US3778224A - Jig for firing of ceramic spark plug insulation - Google Patents

Jig for firing of ceramic spark plug insulation Download PDF

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Publication number
US3778224A
US3778224A US00231606A US3778224DA US3778224A US 3778224 A US3778224 A US 3778224A US 00231606 A US00231606 A US 00231606A US 3778224D A US3778224D A US 3778224DA US 3778224 A US3778224 A US 3778224A
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US
United States
Prior art keywords
jig
spark plug
firing
bottom wall
insulators
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 - Lifetime
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US00231606A
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English (en)
Inventor
J Duffner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
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Filing date
Publication date
Priority claimed from DE19712112507 external-priority patent/DE2112507C/de
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
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Publication of US3778224A publication Critical patent/US3778224A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D5/00—Supports, screens or the like for the charge within the furnace
    • F27D5/005—Supports specially adapted for holding elongated articles in an upright position, e.g. sparking plugs

Definitions

  • the present invention relates to a jig for firing ceramic spark plug insulators, and more particularly to a novel jig for firing of such insulators in a high temperature oven.
  • Spark plug insulators are conventionally made of a suitable ceramic material, or a mixture of such materials, and are shaped to the desired configuration. However, when they are so shaped from such material, the insulators are soft and can be given the necessary high mechanical strength and electrical insulation characteristics only by being fired in -a firing oven, usually at temperatures of between substantially 1,500 and 1,650C.
  • these blanks that is the spark plug insulators which have been formed from ceramic material but have not yet been fired, are to be introduced into the firing oven, they are conventionally inserted into a jig provided for this purpose, usually called a burner capsule.
  • jigs are as a rule configurated as containers of rectangular or quadratic outline and are themselves bodies consisting of fire-proof ceramic ma-' terial.
  • the jigs must of course have sufficient mechanical strength, in order to be capable of supporting and retaining the ceramic spark plug insulators even at the highest firing temperatures which are to be encountered. To assure this it was heretofore thought that particularly the bottom wall of the jig must be very thick. This, of course, results in a significant reduction of the useable proportion of the interior space of the firing oven, especially in view of the fact that it is conventional to stack six of these jigs above one another so that in height six times the thickness of the bottom wall of the respective jig is lost as useable space.
  • a concomitant object of the invention is to provide such an improved jig of the type here under discussion, in which the difficulty and time consumed in handling the jig and the insulators are substantially reduced.
  • Still a further object of the invention is to provide such an improved jig in which it is possible to insert the spark plug insulators into the jig mechanically and automatically, rather than manually.
  • Still another object of the invention is to provide such a jig which reliably prevents damage of the inserted spark plug insulators.
  • a jig for firing of stepped-diameter ceramic insulators in a high-temperature oven which jig briefly stated comprises a body of fireproof material, said body having a bottom wall having two opposite major surfaces one of which faces upwardly and the other of which faces downwardly when the jig is in use.
  • the bottom wall is provided with a plurality of apertures each adapted to receive and retain a spark plug insulator.
  • Each of these apertures has a wider portion extending from the one towards the other surface and a narrower portion extending from the wider portion to the other surface.
  • the wider and narrower portions are adapted to respectively receive a large-diameter and a small-diameter section of a stepped-diameter spark plug insulator.
  • the novel jig is not provided with four side walls as in the prior art, but instead with at most two side walls on which additional jigs may be stacked.
  • FIG. 1 is a partially sectioned perspective view illustrating a jig according to the prior art
  • FIG. 2 is a view similar to FIG. 1., but illustrating a jig according to the present invention
  • FIG. 3 is a sectional elevation showing the novel jig with spark plug insulators inserted and illustrating means for ejecting the spark plug insulators after firing.
  • this jig is in the form of an essentially cup-shaped element of quadratic or rectangular configuration.
  • This prior-art jig has four side walls and a bottom wall 11, and is usually of ceramic material.
  • one of the side walls is not visible but it will be understood that the jig does have four of the side walls 10.
  • the thickness of the bottom wall 11 is conventionally between 20 and 25 mm.
  • These jigs are filled with spark plug insulators, or more particularly with soft blanks for such insulators, which are to be fired in order to be hardened.
  • These insulators of which one is illustrated, are of stepped diameter, having a wider section 13 and a narrower section 12. They are so inserted into the jig that they stand therein in upright condition and that adjacent ones of the insulators contact one another with their wider section 13.
  • ceramic inserts or wedges not illustrated
  • FIGS. 2 and 3 shows a jig according to the present invention which avoids the disadvantages of the prior art.
  • the jig in FIGS. 2 and 3 is also of ceramic material, particularly a ceramic material on the basis of alumina/mullite, the porosity of which is between 20 and 30 percent, having a bottom wall 14 which is provided with a plurality of apertures each having a portion 15 which is wider and which extends downwardly from the normally upper surface of the bottom wall 14, a portion 17 which extends from the region of the portion 15 towards the normally lower surface of the bottom wall 14 and which is narrower than the portion 15 and an intermediate portion 16.
  • the portions 15 and 17 are concentric with one another, and the portions 15 are, of course, adapted to accommodate the sections 12 (see FIG. 1) of the insulator blanks.
  • the spacing between the centers of these apertures, for instance of the sections 15, is so selected that it is only slightly greater than the diameter of the insulator sections 13, in order to assure maximum utilization of the surface area of the bottom wall 14. This means that prior to firing, the sections 13 of the various insulator blanks will either contact one another, that is the sections 13 of adjacent blanks will contact one another, or there will be very small play between the blanks when an insulator blank is inserted into each of the apertures of the jig.
  • the jig according to the present invention is filled with insulator blanks, not manually, but automatically, for which purpose the jig is placed onto a suitable conveyor which moves along and beneath a device which sequentially inserts blanks into the variousapertures of the jig.
  • This arrangement for moving the jig and inserting the blanks is not a part of the present invention, except that it is pointed out that the utilization of such a device is possible for the first time due to the particular configuration of the novel jig.
  • the novel jig will undergo dimensional changes during repeated firing, as does the jig known from the prior art.
  • the spacing between the apertures in the jig will also change over a period of time and the differences between the always identical spacing between adjacent inserting stations of the automatic inserting device and the changes in the dimensions between the adjacent apertures in the jig will be cumulative over a period of time so that when dimensional changes in the jig have occurred, in subsequent filling operations the apertures of the jig will no longer be properly aligned with the filling stations of the automatic filling device during the entire sequence of filling operations.
  • the aperture portions 17 are provided only in order to permit the insertion of the aforementioned pin. Rather, they have other purposes also. For instance, during the firing process the blanks 18 (illustrated in FIG. 3) will contract in their diameter and length by approximately 20 percent, so that they have rather large play in the apertures. In order to assure that no damage occurs to the converted blanks, that is to the fired insulators, which still are susceptible to such damage even after firing, pins 19 shown in FIG. 3 are inserted after firing from below into the aperture portions 17, lifting the fired insulators upwardly until they can be gripped by suitable gripping devices at the junction between their sections 12 and 13, and can be removed automatically to be deposited on repositories provided for this purpose.
  • novel jig thus permits not only the automatic loading but also the automatic unloading of the jig, thus increasing substantially the speed of loading and unloading and decreasing substantially the expenses involved in these operations.
  • the novel jig according to the present invention need have a bottom wall 14 which has a thickness of only about 7 mm. as opposed to the 22 mm of the prior art. This means that for each jig a thickness of 15 mm. is saved and when six jigs are stacked above one another in the firing cham ber of a high-temperature oven, a total of mm. can be saved.
  • This dimension corresponds approximately to the height of one of the jigs so that it is now possible to stack seven jigs in the space which previously was required 'for only six jigs, without having to change the dimensions of the oven chamber. This means an increase of 16.7 percent in the number of spark plug insulators which can be fired at one time.
  • the jig according to the present invention need have only two side walls 20 (see FIG. 2) instead of four side walls as in the priorart construction shown in FIG. 1, a further increase in the ability of the jig to hold spark plug insulators is achieved, amounting to 7 percent because the space previously required for the two omitted side walls can now be used for apertures in which spark plug insulators can be accommodated.
  • the support of upper jigs, that is those stacked on a lower jig, is provided by the two side walls 20, or rather by their upper edges.
  • a jig for firing of ceramic spark plug insulators in a high-temperature oven comprising a body of fireproof material, said body including a bottom wall having two opposite major surfaces one of which faces upwardly and the other of which faces down-wardly when said jig is in use; and a plurality of apertures provided in said bottom wall, each of said apertures having a wider portion extending from said one towards said other surface, and a narrower portion extending from said wider portion to said other surface so that a shoulder is defined at the juncture of the respective wider and narrower portions, each of said wider portions being adapted to receive a section of a spark plug insulator and to retain the latter resting upon the respective shoulder.
  • a jig as defined in claim 1 said body further having only two side walls extending upwardly beyond said one surface and adapted to support a similar jig on their respective upper edges.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Spark Plugs (AREA)
  • Furnace Charging Or Discharging (AREA)
US00231606A 1971-03-16 1972-03-03 Jig for firing of ceramic spark plug insulation Expired - Lifetime US3778224A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19712112507 DE2112507C (de) 1971-03-16 Brennkapsel fur Zundkerzensteine

Publications (1)

Publication Number Publication Date
US3778224A true US3778224A (en) 1973-12-11

Family

ID=5801655

Family Applications (1)

Application Number Title Priority Date Filing Date
US00231606A Expired - Lifetime US3778224A (en) 1971-03-16 1972-03-03 Jig for firing of ceramic spark plug insulation

Country Status (5)

Country Link
US (1) US3778224A (enrdf_load_stackoverflow)
BR (1) BR7201105D0 (enrdf_load_stackoverflow)
FR (1) FR2129417A5 (enrdf_load_stackoverflow)
GB (1) GB1375489A (enrdf_load_stackoverflow)
IT (1) IT950068B (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3861867A (en) * 1973-08-29 1975-01-21 Kenneth R Ouhl Tray for oven-firing porcelain dental bridges and like dental appliances
US4174950A (en) * 1977-12-19 1979-11-20 United Technologies Corporation Ceramic base and cap useful in firing ceramic shell molds
US4348176A (en) * 1980-12-02 1982-09-07 Westinghouse Electric Corp. Material handling apparatus for insulators
US4354830A (en) * 1980-12-02 1982-10-19 Westinghouse Electric Corp. Ceramic greenware support
US5597397A (en) * 1994-04-15 1997-01-28 Flachglas Aktiengesellschaft Transfer device for bent glass sheets
US20170248367A1 (en) * 2016-02-26 2017-08-31 Mitsui High-Tec, Inc. Tray and heat treatment method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9124403D0 (en) * 1991-11-16 1992-01-08 Foseco Int Ceramic material

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1513617A (en) * 1924-02-11 1924-10-28 Litt Max Method of firing rack bars
DE889726C (de) * 1939-03-25 1953-09-14 Bosch Gmbh Robert Hilfskoerper zum Halten von Zuendkerzensteinformlingen beim Brennen
US3499634A (en) * 1968-02-14 1970-03-10 Champion Spark Plug Co Combustible support

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1513617A (en) * 1924-02-11 1924-10-28 Litt Max Method of firing rack bars
DE889726C (de) * 1939-03-25 1953-09-14 Bosch Gmbh Robert Hilfskoerper zum Halten von Zuendkerzensteinformlingen beim Brennen
US3499634A (en) * 1968-02-14 1970-03-10 Champion Spark Plug Co Combustible support

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3861867A (en) * 1973-08-29 1975-01-21 Kenneth R Ouhl Tray for oven-firing porcelain dental bridges and like dental appliances
US4174950A (en) * 1977-12-19 1979-11-20 United Technologies Corporation Ceramic base and cap useful in firing ceramic shell molds
US4348176A (en) * 1980-12-02 1982-09-07 Westinghouse Electric Corp. Material handling apparatus for insulators
US4354830A (en) * 1980-12-02 1982-10-19 Westinghouse Electric Corp. Ceramic greenware support
US5597397A (en) * 1994-04-15 1997-01-28 Flachglas Aktiengesellschaft Transfer device for bent glass sheets
US20170248367A1 (en) * 2016-02-26 2017-08-31 Mitsui High-Tec, Inc. Tray and heat treatment method
US10365042B2 (en) * 2016-02-26 2019-07-30 Mitsui High-Tec, Inc. Tray and heat treatment method

Also Published As

Publication number Publication date
FR2129417A5 (enrdf_load_stackoverflow) 1972-10-27
DE2112507A1 (enrdf_load_stackoverflow) 1972-09-14
IT950068B (it) 1973-06-20
DE2112507B2 (de) 1972-09-14
BR7201105D0 (pt) 1973-05-03
GB1375489A (enrdf_load_stackoverflow) 1974-11-27

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