US2716267A - Machine for assembling spark plug electrodes - Google Patents

Description

Aug. 30, 1955 R. K. CHRISTIE ETAL 2,716,267

MACHINE FOR ASSEMBLING SPARK PLUG ELECTRODES Filed June 1, 1951 5 Sheets-Sheet l TIE-1' /0 {56 i 7 16 3115 if jg 15 TIE-Z- Bnventors: P0521: T K. CHRIS TIE,

CARL J .FATUN..

(Ittomegs Aug. 30, 1955 R. K. CHRISTIE ETAL MACHINE FOR ASSEMBLING SPARK PLUG ELECTRODES 3 Sheets-Sheet 2 Filed June 1, 1951 Snnentors: QUE/EFT K. CHHIS' TIE EARL JEATUA". @J-u. Q @114 (Zttomeg:

30, 1955 R. K. CHRISTIE HAL 2,716,267

MACHINE FOR ASSEMBLING SPARK PLUG ELECTRODES Filed June 1, 1951 5 Sheets-Sheet 3 Z'nwentors EUBBET K. EHHJE TIE,

EARL JEATJN.

QMQW

(Ittornegs United States Patent MACHINE FOR ASSEMBLENG SPARK PLUG ELECTRODES Robert K. Christie and Carl 3. Eaton, Toledo, Ohio, as-

signors to Champion Spark Plug Company, Toledo, Ohio, a corporation of Delaware Application June 1, 1951, Serial No. 229,476

Claims. (Cl. 29-25.19)

This invention relates to the assembly of spark plugs for internal combustion engines and more particularly to a machine for the automatic continuous performance of a sealing material emplacing and tamping operation in the assembly of spark plug components.

A spark plug basically consists in a pair of electrodes which terminate in spaced electrode points and which are held in position and insulated from each other by an insulator that also forms the main body of the plug. One of the electrodes usually is centrally located and the other usually is mounted on a shell which is located exteriorly of the body and by which the plug is mounted in the engine. The insulator usually is fabricated from a highly specialized ceramic material having the necessary physical properties and the electrodes and their connecting elements are assembled relative to each other by being rigidly positioned relative to the ceramic body.

The central electrode of a spark plug may extend nearly to the top of the ceramic insulator body and is electrically connected to an upper terminal stud which, in turn, makes an electrical connection with the ignition distributing system. The electrode is emplaced in the insulator after the insulator has been fabricated and is held in place, in the best practice, by a sealing and insulating material which fills the spaces between the electrode and the body, serving to securely hold the electrode in place, to form a gas tight seal between the insulator body and the electrode and to insulate the electrode.

Some electrodes extend substantially through the insulator body, forming an annular space with the body. The sealing material fills such space. Other electrodes merely extend downwardly out of the body and, in this case, the sealing material may be compacted on top of the electrode with a conductor leading through the material, or the material itself may be electro-conducting or include electro-conducting substances. In almost all spark plugs, however, certain elements are present in substantially the same relationship. The plug has an elongated body and a central electrode projecting therefrom and some form of sealing material, for examples, powders, fibers, combinations of the two, etc., is compacted to hold the two in their proper relationship and stop gas leaks.

Similarly, the insulator body must be mounted in the surrounding shell to properly position these two parts relative to each other and to the central electrode and to prevent gas leaks around the insulator.

It is, therefore, the principal object of this invention to provide a machine for automatically charging sealing material in position to hold electrodes and spark plug insulator bodies in place relative to each other and for compacting such material at a selected pressure to insure both that a correct amount of material is used and that the material is correctly compacted.

More specifically, it is another object of this invention to provide a machine for automatically placing and compacting sealing material in the interior of an insulator body for holding and sealing the central electrode in place, which machine is provided with means for varying the amount of powder, the tamping pressure, and other considerations in accordance with the design and style of the spark plugs being assembled and in which the operations take place in a smooth continuous series rather than in intermittent step-by-step progression.

These and more specific objects and advantages will be apparent from the specification and drawings, in which:

Fig. 1 is a vertical sectional view of a machine embodying the invention, certain parts thereof being shown diagrammatically and certain parts being broken away.

Fig. 2 is a fragmentary, horizontal, sectional view taken substantially on the line 22 of Fig. 1.

Fig. 3 is a horizontal, sectional view taken substantially on the line 33 of Fig. 1.

Fig. 4 is a fragmentary, vertical view, partly in elevation and partly in section and on an enlarged scale, taken on the line 44 of Fig. 1.

Fig. 5 is a fragmentary, greatly enlarged vertical sectional view illustrating a spark plug body in position to receive and have tamped in place the central electrode holding and sealing powder.

Fig. 6 is a fragmentary, horizontal, sectional view taken substantially on the line 6-6 of Fig. 5.

Fig. 7 is a fragmentary, vertical, sectional view taken on the line 77 of Fig. 6.

The embodiment of the invention to be described is designed for the continuous automatic assembly of central electrodes and insulator bodies in which the electrode extends substantially through the body, leaving an annular space into which a powdery sealing material is charged and compacted. Similar mechanism, embodying many of the features may also be provided for assembling insulator bodies and outer shells and for charging and compacting similar material therebetween for sealing the two to hold them in position and prevent gas leaks.

A machine embodying the invention may comprise, among other parts, a general frame 10 by which the machine is supported on a floor or table. The frame 10 mounts a pair of brackets 11 on which is located a driving motor 12. The motor 12, through the medium of a chain 13, drives a sprocket 14 which is keyed or otherwise secured on one end of a horizontally extending worm shaft 15 that is journalled in a pair of coaxial bosses 16 formed in the main frame 10. A worm 17 is keyed on the shaft 15 and is engaged with a worm gear 18 keyed or locked on the lower end of a vertically extending tubular shaft 19 which is journalled by spaced bearings 20 in a cylindrical section 21 of the frame it).

A drum shaped body 22 having a generally cylindrical side wall 23 and a generally horizontally extending bottom 24 is disposed near the upper end of the tubular shaft 19. The body 22 has a hub 25 which is bolted to a flange 26 on the shaft 19 and which rests on the center race of the upper bearing 20. The body 22 thus rotates with the tubular shaft 19 and mounts a plurality of filling and tamping stations 27 (a complete station being illustrated in cross section in Fig. 4).

Before proceeding further with a description of the machine embodying the invention and, in particular, with a description of the upper section of a spark plug filling and tamping station 27, it is believed a description of a spark plug body 40 and its center electrode 69 (see Fig. 5) is required. In general, regardless of the particular style or size of a spark plug, it comprises the sintered ceramic body 40 which has a vertically extending center bore 6i, an outer shoulder 62, a conical lower nose portion 63 and an upper shaped portion 64. The bore 61 extends entirely through the body 46 and is preferably stepped intermediate its ends to form an internal shoulder 66.

The center electrode 60 is generally rod shaped and is provided with a disc-like flange 67 which rests on the shoulder 66. The lower portion of the electrode 68 protrudes through the lower end of the narrow portion 65 of the bore'61 and the upper end of the electrode 68 extends almost to the upper end of the portion 64 of the ceramic sintered body 40 where it receives a stud connection for the ignition system.

Each of the tamping stations 27 has an upper and lower cooperating section. The lower section of each of the tamping stations 27 consists in a hollow cylinder 28 (see also Fig. 4) which is mounted by a sleeve bearing 29 for vertical reciprocation in a bracket 3-9 supported in a vertical way 31 on the exterior of the cylindrical wall 23 of the drum shaped body 22. Bolts 32 are provided to lock the bracket 30 in place. Each of the hollow cylinders 28 contains a piston 33 which is vertically siidable within the cylinder 28 and has a washer 34 at its lower end to provide a fluid tight seal with the cylinder wall 28. A neck 35 of the piston 33 extends through a central opening in a cylinder cap 36 and a washer 37 provides a fluid seal around the neck 35. At the uppermost end of the neck 35 there is located a removable cap or holding fixture 38 having a generally cone-shaped vertical socket 39 (see also Fig. for the reception of a spark plug insulator 4d. The cap 38 is retained in place on the upper end of the neck by a set screw 41 and can easily be removed for the substitution of a different sized cap 38 which fits a different type or style of spark plug body.

At the lowermost end of the cylinder 28 a horizontally extending open slot 42 is provided for the reception of a rounded end 43 on a generally horizontally extending arm of one of a plurality of corresponding bell crank levers 44, each of which is pivotally mounted by an car 45 secured on the underside of the bottom 24 of the drum shaped body 22. The other arm of the bell crank lever 44 extends downwardly carrying on its lower end a roller 46 which rides on the edge of a horizontally extending profile cam 47 (see also Fig. 3) which is bolted to the exterior of the cylindrical section 21 of the frame and thus remains stationary while the bell crank levers rotate with the body 22.

The lower end of the cylinder 28 is provided with a bore 48 (see Fig. 4) which leads into its interior beneath the piston 33 and is connected by a flexible tube 49 to a fluid manifold 58 secured on the under side of the bottom 24 of the drum shaped body 22. The fluid manifold 50 is connected by piping 51 to a fluid pressure accumulator chamber 52 that is supported on the upper end of the vertically extending hollow shaft 19. The fluid pressure accumulator chamber 52 has a vertical bore 53 into which there extends a plunger 54, the upper end of which is provided with a center post 55 and collar 56 for the reception of a selected number of disc weights 57 A fluid pressure gauge 58 is connected to a portion of the pipe 51 that extends upwardly through a drum cover 59 and is in communication with the fluid pressure chamber 52 and through the piping 51, manifold 50 and tubing 49 with the interior of each of the vertically movable cylinders 28.

Irrespective, therefore, of the vertical movement of any of the cylinders 28 or the rotation of the drum shaped body 22, a controlled fluid pressure exists within the closed fluid pressure system delineated by the interior of the conduit and chambers just described and, depending upon the number of weights 57 placed on the collar 56 and acting through the plunger 54, a constant pressure is exerted resisting the downward movement of each and all of the pistons 33 in their respective cylinders 28.

As the drum shaped body 22 rotates the rollers 46 on the lower ends of the bell crank levers 44 ride on the periphery of the stationary cam 47 and are rocked about their pivots in the ears 45. This raises and lowers the cylinders 28 in their brackets 30 between the two extreme positions shown in Fig. l in which the leftside illustrates the lowermost position of the cylinder 28 corresponding to the lower surfaces of the cam 47 and the right side of the drawing illustrates the uppermost position of one of the cylinders 28 which occurs when its corresponding bell crank 44 is swung in a maximum direction counterclockwise by its roller 46 striking an upper portion of the cam 47.

It is to be understood that the number of spark plug impacting stations 27 which are mounted on the exterior of the drum 22 and their associate bell crank levers 44 and flexible tubings 49 is limited solely by physical con-' siderations, i. e., the number of such stations which can be mounted upon a drum of a size appropriate for the space in which it is to be housed and the desired number of spark plug parts to be assembled during each period of operation.

As can be seen in Fig. 3 the cam 47 has an elongated dwell surface 68 at one side and this locates the operators station. This elongated dwell 68 results in the cylinders 28 remaining at the lower limit of their movement while each of them passes this portion of the machine and this dwell permits an operator to remove a tamped plug and to place a body 40 containing a center electrode 60 in each of the holders 38 as it passes him. As the drum 22 rotates farther in a clockwise direction (Fig. 3) each of the rollers 46 rides up a rise on the cam.

around the center electrode 60 is mounted by means of a.

bracket 71 on each of the ways 31 above each of the reciprocable cylinders 28 and in line therewith and constitutes the upper section of a tamping station 27. This mechanism consists in parts for dumping a measured charge of powder, feeding the charge around the center electrode 60, tamping the charge in place, clearing the powder feeding needle and restoring the mechanism for a subsequent charge and temp. The mechanism includes a pair of vertically extending parallel slide rods 72 and 73 which are fixedly positioned in a web 74 of the bracket 71 being secured thereto by lock nuts 75. A vertically reciprocable slide 76 is mounted to slide up and down on the two slide rods 72 and 73 being urged downwardly V thereon by a pair of coiled springs 77 which surround the slide rods 72 and 73 and act between lower faces of the web 74 and a pair of washers 78 resting on the upper surface of the slide 76. The slide 76 consists in a lower plate 79 (see also Fig. 7) which is screwed to a slide block 80. The plate 79 is provided with a generally centrally located coned aperture 81 for the reception of the upper. end of the spark plug body 40 (as shown in Fig. 5) to maintain the body coaxial with the aperture 81. Downward movement of the slide 76 is limited by a pair of washers 82 secured by nuts 83 threaded on the lower ends of slide rods 72 and 73 and limits the travel of the slide as illustrated in Fig. 4.

An oscillating feeder plate 84 is mounted to oscillate on the slide rod 72 in a bore 85 in the slide block 80. The feeder plate 84 has a generally tubular shaped section surrounding the slide rod 72 and a flat extension 86 which has a vertical hole 87 near its end. A pin 88 extends through the cylindrical portion of the plate 84 and is engaged in a vertical cam slot 89 milled in the slide rod 72. As the slide 76 moves vertically from the In the position illustrated in solid lines in Fig. 6, the 7 hole 87 in the extension 86 of the feeder plate 84 is invertical alignment with the lower end of a feeder tube 90 (see Figs. 1 and 7) which extends through the bracket 71 and is threaded into the slide block 80. A receptacle 91 is located on the upper end of the tube 96 and contains a supply of the pulverulent material to be tamped around the center electrode 60.

Thus with each vertical reciprocation of the slide 76, the feeder plate 86 is rotated between its two positions, first being rotated in a clockwise direction (Fig. 6) to move a charge of powder contained in the hole 87 over to and above the cone shaped aperture 81 in the plate 79 and in line with the open upper end of the bore o1 in the spark plug body 49. This position of the mechanism with the feeder plate extension 86 in the plug charging position is illustrated in Fig. 7 where a plug body 41) is shown just after having been moved upwardly against the slide plate 79 and the charge of powder 71) is shown as loosely lying in the annular space surrounding the center electrode 69 in the bore 61. When the tamping has been completed the corresponding cylinder 23 is lowered, lowering the spark plug body 49 and allowing the spring to return the slide 76 to its lowermost position. During this movement the pin 88 in the cam slot 89 returns the feeder plate extension 86 to the position shown in the dotted lines in Fig. 6 to receive another charge of powder in its feeding hole 87.

The means for tamping a charge of powder in place around the center electrode consists in a hollow removable tamping tool 92 (see Figs. 4, 5 and 7) which is rigidly mounted in the lower end of a tube 93 that is, in turn, adjustably secured in a vertical bore 94 extending through the web 74 of the bracket 71 between and parallel to the two slide rods 72 and 73. The tool 92 to be employed in tamping and sealing and holding powders in a selected spark plug body 40 is of such size as to enter and substantially fill the annular space surrounding its central electrode 6G in its bore 61 and thus for each size and style of spark plug body 40 a difierent tamping tool must be employed. Simple demounting means consisting in a corresponding cone shaped socket and shoulder 94 on the tool and in the lower end of the tube 93 are provided for seating the tool therein and a transversely extending hole 95 is provided for receiving a knock out tool 96 (shown in broken lines in Fig. 5). The tube 93 can be vertically adjusted relative to the tube 74 and thus the position of the lower end of the tool 92 adjusted relative to the position of the particular spark plug body being operated on by means of a pair of lock nuts 97 which are engaged with the exterior of the tube 93 and locked above and below the web 74.

The tube 93 is hollow and contains a vertically reciprocable plunger 98 at the lower end of which there is fixed a cleaning tool in the form of a drill 99 which extends downwardly through the center of the tamping tool 92. A spring 100 surrounds an upper smaller diameter portion 101 of the plunger 98 and acts between the plunger 98 and a cap 102 closing the upper ends of the tube 93. The portion 101 extends through the cap 162 and has a knurled knob 103 aflixed thereto. As the spark plug body is moved upwardly approaching the position shown in Fig. 5, the lower end of the drill 99 engages with the upper end of the center electrode 6:) and the plunger 98 moves upwardly against its spring 100. This removes the cleaning drill 99 from the center bore of the tool 92 as the center electrode 60 replaces it therein during the time that tamping tool 92 is compacting the charge of powder around central electrode 69. At the completion of the tamping operation the station rotates and as the cylinder 28 is lowered lowering the spark plug body 40, the spring 100 correspondingly expands and the cleaning drill 99 follows the center electrode down within the bore of the tool 92. Thus the drill 99 ejects from the tool 92 any small amount of powder 70 which may have adhered thereto.

If desired, the cleaning action may be augmented by rotating the cleanin tool, and for this purpose a bracket 104 (Figs. 1 and 3) which has a friction surface 105 is mounted to engage each of the knurled knobs 103 on the uppermost ends of the plunger 98 at a selected position of movement of the machine. This engagement rotates knob 103 and the engaged plunger 98, turning the drill 99 and insuring that the interior of the corresponding tool 92 remains free of powder.

The tamping of each successive charge of powdered material at the selected tamping pressure is provided for by the fluid pressure maintained in the closed fluid system earlier described. The weights 57 are so selected as to provide the desired fluid pressure beneath each of the spark plug body carrying pistons 33 in their corresponding cylinders 28. Therefore, as each of the cylinders 28 is moved upwardly, causing the deposit of a powder charge into the annular space surrounding its central electrode 6t), insertion of the tamping tool 92 therein, and finally the tamping of the charge, the positive upward movement of the cylinder 28 occasioned by the rocking of the bell crank lever 44 thrusts the tamping tool 92 against the loose powder of the last charge made. When the powdered material has been compacted to the desired degree and to compensate for the reduced distance of movement of the tool 92 necessary to compact successive charges of powder, the mechanical upward movement of the cylinder 28 beyond the distance necessary so to compact the powder, is compensated for by a downward movement of the piston 33 in its cylinder, expelling fluid from the interior of the cylinder 28 into the closed fluid system and forcing the weights 57 on their plunger 54 upwardly to compensate therefor. Since the weight 57 remains constant during the entire cycle of operation, the same force is required to raise the weights 57 by transmission of force through the fluid system and thus each successive charge of powder, although less mechanical movement is required to accompany it, is tamped at the selected pressure determined by the number of weights 57 acting against the closed fluid system. The fluid system is preferably filled with a liquid, although gas under pressure may be used.

This upward and downward movement of the plunger 54 and its weights 57 may be used to provide for safety switching means to disconnect the motor 12 from its source of power in the event of a jam of one of the tools 92 against a central electrode 60 or plug body which would result in a compensatory downward movement of the corresponding piston 30 in excess of that normally to be expected. Conversely, if for some reason the tool 92 were to become broken or for other reasons should not press downwardly on the powder charge with the desired pressure, insuflicient fluid would be displaced from beneath the corresponding piston 33 and the plunger 54 and its weights 57 would not be raised but instead would drop slightly. Limit switches 106 (see Fig. 1) translate this excessive or insulficient movement into control for the motor 12.

By positioning the several adjustable means provided in both the upper and lower elements of each tamping station correctly and by the selection of appropriate tools 92 and the correct number of weights 57, a machine embodying the invention can easily and quickly be adjusted to tamp the holding and sealing powder around the central electrode of any one of a large number of varying styles, types and sizes of spark plugs.

The continuous even flowing operation of the machine as contrasted to an intermittent, station-to-station or step-by-step system of operation which might be employed, has an advantage in a machine of this type where parts are loosely assembled and should be retained in such loosely assembled position until the operations performed on the machine are finished. For example, if the machine operated intermittently or progressively from station-to-station, after the spark plug insulator body 40 and central electrode were placed in one of the socketsfi9 yland the machine then indexed from one station to the next, the abrupt starting or stopping of the I movementquite easily might displace the component parts relative to each other. This undesirable displacement of parts relative to each other probably would be even more objectionable in a modification of the machine designed for the assembly of insulator bodies and shells because in most spark plugs the insulator body is many times taller than the shell in which it is positioned and thus less stable when resting loosely therein. However, in the smooth continuous flowing movement around the machine, the component parts of the plug remain properly positioned relative to each other and the continuous rotation of the machine elements allows a very high speed of operation without introducing objectionable vibration. The absence of such vibration resulting from the intermittent starting and stopping of the machine has another advantage in that it eliminates shock loads and serious damage to elements of the machine which would cause higher maintenance costs and reduce the efiective operating time of the machine.

In the modification of the apparatus disclosed, the lower sections of the tamping stations 27 have been described as being vertically movable to carry the spark plug bodies upwardly against a stationary tamping tool 92. Under certain conditions as, for example, Where the construction of the insulator body and the central electrode or the body shell is such that the component parts will not remain in their proper relative positions without being held, or for other reasons, it might be desirable to move the upper section of the tamping stations downwardly against the plugs. In such a case the lower sections of the tamping stations would remain stationary and the upper sections of the tamping stations would be mounted on vertical reciprocable slides which could be driven up and down in the same manner as the lower sections are activated in the mechanism illustrated in the drawings.

In the description of the apparatus constituting the invention, the mechanism has been shown as arranged for the charging and compacting of powdery sealing material and, for simplicity, the spark plug bodies have been shown as extending upward.

Where fibrous sealing material is employed, the charging means may be modified to control the charges of material and the plug bodies may be held in a horizontal position to facilitate operations when desired.

If the central electrode does not extend into the core of the insulator body, as for example where it is shaped like a plug in the bottom of the body, the sealing material may be emplaced on top of the electrode .and, in

such cases, the tamping tool 92 would not be a hollow needle but, instead, might be a solid ram,- fitting the interior of the insulator body quite closely.

What we claim is:

l. A machine for assembling spark plug bodies and central electrodes having elongated upwardly open annular spaces therebetween that comprises, in combination, a rotary frame, a plurality of stations mounted on said frame, each of said stations having a lower section comprising, a vertically reciprocable mount, a support adapted to removably receive a loosely assembled spark plug body and central electrode, said support being vertically movable relative to said mount, and pressure applying means for holding said support in upper position on said mount and for resisting downward force on said plug and support with a selected pressure, mechanism for vertically reciprocating each of said mounts a predetermined distance and a number of reciprocations for each rotation of said frame, each of said stations also having an upper section comprising, a bracket, a downwardly directed, hollow tool adapted to enter the annular space between a spark plug body and a central electrode, said tool being adjustably mounted in said bracket, powder charging meanshaving an actuating element extending below said tool and engaged by the upper end of a spark plug body for depositing a measured charge of powder in such annular space prior to the entry of said tool therein, a tool cleaner normally extending downwardly into said tool and displaceable upwardly therefrom by said electrode as said tool enters such annular space, and means for applying a predetermined pressure to all of said individual station pressure applying means whereby each consecutive charge of powder is compacted in each annular space with the same pressure.

2. In a machine according to claim 1 the improvement in pressure applying means that consists in a closed fluid system having a cylinder and a pressure piston, means for applying selected weights to said piston, an individual closed cylinder in each of said mounts, a support piston in each of said individual'cylinders, said support piston mounting the corresponding one of the spark plug body supports, and manifolding connecting all of said cylinders in a common system whereby downward movement of each of said support pistons resulting from pressure of the tamping tool on the powder being compacted is resisted by said. weights acting through said system and when the pressure determined thereby is reached no further compaction of the powder takes place.

3. In a machine according to claim 1, mechanism for vertically reciprocating the mounts that consists in a stationary cam having a selected number of rises and a longer low section, and a cam follower for each of said stations linked to the corresponding one of the mounts whereby each mount is raised a predetermined distance, for each rise on said cam and remains in lowered position for a section of the rotation of the frame during which an assembled plug body can be removed from the body support and a plug body and electrode to be assembled can be placed on the body support.

4. In a device according to claim 1, a tool cleaner comprising a drill-like pin extending downwardly into and substantially filling the tool, a shank extending upwardly from said pin, a spring acting to hold said pin down and compressed when said pin is moved upwardly, and means for rotating said pin periodically when extended entirely into said tool for removing powder from said tool.

5. A machine for inserting and compacting a measured quantity of sealing powder ata selected pressure in the elongated annular space between a spark plug body having a shouldered center bore and a central electrode of smaller diameter that has an annular flange adapted to lie against the shoulder in the bore of the spark plug body, said machine comprising, in combination, a base, a hori zontally rotatable drum-like frame mounted on said base, means for rotating said frame, a main hydraulic pressure chamber supported on said frame and having a piston, means for applying a selected pressure to said piston and creating a selected pressure in said chamber, a plurality of spark-plug assembly stations mounted on the outer periphery of said frame, each of said stations having a lower and upper section, each of said lower sections comprising, a vertically slidable mount having a cylindrical hydraulic chamber, a vertically movable piston in said chamber, and a spark plug body support on said piston, flexible tubing connecting said main hydraulic pressure chamber to each of said station hydraulic chambers in a common hydraulic system, means for vertically reciproeating each of said mounts a selected number of times during each rotation of said frame comprising a stationary cam mounted on said base and having a series of actuating surfaces, a follower for each of said lower sections mounted on said frame and engaged with said cam and said section, said cam having a non-actuating surface corresponding to an operators station, each of said station upper sections comprising a'vertically adjustable section frame, a downwardly extending hollow tamping tool removably mounted in said section frame and adapted to enter the annular space between a spark plug body and a central electrode when a body is moved upwardly relative thereto, a vertically reciprocable, downwardly urged 9 slide, engaged by the upper end of a spark plug body prior to entry of said tool into the annular space, and movable upwardly therewith, means actuated by each upward movement of said slide for depositing a measured charge of powder in such annular space, a rotatable fluted tool cleaning pin extending downwardly into and filling said hollow tool and resilient means urging said pin downwardly, said pin being displaceable upwardly by entry of References Cited in the file of this patent UNITED STATES PATENTS Dewar Mar. 2, 1937 Munger et al. July 13, 1948

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