US2003465A - Machine for assembling spark plugs - Google Patents

Description

June 4,1935. H RA EZ AN 2,003,465-

MACHINE FOR ASSEMBLING SPARK PLUGS Original Filed Jan. 4, 1930 2 Sheets-Sheet 1 H. RABEZZANA Original Filed Jan. 4, 1930 2 Sheets-Sheet 2 June 4 Patented June 4, 1935 I UNITED STATES PATENT OFFICE MACHINE FOR ASSEM'BLING SPARK PLUGS ware Original application January 4, 1930, Serial No.

418,572. Divided and this application September 25, 1933, Serial No. 690,838

Claims.

This invention relates to the manufacture of spark plugs such as are used in the ignition system of an internal combustion engine and more particularly to a machine for practicing the im- 5} proved method of assembling the center electrode in the insulator core, as described in my application Serial No. 418,572, now Patent No. 1,940,323 of which this application is a division.

According to customary practice the center electrode is held in the core by suitable cement which also seals the bore against leakage of gases from the engine combustion chamber. In my prior co-pending application there is claimed an improved method of assembly suitable for high speed production and one which will insure a tight seal. The method contemplates the use of a center electrode having an enlarged screw threaded head at its upper end for threaded engagement within an enlarged portion of the insulator bore, and it involves the insertion of the electrode wire in the bore with the head screwed partly into place and then the injection under pressure of sealing cement into the bore and around the electrode to fill the bore, and finally the movement of the electrode to its proper operative position by screwing home the head thereof, whereby the cement within the bore is compressed and packed between the electrode and insulator core to completely fill all voids and eliminate air pockets and the like which would otherwise lessen or destroy the effectiveness of the seal, reduce heat transference between the electrode and core and cause rapid deterioration of the sealing material and plug parts.

This divisional application has to do with the apparatus disclosed in the parent case, by which the improved method of assembly is performed. Such apparatus is illustrated in the accompanying drawings in which Figure 1 is a view partly in section showing a machine adapted for commercial production work; Figure 2 is an enlarged sectional view of the parts for clamping the core on the cement nozzle and for spinning the electrode wire, and Figure 3 is a sectional View of a device suitable for small quantity production.

Referring first to Figure 3, the insulator core indicated by I is secured in the usual metal shell 2, the lower end of which is screw threaded for engagement in the spark plug opening of the engine combustion chamber. The center bore 3 of the core has an enlarged screw threaded portion 4 at its upper end. The electrode is shown as consisting of a center wire 5 having an enlarged screw threaded head 6 at the upper end with an intermediateabutment collar 7, that portion of the head above the collar being intended for the attachment of the usual lead wire or cable of the ignition system. These parts are first assembled to the position illustrated in Figure 3. That is, the center wire 5 is introduced in the bore 3 of the core and head 6 is partially threaded into the opening 4. With the parts in this relation, the shell 2 is threaded into an opening or pocket H1 in a metal block or die II, which previously has been filled with a suitable cement preferably in a semi-fluid or plastic state. Upon downward movement of the spark plug assembly, as the shell is rotated and engaged with the threads of the opening Hi, the plastic sealing material is compressed in the die and caused to fiowupwardly into the bore 3 of the core and around the electrode wire into the space provided by the enlarged portion 4 tothereby completely fill the space in the bore unoccupied by the electrode. Observance of the cement oozing or seeping out around the screw threads at the upper end of the core gives an indication that the bore is completely filled. Rotation is then stopped and .the shell can either be left in this position for the time being. or completely removed from the die ll, while the head 6 is threaded down until the collar 1 abuts or contacts tightly with the top surface of the core. It will be, apparent that the final movement of the electrode tightly compresses or packs the cement in the bore and particularly in the enlarged portion thereof, to get rid of any air pockets that may have been formed and tightly fill the whole space, thereby assuring a tight seal. After the excess material clinging to the bottom of the plug has been washed away and the cement in the bore given time to dry out and harden, the plug will be ready for use.

The machine shown in Figure 1 has been designed for production purposes and in this case the electrode is preferably assembled in the core prior to the time the core is placed in its metallic shell. This machine consists of a reservoir or container l5 for the sealing material, carried by a work table I6 and having a drain plug I! in its bottom wall and a removable cover l8. Projecting downwardly from the center of the cover is a stem or shaft l9 having pivoted at its lower end a rock shaft 20. One end of the shaft 20 is connected by the link 2| extending through a stufling box 22 in the head or cover l8 with a lever 23 which in turn is connected through a link 24 with an actuating lever 25 which may be pivoted to the fioor through a bracket 26 for depression by manual effort exerted through the foot of the operator. A contracting spring 21 may be provided to manually hold the lever 25 in retracted position. The opposite end of the rock lever 20 carries a stem projecting upwardly through the stand-pipe 3| secured to the cover l8 by the nut 32 and having at its upper end a valve head 33 that projects through a central opening of the guide plate or ring 34. In the drawings the valve is shown in open position, but it is normally held over the opening in the seat 35 secured in position by the nut 36, which also carries through fitting 31, the discharge nozzle 38 over which the lower end of the insulator core la is adapted to seat. Compressed air or other fluidunder pressure may be led to the top of the chamber l5 through a conduit 40 from a suitable source of supply to lift the sealing material in the standpipe 3| to the discharge nozzle when the valve 33 is opened.

Mounted above the pressure discharge mechanism is a reciprocatory device under manual control and including a carrier or frame having a pair of spaced apertured arms 43 and 44 slidably mounted on a post 45 and carrying an electric motor 46. This frame is movable downwardly by a hand lever 48 pivoted at an intermediate point to the frame and at one end connected by the shackle 49 with a collar 50 fixed to the rod 45 as by means of a set screw 5|. A coil spring 53 interposed between the fixed collar 59 and apertured arm 44 serves to yieldingly maintain the frame in its uppermost position. Extending downwardly through the dependent hub 55 ofthe motor housing is a spindle 56 carrying a chuck 51 in which is removably secured a spinner 58. Different sized spinners may be secured in the chuck in accordance with-the type of the spark plug to be assembled. This spinner is intended for frictional engagement with the collar la to rotate the same and screw the head of the electrode in the enlarged bore at the upper end of the core. The core is clamped over the discharge nozzle 38 by a collar 60 interchangeable with other collars to accommodate different sized:

plugs, in the aperture plate or disc 6|, which may be welded or otherwise secured to a slidable sleeve 62 keyed for telescopic engagementwith the sleeve 63, as by means of set screws 64 threaded in the sleeve 62 and projecting into elongated slots 65 in the sleeve 63. The upper end of the sleeve 63 is split so that it maybe contracted and held on the hub 55 as by means of a. clamp collar 61, an expansion spring 68 being placed over the discharge nozzle and the hand lever 48 is brought down to lower the clamping die 60 into engagement with the core for holding the core in place, the spinner 58 also being brought into engagement with the electrode collar 1a. If the electric motor is now actuated the electrode may be partially screwed into the bore, after which the foot pedal 25 may be depressed to allow the sealing material to enter and fill the bore until the operatorobserves leakage around the screw threads at the upper end when the valve is again closed and the motor actuated once more to spin the electrode into final position and thereby compress the sealing material introduced into the bore.

I claim:

1. Means to assemble an electrode in a spark plug insulator core, including means to move an electrode in the bore of the core, first to an intermediate part way home position and later to its proper operative position, and means to inject sealing material in the bore while the electrode is held in its first mentioned position for subsequent compression when the electrode is moved to its operative position.

2. Means to assemble an electrode in a spark plug insulator core, including means to forcibly inject a sealing material into the bore of the core and around a partly inserted and temporarily immovably positioned electrode, and means to move the electrode to fully inserted position subsequent to the filling of the bore to thereby compress said sealing material.

3. Means to assemble an electrode in a spark plug insulator core, including a reservoir for a supply of sealing cement under pressure, a valved device controlling the injection of sealing cement from said reservoir to the bore of the insulator, and means for moving the electrode partially into the bore prior to the injection of sealing cement and fully into the bore subsequent to the injection.

4. Means to assemble an electrode in a spark plug insulator core, including a reservoir for a supply of sealing cement under pressure, a discharge nozzle on which the core is adapted to seat, means to hold the core on its seat including a reciprocatory device having a spring pressed core engaging member at its end and a spinner device engageable with the electrode to move the same in the core.

5. Means to assemble an electrode in a spark plug insulator core, including a reservoir for a supply of sealing cement under pressure, a discharge nozzle on which the core is adapted to seat, means to hold the core on its seat including a reciprocatory device having at its end a pair of movable members, one being axially but nonrotatably movable relative thereto for engagement with the core and the other being rotatably but non-axially movable relative thereto for engagement with the electrode to sink the same in the core.

HECTOR RABEZZANA.

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