US1598201A - Process of and apparatus for making articles of ceramic material - Google Patents

Description

Aug. 31 1926. 1,598,201 c. G. KOPPITZ l v PROCESS OF AND APPARATUS FOR MAKING ARTICLES 0F CERAMIC MATERIAL Filed May 25, 1925 4 Sheets-Sheet 1 (Niv:

Aug. '31, 1926. 1,598,201

c. G. KoPPrrz PROCESS OF AND APPARATUS FOR MAKING ARTICLES OF CERAMIC MATERIAL Filed May 25. 1925 4 Sheets-Sheet 2- abbot nu 4 Sheets-Sheet 3 C. G. KOPPITZ Filed May 25, 1925 Aug. 31 1926.

PROCESS oF AND APPARATUS FCR MAKING ARTICLES oF CERAMIC MATERIAL Aug. 31 1926.

C. G. KOPPITZ PROCESS OF AND APPARATUS FOR MAKING ARTICLES OF CERAMIC MATERIAL Filed May 25. 1923 4 Sheets-Sheet 4 Patented Aug. 31, 1 926.'

UNITED 'STATES-PATENT oFF.;

CARI. G. xoPPITz, 0E GEEENSBUEG, PENNSYLVANIA, AssIeN INDUSTRIAL ENGINEERING COMPANY, foF GEEENSBUEG, PENNSYLVANIA, A Gon-iy PORATION 0F PENNSYLVANIA.

rEoCEss oF AND APPARATUS Eon MAKING. ARTICLES oF CERAMIC MATERIAL Application ned may 25, 1923. serial NoL 6411490.

This invention relates to process of and apparatus for making articles of ceramic material and more particularly to the manufacture'of high-voltage insulators. p

' Practically all high-voltage insulators as made at the present time consist of a number of units inA end to end relation, the number of units depending upon the voltageof the line to be insulated. In the case of pintype insulators a plurality of shells are cemented together with the usually grounded pin on the inside and the line and the wire on the .top and the outside. In the case of suspension insulators and' post--type insulators each of the separate units making up the complete insulator is provided with inside and outside hardware, the latter serving to secure the units in end to end relation as well as providing at one end a support for the insulator as a whole and affording at the other end an attachment of the current lcarrying conductor. l.

As isV well recognized by experts, standard insulators of the type referred to, particularly those lused on higher commercial voltages, say 44000 and above, have inherently certain drawbacks, the more important 'ones of which are as follows: v

l. They aremade up of many separate pieces of porcelain or other ceramic material.

2. In the case of suspension and'postftype vinsulators each separate unit requires two pieces of hardware.

3. The insulating `material is stressed electrically to a high limit between the pieces of hardware.

the porcelain failurefrequently occurs due to certain weathering and aging conditions, which means a short life and high replacement cost.

5. The distribution of 'electrical stress-be- 4tween the different units ofan insulator is veryruneven due to the inequality ofthe charging current' carried by theditferent units, which results in a highvoltagevdrop across the unit next to the conductor and ya comparatively low 'voltage drop across the unit neXt to the grounded support with f tages above pointed out. y4. Owing to the high electrical stress on v it, reference is made to the termediate units.

on To EAILWAS? ANn 6. In the case of electrical flash-mrof I theinsulators of the'suspension and posttype in service the kresultil'lg powerarc is very likely to be held iuclose contact with the porcelaindue to the action of the intermediate pieces of hardware, which often results in a shattering of the porcelain by ythe intense heat of the arc.

acter from end to endl..v is probably due to the fact that the cost of .manufacture of the latter by theold methods or processes was so hig as to inhibit the general use thereof. Y

`It is the general. object of the invention to provide a process of and apparatus for cheaply making articles- 'ofceramic material. i

making high voltage insulators.,`

Another specific object is the rovision of a process of and apparatus or cheaply manufacturing insulators of the high voltage type which have none of the disadvan- FoI'. al full understanding of the linvention the principle ofoperation` upon which it is based, and the advantages derived from drawings in which- Figs. 1-4 inclusive are cross-sections of different forms .of Insulators made accord` Ying to the lnvention;

. Eig." 5 vis a cross-sectional view of an It is a more particular object to provideJ accompanying apparatus generally adapted to carry out the object of the invention;

Fig. 6 is an end View of a part 'Figs 7, 8 and 9 are cross-sections taken on lines 747, 8-.8 andy respectively;

Fig-10 is a fragmentary cross-section of a 'modification of the arrangement shown in Fig. 5 for producing the type of insulatorsshown in` Figs. 1-4;

Fig. 11 is an end view thereof;

Fig. 12 is a view similar to Fig. 10 show# ing a different relative position of the parts;

and

Fig. 13 is aview similar toFig. 10 of another modification.

Fig. l shows a typicalv foijm of an/insulator as produced by the invention.

This form of insulator which has an overall lengthoff approximately inches and -is considered as safe for a line voltage of y held against the body `12 vunder pressure in order to. obtain greater bending strengthwhile the cement bond is applied and also .during the setting thereof.

The insulator shown in Fig. 2 has about the same length and voltage rating as that shown in Fig. 8 but is equipped with hardware 15 suitable for use as a 'ost-type insulator. -The tubularbody 16 as a gradually increasing thickness toward the bottom as such an insulator would require.

Fig. 3'shows a post-type insulator consisting of two parts 17 and 18 interconnected by meta1'flanges119 and 20 and carrying at the free ends metal caps 21 and 22 respectively for the usual purposes.

The wall of the part 18 is thicker than that of the part 17 in 0I- der to obtain the necessary bending strength with a minimum of material.

Fig. 4 shows an insulatordesigned tore- A' pla'cethe usual pin-type insulator in common use. The tubular body 24 carries at its lower end a flange 25 by which, it can be bolted to the cross-arm 2,6 of a mast and the top is shaped to provide a groove 27 for receiving the line wireand a peripheral groove 28 to receive the tie-wire 29.

In the foregoing reference has been made to several forms of insulators which while operatively equivalent to corresponding forms of insulators lnow in use, havenone of the disadvantages hereinbefore pointedwout. The forms disclosed in Figs. '1, 2 and 4 have only a single piece of porcelain or like with in the past and at the present time, Ow-

ing. to its shape and also due to the low unit of electric ,stress on the porcelain the insulator will not be susceptible of failure caused by deterioration and may have a practically infinite length of life. As the entire length of theinsulator from end to end is of insulating material, the distortion of the field of electrostatic stress is very slight, which of course means a substantially uniform distribution of stress throughout its length. Since there `are no intermediate oints of hardware and therefore no bases or interinediate arcs a power arc that could be produced must necessarily extend between the hardware members at the opposite ends. Such an arc is inherent] 'forced outwardly from the cold surface o the orcelain to a greater extent than the individual arcs between points intermediate the ends, whereby the danger of rupture or shattering by heat is correspondingly reduced and the liability of breakdown decreased.' l i It is also apparent that the use of only two pieces of hardware `involves a corre-l spondingly low cost inasmuch as the labor oor of cementing incident to t e application of K such hardware is reduced to adefinite minimum.

In the following will now be described the process by which the cost of making the insulators proper is also reduced to a re1a' tively small amount as compared with the prior art referred to. The principle of operation on which the invention is based is broadly disclosed in F ig. 5, which represents a standard pug-mill comprising the tubes 30 and 31 containing the screw conveyors 32 and 33 centered by spiders 32 and 33, re-

spectively and well known mechanism for operating the conveyors. To the tube 31 is attached a tube or barrel 34 at the free. end of which /is secured a core 35 which is spaced from the walls of the barrels to define an annular passage. 35 by means of a vspider frame 36 in which the stem 37 of the core is rigidly secured. The barrel 34 is surrounded by a tubularl I preferably center thecorc 1 10 f moldv 38 having a sliding fit thereon. The

mold, whichever way it may be made, must be of'porous material or have in general a relatively large absor tive capacity. The mold is slipped over t e barrel 34 and so positioned that its outer end is flush with the end of the core, as, approximately indicated indotted lines as Fig.'1. In practice plastic clay is fed into the mill and forced by the screwjconveyors over the conical portion lof the core into intimate contact with the walls of the porous mold 38. The force ofthe contact and the friction of the sliding fit 'of the mold on the barrel are so correlated that the mold moves under the drivin force of the clay maintaining the materia under a definite pressure or density. The

y carried away in the form of a hollow cylinder. The degree of plasticity and the char. acter of the mold are suchthat. the cylmdricalvbody formed remain in the position V given to it by the core.

In this way it is possible to produce tubes of much thinner walls than by tle usual process `inasmuch as the thin wall is uniformly supported by the mold. The mold, which may be dry plaster,'rapidly' absorbsl the water from the clay thereby giving 1t more rigidity and atthe same time releasing the bond between the two, so that the tubes may be safely removed longitudlnally, leaving the mold intact for the next opera- .tion after the same has been properlydried.

lasticity as to provide .a substantially Form consistency ,and uniform, density,

' the surplus of water is squeezed 'out to a considerable extent as the material is forced Asidefrom the stiii'ening of'the material resulting from the expulsion ofthe water, the

- bond, the form is self-supporting.

` equipped with a plurality o The mold 49, however, is made `in twokd l Tubes such. as produced by the process limited demand, but y certain modification of the plaster mold as for instance shown in Figs. 10-13, it is possible to commercially roduce tlibes fpsheds or deep corrugations thereby Amaterially increasing the external surface distance orl the effective electrical distance between the`ends as is well understood. Porcelain tubes with such an external surface 'iind a very useful application las outdoor use. v

In Figs. l0 and 1l.the barrel 40 is at-G tached to the pug-mill as shown in Fig. 5. or more parts, as indicated in Fig. 11, which 46 to the' outside. The mold lis preferably i the density' of the insulators i especially yfor closedfat its free end and is provided mere- 1y with a -small-- aperture 47 through which the air may escape and also part of the material. I 1 The operationis as follows:

` The mold 49 is slipped over the barrel 'and moved to the position indicated in Fig. 10 .and held temporarily in this position and when the pug-mill is now setr in operation, the clay is forced into the spaces defined by the mold and the core and out through theopening 47. When all the air is driven out and the material thoroughly knitted inthe middle of the head the mold .is released and under the force of Contact .Jand impact the mold is moved -awayin the manner described in connection with Fig.

i 5. `As the feeding action continues, the an- .Y

material is uniform throughout. Naturally with uniform rate of feed of the clay, the movement of the mold is not uniform but 'stepwise due tothe through passage tube 45 ind passage 46. t

Cement lock sur-faces 48,'and 48a consisting of protrudingcorrugations or diambndshaped points areformed in the same manner as the sheds. The tube formed will extrude to the open end of the mold but is cut olf subsequently nextto the cement lock-I ing surface48.

The mold with the formed material in it is set aside for a short time allowingthe plaster to absorb a suiiicient amount of the water from the clay to strengthen it and to release the bond between the plaster and the clay. The two halves ofthe mold are then separated, the hardened plastic body removed and t e'plug 44'withdrawn.

lThe clay may now be left to dry thor=y oughly, fins at the parting lines of the split mold,

ythe material extending .from the head of the tube and the excess tube length. The body thus prepared is then dipped in the glazing bath and after a short subsequent drying eriod, l'ired to the properfdegree of vitrication. f

As mentionedl above, one of the ends of the upper end. This l do ll propose to close then trimmed to remove the thin tube, preferably the, l

125 When one end is closed, any Hash-over that take place outsidebe incocuous or at' stantially flat.

the sheds formed bythe grooves 43are subf it should be considered desirable to provide dished sheds, the mold may be equipped with split rings. Thus as indicated in Fig. 13 themold 50 may be provided with split rings 51 of porous or absorptive material, sothatithe mold may be drawn away from the vformed tube after .the bondv is broken.

It understood that the increasing thickness of an insulator according tofI*` ig. 2 is secured byincreasing the outside diameter 0f the tube and the sheds. The inside diameter, by the nature ofl the process .must be uniform. i

The process, while more generally. applii tl'ie wall of a mold thereby causing the mold to move in the direction of the axis thereof.,

2. A process of molding material, which consists in forcing a plastic material against the inner wall of a mold thereby causing the mold to move in the direction of the axis thereof. i 3. A process of molding material, which consists in forcing the plastic material against-the walls ofl a-mold of absorpti-ve material and causing the mold'to move in the direction of .its axis. v

4. A process of molding material, which consists in forcing the lastic material against the walls of a mo d of absorptive` inaterial,'causing the mold to move in the direction of lts axis-and restralning the v material against flow in opposite axial direction and radially away from the mold.

. 5. A` process of molding material, which consists in forcing the plastic material" against the inner walls of atubular mold of .absorptive material causing the. mold to move in axial direction and restraining the material against flow in-opposite axial direction and radially away from the mold.

6. A process of molding material, Awhich 'n consists in forcing the `plastic material against the inner walls of a tubular mold ofl absorptive material into the space between the mold anda core, causing the mold to move in the axialy direction of the oreand restrainlng the material against flow 1n other directions.

7. A process ofmolding tubular bodies, which consists in forcing the -plastic material against the walls .of a'mold of absorp.

tive material under conditions such as to exert pressure on the mold in axial direction rmed quickly and contact with lthe latter.

and allowing the mold to move under thev said pressure.

8. A .process of 'molding tubular bodies,

lwhich. consists in forcing the plastic material partly radially and partly axially against the walls of a mold of absorptive material, allowing the mold to move under the pressure exerted against it by. the material and holding the material, at least dur-k ing a part ofy the travel thereof with the mold, in forced contact with the latter. 9. A process of molding tubular bodies,

whichconsists in forcing the plastic material partly radially and partly axially against the walls of a mold of absorptive material into the space between the mold and a. core and allowing the mold to move under the pressure exerted against it by the mate= rial.

10. In a process of making insulators, `the steps which consist in forming of absorptive material an axially divided tubular molti having on its inner surface. circular recesses defining sheds, forcing the plastic material radially outwardly from the center `against the Wall of the mold,causing the mold to inoveaxially and holding the. material, at least during apart of the travel thereof with the mold, in forced contact with the latter.

l1. Ina process of making insulators, the` steps `which consist in forminor offabsorp- Ative material an axially divided tubular mold having on its inner surface circular recesses defining sheds, forcing the plastic partly` in' axial direction and allowing the mold to move under the pressure of the material.

12. In a process of making insulators, thesteps which consi t informing of absorptive material an Y,axially divided tubular mold having on its inner surface circular recesses defining sheds, forcing" the plastic material outwardly from .the center against the `wall of the mold partly `in radial and partly in material outwardly from the center against 'tlie wall of the. mold partly in radial, and' axial direction', allowing the mold to move. I

under the pressure of the material and holding the material, at least during apart of the travel thereof with the mol in forced 13. In a process ofmaking insulators, the steps which consist in forinin tive materia-l Pan axiallyl divided tubular mold havingon itsinner surface circular recesses .defining sheds, forcing the plastic material outwardly from the center against the wall of. the mold partly`- in radial and partly in axial direction into the space-.be-

tween the mold and a central core and allowling the mold to move under the pressure of the material.

14. In a process of making insulators, the' absorp.

steps which consist in forming 'of tive material an axially divided tubular mold having on its inner surface circular recesses defining sheds, forcing the plastic material outwardly from the center against the wall of the mold partly in4 radial and partly in axial direction into the space between the mold and a central core, allowing the mold to move under the pressure of the material, and restraining the material against flow in opposite axial direction.

l5. Apparatus for molding material. comprising a tubular mold movable in axial direct-ion, a central core and means for forcing plastic material from the center partly radially and partly axially against the mold into the space between the latter and the core.

16.. Apparatus for molding material, comprising a tubular mold movable in axial direction, a central core` means for forcing plastic material from the center partly'raidially and partly axially against the mold into the space between the lat-ter and the core and. means for preventing the iow of the material in opposite axial direction.

17. Apparatus for molding material, comprising a mold of absorptive material movable in axial direction, a central core, means for forcing plastic material from the center` partly radially and partly axially against the mold into the space between the latter and the core, and meansjfor preventing the flow of the material in l'opposite axial direction.

18. Apparatus according to claim 17 in which .the means for forcing the material against the mold includes a generally coneshaped spreading element in advance of the core.

19. Apparatus according to claim 17 in which the means for forcing the material against the mold includes a generally coneshaped spreading element integral with the core and in advance thereof.

20. Apparatus for molding material, comprising a tube, a tubular mold absorptive material movably mounted on the tube, a core'projecting beyond the end of the tube, Y means in the ytube for mounting thercorek 5o centrally ofthe tube and means for feed-l ing plastic material' through the other end of the tube toward the core.v

21. Apparatus accordin to` claim 20 in which the end of the core dlrected toward the tube tapers toward the axis of the tube and defines means for forcing theplastic material outwardly from the center' against the wall of the mold.

22. Apparatus according to claim E20, in whichv the end of the core directed toward the tube tapers toward the axis of the tube and defines means for forcing the plastic material outwardly from the center against the wall of the mold and in which the means for mounting the core includes a stem extending from the tapering end of the core and a spider frame secured-in the tube for holding the stem and the core in position.

Q3. Apparatus for molding insulators, comprising an axially divided tubular mold of absorptive material having circular recesses-defining sheds, a core disposed in the axis of the mold, pressure means for supporting the mold for axial movement, means for feeding plastic material toward the space deiinedby the mold and the core, means in advance of the core for directing the material partly radially and partly ax- I ially against the walls of the mold and means for preventing iiowi of the material 80 rearwardly `away from the core.

24. Apparatus for molding insulators, comprising a tube, an axially .divided mold of absorptive material movably monted on the tube and normally projecting beyond one end thereof, a core 'projecting beyond the `same end of the tube, pressure means for feeding plastic material into the tube from the other end thereof and means'for directing the plastic material outwardly from the ycenter partly radially and partly axially against the walls of the mold, the latter having circular recesses defining sheds.

25. Apparatus for molding' insulators, comprising a tube, an axially divided mold of absorptive material movably mounted' on the tube and normally projecting beyond one end thereof and a core projecting beyond the same end of the tube, the mold having circular recesses defining sheds and a closed outer end provided with a perforartion, and means for forcing plastic material against the mold into the space between the latter and the core.

In testimony whereof, I affix my signature.

CARL G. KOPPITZ.

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