrosive environments, it is desirable that the center electrode be made of a highly corrosion resistant material such as nickel, nickel alloys, or the like.

It is also desirable that the center electrode contain a highly thermally conductive material in order to expand the operating temperature range of the spacecraft rug. For this reason, it is known to make spark plug center electrodes of the type in which an inner core of a highly thermally conductive material, such as copper, is surrounded by a protective jacket of corrosion-resistant material. It is also known to incorporate noble or semi-precious metals into the tip of the spark plug center electrode to extend life.

Although such precious and semi-precious metals are highly resistant to corrosion at high temperatures in the engine combustion chamber and to attack by spark discharge, they are very expensive and are used during the forming process of the spark plug center electrode. It is necessary to add a few steps to the rounding to be incorporated.

(Prior art) U.S. Patent No. 3. No. 376 discloses a method of manufacturing a composite center electrode for a spark plug. In this method, first, a right cylindrical plate made of a metal with high thermal conductivity such as steel is stacked on top of a right cylindrical plate made of a corrosion-resistant metal such as nickel, and the stacked plates are placed in a die and extruded. This creates a rod with a highly thermally conductive core inside a corrosion-resistant shell. .

U.S. Patent No. 3. ! Hirogu, Hirokuko discloses another method of manufacturing a composite center electrode for a spark plug. First, a right cylindrical billet of corrosion-resistant metal is continuously extruded and drawn to form an elongated cup with a cavity extending therein. Next, a right cylindrical billet of metal with relatively high thermal conductivity is extruded, with a headed portion having a diameter equal to the diameter of the elongated cup and a cavity diameter).
A core is formed, consisting of a protruding portion with a slightly smaller reduced diameter. The protruding part of the core is inserted into the cavity of the cup,
After being press-fitted into the cavity and forming a monolithic rod, it is subjected to a heat diffusion treatment. A head is then formed on the Shirorad by cold working to create a composite center electrode. The elongated cups and cores are individually machined to their respective final dimensions prior to heat diffusion treatment.

U.S. Patent No. 3. No. 3, No. 1 discloses a method for manufacturing a composite center electrode for a spark plug.

First, a right cylindrical billet of corrosion-resistant metal is formed into a cup with a cavity extending therein in a single extrusion step. A right cylindrical billet of metal with high thermal conductivity is then extruded to form a cap consisting of a headed portion with a diameter equal to the diameter of the cup and a protruding portion with a reduced diameter slightly smaller than the diameter of the cavity. molded. The protruding part of one cap is then inserted into the cavity of the cup, and both are extruded through a die to form a rod with a core of uniform diameter inside a shell with uniform wall thickness. Ru. A head is then formed on the Shirorad by cold working to create a composite center electrode.

U.S. Patent No. 3. Gag! ;No. 30 and No. 3.94
7. /Hiroshi? No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, No. 1, 2003, 2003, discloses a Snoke Buddha with a center electrode made of a corrosion-resistant metal. An axial recess is formed in the flared end of the electrode, and a precious metal insert is inserted to fill the recess. The flared end of the center electrode is then swaged to restore the cylindrical shape and retain the noble metal insert within the electrode.

U.S. Patent No. 1. ! Co/, No. 732, No. 1,7g9.0
No. 71, No. 21g Hiroshi 9, 7gg, No. 2,9 Da 3,
No. 293, No. 2,95, Hiroshi? No. J, No. 2, ? j
&, Cococo No. 3, 0 da O, Dali No. 3, No. 3.
! ;41g, No. 239, same No. 3.6 da 3.322,
Same 3rd. Za03.19a, No.3, Za1g, ! ;
! ! ! r, French Patent No. 9,136 and West German Patent No. 1.0! Other related methods and structures are described in Ko, No. 7g1.

OBJECTS AND ARCHITECTURE OF THE INVENTION The present invention relates to a composite center electrode of a S/4-Kudeg having a firing tip made of a noble or semi-noble metal, and to a method of manufacturing the same. First, a right cylindrical billet of corrosion resistant material is formed into a cylindrical cup having an open end and a closed end. When molding the cup, a small conical recess may be molded in the center of the outer surface of the closed end. A right cylindrical billet of highly thermally conductive material is then inserted into the open end of the cup;
It is pressed into a tight fit against the IIa and bottom of the cup, creating a composite billet. A hole is then formed through the conical recess at the closed end of the composite billet, into which an insert made of precious or semi-precious metal is inserted.

The composite billet and precious metal insert are inserted with a tight fit into an extrusion die having an extrusion orifice. Next, a plunger is inserted into the 1st hole, hits the filled end of the composite billet, passes through the extrusion orifice, and extrudes all of the composite billet except for the terminal portion near the filled end, forming a center electrode blank. Ru.

In another embodiment of the invention, a cylindrical cup is first made as described above. A large is then formed at the closed end of the cup. A right cylindrical billet of highly thermally conductive material is then inserted through the open end of the cup and forced into a tight fit against the sides and bottom of the cup cavity to create a composite billet.

An insert made of precious or semi-precious metal is then inserted into the hole and pushed into the hole to form a tight fit. The open end of the cup is molded inward to partially enclose the inner billet. The composite billet and precious metal insert are inserted into the aperture of the die with the extrusion orifice in an interference fit. A plunger is then inserted into the bore of the die,
All but the terminal portion of the composite billet near the filled end is extruded through an extrusion orifice against the filled end of the composite billet to form a center electrode blank. The opposite end of the center electrode blank containing the noble metal insert is formed into a reduced diameter section by a second extrusion. Finally, the opposite end of the center electrode blank is ground to a flat end surface, and its terminal portion is ground to give the center electrode blank the correct longitudinal dimensions.

It is an object of the present invention to provide an improved composite center electrode made of noble or semi-precious metals and having nine firing tips, and a method for making the same.

Other objects and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

(Example) First, with reference to FIGS. 1 to 9, a method for manufacturing an improved composite center electrode of Sunoguchiri Gurag will be described. The manufacturing method and apparatus of the present invention are disclosed in pending U.S. Patent Application No. 17.9.
No. 5A (19g, filed January 2, 2003), the disclosure of which is incorporated herein by reference.

As shown in FIG. 1, extruder 10 includes a composite die 11 positioned above a platen 12. As shown in FIG.

The composite die 11 has a right cylindrical upper part 713 extending downward to the lower die part 15, and the lower guide part 15 is aligned with the dea 13 and has a slightly smaller diameter lower dea 16 passing through it. There is. Is the piston 1 extending through the hole provided in the platen 12 below the composite die 11?
716 and is structurally coupled to the floating protrusion 18 which occupies the entirety of 716.

Upward? A cavity 20 is formed by the @wall of 713 and the upper surface 21 of the floating protrusion 18. If desired, a conical cutout 22 may be formed centrally on the top surface of the floating ejector 18 for purposes described below.

The first step in the method of the invention is to form a right cylindrical billet 23 of corrosion-resistant material into a cup. Billet 23 can be made of nickel or a nickel alloy, which can be formed by drilling or extrusion. In a preferred embodiment, the upper part of the composite die 11 is
Billet 23 is inserted into 713. Billet 23 is
The upper end 25 may be concave or flat, and the straddle 713
It has dimensions to fit within and match its side walls. next,
A plunger 26 with a lower convex surface 27 is inserted into the cavity 21 and impinges on the upper concave surface 25 of the billet 23. Referring to FIG. 2, pressure is applied by plunger 26 to punch billet 23, causing its extrusion to occur at closed end 30. A cup 28 is formed having an open end 31 and a cavity 32 defined by an interior sidewall 33 extending concentrically to a lower concave surface 35 . It can be seen that during the back extrusion process, the conical groove 22 of the floating ejector 18 forms a conical recess 36 in the outer surface of the closed end 30 of the cup.

The next step of the invention is to create a composite billet. Referring to FIG. 3, a right cylindrical billet 37 of high thermal conductivity material is inserted through the open end 31 of the cup 28 in an interference fit. In the preferred embodiment, the billet 37 is made of copper and is pressed into the cavity 32 of the cup 28, with its lower end and cylindrical side wall respectively
It is firmly fitted to the lower concave surface 35 and side wall 33 of B. This step results in a composite billet 38 having a closed end 40 and an open end 41, as shown in FIG. The billet 37 can be shaped so that its end 42 is recessed from the open end 41. Also, the open end 41 can be molded inward so that the copper billet 3f is partially encased within the nickel or nickel alloy cup 28.

The next step of the invention is to add a noble or semi-precious metal insert to the e-composite billet 38. Third
Referring to the figures and FIG. 6, closed end 40 of composite billet 38
A small hole 4 in the area of a conical recess 36 in the center of the outer surface of the
3 is provided.

The holes 43 can be made by drilling or other suitable means. A conical die, portion 36, provided at the closed end 40 allows the hole 4 to be
3, the drill pit and other means can be easily positioned in the correct position. An insert 45 made of noble or semi-precious metal is then inserted into the hole 43. The insert 45 is a strip of wire having the same cross-sectional dimensions as the hole 43 in order to fit into the hole 43 and minimize or eliminate open space. In the illustrated embodiment, only a portion of the insert 45 fits into the hole 43, with the other portion of the insert 45 extending longitudinally outward therefrom, but the insert 45 may fit entirely within the hole 43 if desired. The insert 45 can be made as follows.

In either case, the insert is placed against the bottom of the hole 43. Insert 45 can be made of platinum, iridium, or the like.

The final step of the method of the invention is to create a center electrode blank from the composite billet 38 containing the insert 45. Referring to FIGS. 7 and 3, the extruder 46 is
Above a right cylindrical shape extending downwards to shoulder 50? 748
and an extrusion orifice 5 whose diameter is reduced.
1 and a lower diameter 52 which immediately expands in diameter and passes through the die 47. The diameter of the upper differential 48 is sized to receive the composite billet 38 containing the insert 45 in an interference fit.

The extruder 46 also includes a plunger 53 that has the same diameter as the upper bore 48 and can be inserted into the bore 48 . The plunger 53 may be provided with a shaped end 55 for forming a head or terminal portion 57 on the extruded electrode blank 56, as shown in FIG.

First, the closed end 40 of the composite billet 38 is inserted into the upper gear 48 of the die 47. Pressure is applied to plunger 53 and composite billet 38 is extruded entirely through extrusion orifice 51 except for the distal portion near open end 41 to form electrode blank 56. The electrode blank 56 consists of an unextruded terminal section 57 and a rod section 58 of reduced diameter extending longitudinally therefrom and terminating in a tip 60 as a lower section. Rod portion 58 has a diameter that is the same as the diameter of extrusion orifice 51 and a length that is slightly longer than the length of composite billet 38 . As shown in FIG.
80 and the terminal portion 57 have an elongated inner core of highly thermally conductive material surrounded by an outer protective sheath of corrosion resistant material.

After extrusion, the electrode blank 56 can be removed from the die 47 through the upper gear 48.

Also, since the diameter of the electrode blank 56 is smaller than that of the unextruded composite billet 38, the portion of the insert 45 inserted into the billet is tightened during the extrusion process. The tightening eliminates any open space that remained after insert 45 was inserted into hole 43.

Furthermore, during the extrusion process, a slightly enlarged portion 65 of the insert 45 is created inside the chip 60.

The diameter of this enlarged portion 65 is greater than the diameter of the insert 45 at the end face 61. As a result, the insert 45 is firmly held within the hole 43 and will not fall out.

After the extrusion process is completed, a portion of the insert 45 extends longitudinally out of the tip 60 of the rod portion 58, as shown in FIG. It has been found acceptable to leave this portion of the insert 45 exposed when used in a spring plug. Alternatively, insert 45 can be sized to fit completely within hole 43 prior to extrusion. If the insert 45 is dimensioned correctly, the bottom end surface 61 of the insert 45 should be flush with the bottom end surface 62 of the chip 60, as shown in FIG. Electrode chip 7
At a60, between the cylindrical side wall 64 and the bottom end surface 62,
A small chip z4-6'a may also be provided. taper 63
serves primarily to distinguish between a center electrode with an insert 45 and a normal center electrode;
This is because when 5 is the same color as the surrounding metal, it is difficult to tell apart. The non-extruded terminal portion 5 of the center electrode blank 56 of FIG. Several examples of how to shape terminal portion 57 are disclosed in the previously cited US patent applications, but the methods are not directly relevant to the present invention.

Another method of manufacturing an improved composite center electrode for a spark plug will now be described with reference to FIGS. 70-1g. First, a cup 70 of corrosion resistant material is made as described in FIGS. 1 and 2.

The cup f70 has a closed end 71, an open end 72, and an internal cavity 73.
have. The cavity 73 is defined by a cylindrical inner wall 75 extending along a concentric axis to a lower concave surface 76 .

A conical recess 77 is formed on the outer surface of the closed end 71 of the cup f70. The next step is to provide a hole 78 in the outer surface of the closed end 71 of the cup f70, as shown in FIG. Hole 7B can be formed by drilling, as described above, and as a result of the drilling, end portion 80 with a tip can be formed.

As shown in FIG. 11, first, an interference-fit right cylindrical billet 81 of a highly thermally conductive material, such as copper, is placed on a concentric ring with the cavity 73 - straight line f! - Arranged like an eggplant. Next, the billet 81 is inserted into the cavity 73 from the open end 72 of the cudf 0. As shown in FIG. 72, the length of the billet 81 is slightly shorter than the length of the inner side wall 75, and when inserted into the cavity f 3, the billet 81 is somewhat recessed below the open end 72 of the cuff 70. become. This recess between the open end 72 of the kaddef 0 and the billet 810 allows the billet 8
1 into the cavity 73 of the cup 70, a plunger (not shown) can be easily positioned against the billet 81.

A precious metal or semi-precious metal insert 82 is then coaxially aligned with and inserted into the hole 78, as shown in FIGS. 12 and 13.

The length of the insert 82 is slightly shorter than the length of the hole 78, creating a recessed area between the end of the insert 82 and the closed end 71 of the cuff. Its purpose is the same as described for billet 81.

Billet 81 and insert 82 are then pressed into cavity 73 and hole 78, respectively, to form composite billet 83, as shown in Figure 1. The composite billet 83 is
Closed end 8! s and an open end B6. Billet 81 is
It can be formed to have an end surface 87 recessed from the open end 86. After that, the open end 86t- of the composite billet 83
1 As shown in FIG. 73, the billet 81 can be partially wrapped by molding inside.

The next step in another method of the invention is to
The first step is to extrude the material to make a center electrode blank. This extrusion step can be performed using the conventional extruder 46 described above. As a result of this extrusion process, the center electrode blank 88 shown in FIG. 76 is formed. The electrode blank 88 consists of an unextruded terminal portion 90, a reduced diameter rod portion 91, and a tip portion 92.

Rod portion 91 has the same diameter as the diameter of extrusion orifice 51 and its length is significantly longer than the length of composite billet 83. Enclosed within rod portion 90 is an elongated inner core 93 of high thermal conductivity material made from billet 81 . Since the chip 7'92 of the electrode blank 8B has a smaller diameter than the composite billet 83, the insert is tightened to the chip during the extrusion process. As a result of this tightening,
Enlarged portion 95 of insert 82 within electrode blank 88
I can do it. The diameter of enlarged portion 95 is greater than the diameter of insert 82 at tip 920. As a result, the insert 82 is only retained within the hole 78 and will not fall out. In addition, since the insert 82 is initially recessed into the composite billet 81 before extrusion, as shown in FIG.
The tip 92 of the insert 82 should completely enclose the tip 96 opposite the enlarged portion 950 of the insert 82.

Depending on the size of the insulator into which the electrode blank 88 is inserted, it may be desirable to subject the tip 92 of the electrode blank 88 to a second extrusion step. The chip 92 shown in FIG. 17 was probably extruded through an orifice (not shown) having a slightly smaller diameter than the extrusion orifice 51 used when forming the electrode blank 88. Therefore, the chip f92 is The enlarged portion 95 of the insert 82 is similarly enlarged, with a reduced diameter portion 97t having a smaller diameter than the rod portion 91.

In this second extrusion process, the tip 92 of the electrode blank
and a porcelain insulator (not shown) which ultimately surrounds it.

As is well known, when using a spark plug, the tip 92
A large amount of current flows through. This current generates heat and causes the metal portions of chip 92 to expand. If chip 92 is not subjected to an extrusion process that imparts reduced diameter portion 97,
The chip 92 will expand and strike the relatively unexpandable porcelain insulator surrounding the chip, causing the insulator to fail.

The final step of another method of the present invention is to grind the terminal portion 90 to expose the tip portion 92 of the electrode blank 88. As shown in FIG. 1g, the terminal portion 90 is ground to form a flat shoulder portion 98 and the tip portion 9
2 is ground to a flat end surface 99. These grinding
Any method known in the art may be used and is carried out in such a way that accurate longitudinal dimensions from the shoulder portion 9B to the end surface 99 are obtained.

In other methods of the invention, minor modifications may be made. For example, hole 78 is drilled in billet 8.
1 may be inserted into the cavity 73 of the cup f70. Billet 81 and insert 82 may also be press-fitted into cavity 73 and hole 8, respectively, at different times in the described method. While the principles and methods of carrying out the present invention have been described with reference to preferred embodiments thereof, the present invention may be practiced otherwise than as specifically illustrated and described within the spirit and broad scope thereof. You should understand that you can.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing a right cylindrical billet of corrosion-resistant material placed in a composite die of an extruder prior to the extrusion process. FIG. 2 is a partial cross-sectional view similar to FIG. 1 showing the billet after it has been punched and extruded to form a cup; FIG. 3 is a partial cross-sectional view similar to FIG. A cross-sectional view showing a right cylindrical billet of highly thermally conductive material and an extruded cup. Showing billet,
A cross-sectional view similar to Figure 3, Figure 3 is a cross-sectional view showing the noble metal or semi-precious metal insert before insertion into the hole, and the composite billet of Figure 3 after the closed end hole has been provided, Figure 3. 6
Figure 7 is a cross-sectional view showing the composite billet of Figure 3 after the insert has been inserted into the hole; Figure 7 shows the composite billet of Figure 6 inserted into the die of the extrusion die prior to the extrusion process; Figure g is a partial cross-sectional view similar to Figure 7 showing the composite billet inside the extrusion die after the composite billet has been extruded except for the terminal portion, Figure 9 is a partial cross-sectional view showing the composite billet inside the extrusion die, FIG. 10 is a partial cross-sectional view showing a center electrode modified so that the tip of the center electrode and the bottom surface of the center electrode blank are in the same plane; FIG. , a cross-sectional view showing an extruded cup similar to the cup shown in FIG. 3; FIG. 1/FIG. 1 shows the cup of FIG. Figure 72 shows the billet after it has been inserted into the cavity of the cup and the noble or semi-precious metal insert before it is inserted into the hole. Cross-sectional view N Figure 73 is a cross-sectional view showing the insert after it has been inserted into the hole, Figure 11' is a cross-sectional view similar to Figure 13, showing the insert after it has been press-fitted into the hole, 1st left Figure 76 is a cross-sectional view showing the billet after it has been press-fitted into the cavity of the cup to make the composite billet;
A cross-sectional view showing a center electrode blank formed by extruding the entire composite billet except for the terminal portion shown in the first left figure, and FIG. 17 shows a center electrode blank with two chips.
FIG. 76 is a cross-sectional view similar to FIG. 76 after undergoing a second extrusion process, and FIG. 1g is a cross-sectional view similar to FIG. 17 showing the center electrode blank after the tip and terminal portions have undergone a grinding process. It is. 10... Extruder, 11... Composite goo, 12
...Platen, 13...Upper direction, 15...
Lower part, 16... Lower part, 17...
Piston, 1B...Floating ejector, 20...
Cavity, 21...Top surface, 22...Central conical shape? 23...4-bit V-butt, 25...upper opening surface, 26...plunger, 27...lower convex surface, 28...cup 30...closed end,
31...Open end, 32...Cavity, 33...
Internal side wall, 35... Lower opening surface, 36... Conical recess, 37... Billet, 38... Composite billet, 40... Closed end, 41... Open end, 42
... end face, 43 ... small hole, 45 ... insert, 46 ... extruder, 47 ... goo,
48...Upper der, 50...Shoulder,
51... Extrusion orifice, 52... Lower dea, 53... Delan Sawyer, 55... Shaped end,
56... Electrode blank, 57... Terminal part,
58...Rod part, 60...Tip, 6
1...Bottom end surface of insert, 62...Bottom end surface of tip, 63...Chi/4-165...enlarged part, 70...cup, 71...closed end,
72...Open end, 73...Cavity, 75...
Home fill wall, 7G... lower concave surface, 77...
・Round-shaped recess, 78... Hole, 80... Tapered end, 81... Billet, 82...
・Insert, 83...Composite billet, 85...
・Closed end, 86... Open end, 87... End surface, 8
8...Center electrode! Rank, 9G...Terminal part, 91...Rod part, 92...Tip, 93.
...Inner core, 95...Enlarged part, 96...
Tip of insert, 98...Shoulder part, 99...
・Flat end surface. 2-F' IG, 1 Yo IG, 2-F' IG
, 3 2nd IG, 6 2""F"TG, 7-F'
IG, 8-zoIG, 11-F'IG, 15-zoIG, 17-F'IG, 16-yorIG, 18

Claims (8)

[Claims] (1) (a) Making a composite billet consisting of a cup of corrosion-resistant metal forming a cavity at least partially filled with a material having high thermal conductivity and having a hole in the outer surface of its closed end; (b) inserting at least a portion of a precious metal or semi-precious metal insert into said hole; and (c) extruding the composite billet from said closed end first through an extrusion orifice with an outer sheath of corrosion resistant material. forming a center electrode blank having an encased inner core of highly thermally conductive material and having at least a portion of said insert clamped within its extruded chip; A method for manufacturing a composite center electrode blank for spark plugs. (2) The step of making the composite billet includes forming a conical recess in the outer surface of the closed end of the cup before forming the hole in the outer surface of the closed end of the composite billet. The method according to claim 1. 3. The method of claim 2, wherein the conical recess is formed into the closed end of the cup when the cup is made. 4. A method according to claim 2, characterized in that the formation of the holes in the closed end outer surface of the composite billet takes place in the area of a conical recess formed in the closed end of the cup. (5) The insert is completely in the hole before extrusion, and after extrusion, the insert is in the same plane as the inserted tip of the electrode blank. The method described in Section 1. (6) further comprising forming a reduced diameter section in the tip of the electrode blank by extruding the extruded tip of the electrode blank through a second extrusion orifice having a smaller diameter than the first extrusion orifice. The method according to claim 1. (7) The method further includes the step of molding the extruded tip and the terminal portion of the electrode blank to provide accurate vertical dimensions between the two. the method of. (8) A method according to claim 7, characterized in that said shaping is carried out by grinding.