US3783489A - Apparatus for firing ceramic sparkplug insulators - Google Patents

Apparatus for firing ceramic sparkplug insulators Download PDF

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Publication number
US3783489A
US3783489A US00279634A US3783489DA US3783489A US 3783489 A US3783489 A US 3783489A US 00279634 A US00279634 A US 00279634A US 3783489D A US3783489D A US 3783489DA US 3783489 A US3783489 A US 3783489A
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US
United States
Prior art keywords
insulator
pin
jig
aperture
sleeve
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
Application number
US00279634A
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English (en)
Inventor
J Duffner
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Robert Bosch GmbH
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Robert Bosch GmbH
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Publication date
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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
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/53—Means to assemble or disassemble
    • Y10T29/53978—Means to assemble or disassemble including means to relatively position plural work parts

Definitions

  • the present invention relates to an apparatus for firing ceramic sparkplug insulators, comprising a jig and apparatus for automatically loading and unloading the same.
  • Sparkplug insulators are conventionally made of a suitable ceramic material, or a combination 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 1,650 C.
  • a firing oven usually at temperatures of between substantially 1,500 and 1,650 C.
  • these blanks that is the sparkplug 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 quadrangular outline and are themselves bodies consisting of fire-proof ceramic material.
  • the jigs must of course have sufficient mechanical strength, in order to be capable of supporting and retaining the ceramic sparkplug 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 usable proportion of the interior space of the firing oven, especially in view of the fact that it is conventional to stack six of the jigs above oneanother so that in height six times the thickness of the bottom wall of the respective jig is lost as unusable space.
  • Still another object of the present invention is to provide such an improved jig which makes it possible to insert the sparkplug insulatorsinto the jig mechanically and automatically, rather than manually.
  • a concomitant object of the present invention is to providesuch an improved jig whose bottom is provided with a plurality of apertures each permitting insertion of an inserting apparatus into the jig so as to engage a respective sparkplug insulator and locate the same in the aperture so that a portion thereof is accommodated in the aperture in the bottom wall.
  • a further object of the present invention is to provide a jig which reliably prevents damage of the inserted sparkplug insulators.
  • a still further object of the present invention is to provide an apparatus, which is simple in construction, for automatically inserting the insulators into the jig.
  • An additional object of the present invention is to provide such an apparatus for inserting the sparkplug insulators into the apertures of the bottom wall of the jig which reliably centers the sparkplug insulators in respect to the respective apertures during their insertion.
  • an apparatus for firing stepped-diameter ceramic sparkplug insulators each having a larger diameter section and a smaller diameter section comprises a jig having an apertured bottom wall.
  • Each aperture is adapted to receive and retain the smaller diameter section of a respective insulator and to prevent the larger diameter section of said respective insulator from entering therein so that the latter may rest on said bottom wall while partially in serted into an aperture.
  • Engaging :means are provided for acquiring and centering the insulators during automatic loading of said jig.
  • each aperture in the region where an insulator is to rest on the bottom wall of said jig has a diameter greater than that of the smaller diameter section of the insulator prior to firing, and smaller than that of the larger diameter section of the insulator subsequent to firing.
  • said bottom wall is normally arranged horizontally while loading of the jig with insulators is carried out by lowering the latter into the jig from above.
  • Said engaging means comprises pin means having a free end dimensioned to matingly engage the central bores of the insulators.
  • Said pin means is arranged to move vertically along the axis of an aperture being filled between a first position wherein said free end is below said bottom wall, and a second position in which said free end has penetrated a respective aperture and projects upwardly above said bottom wall.
  • Clamping means cooperative with said pin means and said apertures to maintain said pin means coaxially aligned with the axes of the respective apertures in which said pin means is positioned.
  • FIG. 1 is a partially sectioned perspective view illustrating a jig according to the present invention, with two sparkplug insulators inserted therein;
  • FIG. 2 is a sectional elevation of the jig shown in FIG. 1 with sparkplug insulators inserted therein, and further illustrating means for inserting the sparkplug insulators into the jig prior to firing; 7
  • FIG. 3 is a sectional elevation of the jig illustrated in FIG. 1 with sparkplug insulators inserted therein, and further illustrating means for removing the sparkplug insulators subsequent to firing;
  • FIGS. 4 and 5 are sectional elevational views showing two further embodiments of the jig of FIG. 1.
  • the jig in accordance with the present invention is in the form of an essentially cup-shaped element of quadratic or rectrangular configuration.
  • the bottom wall 10 may have a thickness of.approximately 35 millimeters and is provided with a plurality of apertures 11 which, in the normally horizontal position of the bottom wall 10, have their axes extend substantially vertically.
  • the sparkplug insulators 25 which are to be fired, each essentially comprise a larger diameter section 12 and a smaller diameter section 13 the diameter of the smaller section 13 being somewhat smaller than that of the apertures 11 so that the sections may be fitted therein with some clearance.
  • the insulators 25 rest on the top surface 10a, as seen in FIG. 1, of the bottom wall 10' since the diameters of the larger sections 12 are greater than the diameters of the apertures 11 which latter are bounded by upper rims 11a.
  • the diameter of the apertures 11 should be selected so that it is larger than that of the smaller sections 13 prior to firing and smaller than that of the larger sections 12 subsequent to firing.
  • Two side walls 14 of the jig 10 project from the bottom wall 10' as shown.
  • the distances between the centers of adjacent ones of the apertures 11 are so selected that they are only slightly greater than the diameter of the insulator sections 12, in order to assure maximum utilization of the surface area of the bottom wall 10. This means that prior to filing the sections 12 of the various adjacent insulator blanks will either contact one another, or that there will be very small play between them when an insulator blank is inserted into each of the apertures of the jig.
  • the jig according to the present invention is advantageously loaded with insulator blanks not manually, but automatically.
  • the jig is placed onto a suitable conveyor which moves past a device which sequentially inserts blanks into the various apertures of the jig.
  • This device is illustrated in FIG. 2 and comprises a guide pin 15, whose free end 16 is so dimensioned that it can matingly engage a central bore 17 of a plug insulator 25.
  • the guide pin 15 is provided with a plurality of stepped sections, such as stop means 16a which is in the form of an enlarged diameter collar and serves for supporting the sparkplug insulator 25 and for preventing the free end 16 from penetrating into the bore 17 to an excessive depth.
  • an axially slidable expandable sleeve 18 which has outer and inner cylindrical surfaces.
  • the sleeve 18 has a stop portion 18', at the inner cylindrical surface of which there is provided a tapered portion 18a which defines therein a space whose cross section gradually decreases in the upward direction.
  • a bearing means Positioned inside the sleeve 18 is a bearing means in the form of an annular tapered bushing 19.
  • the bushing 19 is normally positioned near the region of the top portion 18 to cooperate with the portion 18a, as will hereafter be described.
  • the pin 15 is also provided with a stepped portion 15 which serves as a support for a spring 20 which acts upon the bushing 19 and urges the same in an upward direction relative to the position of the guide pin 15.
  • the arrow 19' illustrates the direction of the force applied by the spring 20 upon the bushing 19.
  • the sleeve 18, as suggested above, is expandable.
  • the sleeve 18 is preferably expandable in radial direction in the region of the top portion 18'.
  • the sleeve 18 may consist of two somewhat flexible semicylindrical shell sections.
  • Another possibility is a sleeve which is longitudinally slotted at least in the region of the top portion 18.
  • the normally unstressed sleeve 18 has an effective diameter which is slightly smaller than that of the apertures 11, so as to leave some clearance and facilitate insertion of the sleeve into a respective aperture.
  • the top portion 18' expands as described above, and the effective diameter of the upper portion 18' becomes equal to that of the respective aperture 11 to thereby result in engagement of the outer surface of the top portion 18' with the inner surface of the aperture 11.
  • the sleeve 18 may be thought of as a tong vise which holds the guide pin 15 aligned with the axis of the sleeve 18 prior to engagement of an insulator blank with the aperture, and which maintains the pin 15 aligned with both the sleeve 18 and the aperture 11 until insertion of the blank 25 into the aperture 11 has been effected.
  • the pin 15 is arranged for movement in an upward and downward direction, as illustrated by the arrow 15a; by means of a spring 21 a shoulder 22 of the pin 15 acts 'on a flange 23 of the sleeve 18.
  • the flange 23 is provided with a bearing surface 23.
  • the spring 21 urges the sleeve 18 in an upward direction, as viewed in FIG. 2, the movement of the sleeve 18 being limited by a stop 24 which is arranged to engage the bearing surface 23.
  • the jig is placed on a carrier and brought to a position below a supplying or feeding apparatus which is located above the jig.
  • the pin 15 initially in its lowered position, is aligned with one of the apertures 11 and is moved upwardly so that its free end 16 penetrates through the bottom wall 10' and extends towards the supplying apparatus. As the pin 15 moves upwardly,
  • the sleeve 18 similarly moves upwardly by the action of the spring 21.
  • the relative axial positions of the pin 15 and the sleeve 18 are such that the bushing 19 does not yet engage the tapered portion 18a and therefore the effective diameter of the top portion 18 is less than that of the aperture 11.
  • the initially smaller diameter of the sleeve 18 relative to the aperture 11 facilitates the insertion of the sleeve 18 into the latter.
  • the feeding apparatus releases the sparkplug insulator 25 so that the latter is brought to rest on the stop means or collar [60 as shown in FIG. 2.
  • the pin 15 begins to move downwardly.
  • the bushing 19 remains engaged with the tapered portion 18a so that the pin 15 remains coaxially aligned with the axis of the aperture 11 until when the top portion 18' is only partially inserted into the aperture 11 at least a portion of the smaller diameter section 13 of the insulator 25 is inserted into the aperture 11.
  • the lower portion of the guide pin 15 can be connected to a pneumatic, hydraulic or mechanical apparatus not shown)'which moves the guide pin 15 up wardly and downwardly in a programmed fashion so that the above process may be repeated successively with a plurality of apertures 11.
  • the driving mechanism for moving the pin 15 is not a part of the present invention except that it is point out that utilization of such a device is possible in order to fully automate the loading procedure as contemplated by the present invention.
  • the feeding apparatus referred to above is not shown an automatic gripping device of the type contemplated for use with the present invention being fully known and not forming part of the present invention.
  • the sparkplug insulator By utilizing the present invention, it is possible for the sparkplug insulator to be precisely centered prior to insertion into the apertures of the jig.
  • the above described apparatus is advantageously used either singly as shown in FIG. 2 to fill one aperture at a time or a plurality of such apparatus may be utilized in rows for successively filling rows of apertures until the entire jig is loaded.
  • a particular advan- V tage of the present invention in connection with the apparatus above described consists in that the loading of a jig utilized in firing such insulators becomes less dependent on the precise diameters of the holes in the insulators.
  • the utilization of such a jig no longer depends on the diameter of the holes as critically as in the prior art and is simiiarly not so critically dependent on the changes in the diameters of the holes of the jig materials and therewith also on the distances between the apertures the sparkplug insulators necessarily being centered in each instance by the abovedescribed device.
  • the novel jig will undergo dimensional changes during repeated firing, as do the jigs known from the prior art.
  • the spacing between the apertures and 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 adjacentapertures in the jig will be cumulative over a period of time so that, when dimensional changes in the jig have occured, 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 apertures l 1 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 every plug 25 will contract in its diameter and length by approximately 20 percent, so that it has a rather large play in the apertures.
  • pins 30 as illustrated in FIG. 3 are inserted from below into the respective apertures l 1 after firing, lifting the fired insulators upwardly until they can be gripped by suitable gripping devices (not shown) at the junction between their large and smaller sections 12 and 13, and can be removed automatically to be deposited on repositories provided for this purpose.
  • novel apparatus thus permits not only the automatic loading but also the automatic unloading of the jig, thereby increasing substantially the speed of loading and unloading and decreasing substantially the expenses involved in these operations.
  • the provision of the apertures in the bottom wall 14 of the novel jig increases the capacity of the jig for handling the insulators.
  • the conventional jigs in which the bottom wall is not apertured and the insulators rest on the top surface of the bottom wall, are known to have bottom wall thicknesses of approximately 22 millimeters. This corresponds to a loss of space in the firing oven of approximately the same dimension per jig, i.e., the overall height of the loaded jig is the sum of the thickness of the bottom wall and of the length of the insulators which rest in upright position on the upper surface of the same.
  • the insulators are over a significant part of their length accommodated in the apertures of the bottom wall so that the lost space above the upper surface of the bottom wall need only be e.g., 6mm, the distance by which the insulators project upwardly of the upper surface.
  • This represents a saving of 226 l 6 millimeters in the oven space per firing jig. lf six of these jigs are stacked above one another in the firing chamber of an oven, a total of 96 millimeters 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 sparkplug insulators which can be fired at one time.
  • the jig according to the present invention need have only two side walls 14 instead of four side walls required in the prior art'construction (where the insulators were not retained in apertures of the bottom wall), a further increase in the ability, of the jig to hold sparkplug insulators is achieved, amounting to approximately 7 percent because the space previously required for the two now omitted side walls can be used for apertures in which sparkplug insulators can be accommodated.
  • FIGS. 4 and 5 show the jigs 10 having apertures 11' and 11'', respectively, which are tapered in a sense first increasing downwardly and then increasing upwardly in their respective diameters.
  • Apparatus for firing stepped-diameter ceramic spark plug insulators each having a larger diameter section and a smaller diameter section comprising a jig having a bottom wall provided with a plurality of apertures each adapted to receive and retain the smaller diameter section of a respective insulator to prevent the larger diameter section of said respective insulator from entering therein so that the insulator may rest on said bottom wall while partially inserted into the respective aperture; and engaging means for acquiring and centering a respective insulator during automatic loading of said jig.
  • each insulator having a central bore, and said bottom wall being normally arranged horizontally while loading said jig with insulators is effected by lowering the latter into the apertures of the jig from above; and wherein said engaging means comprises pin means having a free end dimensioned to matingly enter into the central bores of the insulators, said pin means being arranged to move vertically along the axis of an aperture being filled between a first position wherein said free end is below said bottom wall and a second position wherein said free end has penetrated a respective aperture and extends above said bottom wall; and clamping means cooperating with said pin means and the respective aperture for maintaining said pin means coaxially aligned with the axis of the respective aperture while said pin means are positioned therein.
  • clamping means comprises expandable sleeve means coaxial with said pin means and enclosing at least a portion of said pin means with freedom of axial movement along the latter, said stop means being operative to limit the movement of said sleeve means above said stop means in a sense enclosing said free end.
  • said sleeve means has inner and outer cylindrical surfaces and a top portion which is expandable in radial direction whereby said outer cylindrical surface only frictionally engages said apertures when said top portion is expanded, said inner surface of said top portion including a tapered section; and further comprising bearing means cooperating with said pin means and said tapered section for expanding said sleeve means in response to upward movement of said pin means relative to said sleeve means beyond a predetermined extent while the insulator is outside of a respective aperture, to thereby maintain coaxial alignment of said pin means at least until the insulator is inserted into said aperture.
  • bearing means comprises an annular tapered bushing coaxially mounted for slidable movement on said pin means; and further comprising biasing means cooperating with said pin means to urge said bushing against said tapered section to thereby expand said sleeve means.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Spark Plugs (AREA)
  • Furnace Charging Or Discharging (AREA)
US00279634A 1971-09-09 1972-08-10 Apparatus for firing ceramic sparkplug insulators Expired - Lifetime US3783489A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2145057A DE2145057C2 (de) 1971-09-09 1971-09-09 Einrichtung zum maschinellen Füllen von Zundkerzenstein Rohlingen in Brennkapseln und Brennkapsel fur die Einrichtung

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US3783489A true US3783489A (en) 1974-01-08

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US00279634A Expired - Lifetime US3783489A (en) 1971-09-09 1972-08-10 Apparatus for firing ceramic sparkplug insulators

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US (1) US3783489A (de)
JP (1) JPS4836526A (de)
BR (1) BR7206106D0 (de)
DE (1) DE2145057C2 (de)
FR (1) FR2149230A6 (de)
GB (1) GB1405759A (de)
IT (1) IT1012039B (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4384132A (en) * 1978-12-27 1983-05-17 Degussa Aktiengesellschaft Bis-(silylethyl)-oligosulphides and process for their production

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5822224B2 (ja) * 1975-03-07 1983-05-07 テルモ カブシキガイシヤ クレンメ
JPS52143495U (de) * 1976-04-17 1977-10-31
JPS542515A (en) * 1977-06-09 1979-01-10 Souji Ishikawa Flow regulator for liquid passing through liquid conduit
JPS5466697U (de) * 1977-10-21 1979-05-11
US4238108A (en) * 1978-05-12 1980-12-09 Abbott Laboratories Flow control device
JPS599642Y2 (ja) * 1978-08-31 1984-03-27 テルモ株式会社 クレンメ
JPS5858150U (ja) * 1981-10-15 1983-04-20 株式会社ミドリ十字 ロ−ルクランプ
JPH0316570A (ja) * 1989-06-14 1991-01-24 Nissho Corp ローラクランプ
GB9124403D0 (en) * 1991-11-16 1992-01-08 Foseco Int Ceramic material
DE4334130C2 (de) * 1993-10-07 1997-04-17 Hoechst Ceram Tec Ag Vorrichtung zum Befüllen von Brennkapseln mit grünen Keramikteilen

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3667103A (en) * 1970-07-21 1972-06-06 Us Army Apparatus for inserting terminals in an apertured plate

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3667103A (en) * 1970-07-21 1972-06-06 Us Army Apparatus for inserting terminals in an apertured plate

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4384132A (en) * 1978-12-27 1983-05-17 Degussa Aktiengesellschaft Bis-(silylethyl)-oligosulphides and process for their production

Also Published As

Publication number Publication date
DE2145057C2 (de) 1973-10-25
DE2145057B1 (de) 1973-03-08
BR7206106D0 (pt) 1973-09-27
FR2149230A6 (de) 1973-03-23
IT1012039B (it) 1977-03-10
JPS4836526A (de) 1973-05-30
DE2145057A1 (de) 1973-03-08
GB1405759A (en) 1975-09-10

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