2,619,678
`D. E. CROOKER
`Dec. 2, 1952
`METHOD OF AND APPARATUS FOR THE MANUFACTURE OF NONSKID TIRE TREADS
`
`Filed Feb. 16, 1948
`
`2 SHEETS—SHEET 1 INVENTOR, .
`
`
`
`CG
`
`BY
`
`AITORNEYS.
`
`1
`1
`
`Mattel Ex. 2005
`Mattel Ex. 2005
`Dynacraft v. Mattel
`Dynacraft v. Mattel
`IPR2018-00042
`IPR2018-00042
`
`

`

`2,619,678
`D. E. CROOKER
`Dec. 2, 1952
`METHOD OF AND APPARATUS FOR THE MANUFACTURE OF NONSKID ‘TIRE TREADS
`Filed Feb. 16, 1948
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`

`Patented Dec. 2, 1952
`
`2,619,678
`
`UNITED STATES PATENT OFFICE
`
`2,619,678
`
`METHOD OF AND APPARATUS FOR THE
`MANUFACTUREOF NONSKID TIRE TREADS
`
`David E. Crooker, Ontonagon, Mich., assignor of
`one-half to Lloyd L. Felker, Marshfield, Wis.
`
`Application February 16, 1948, Serial No, 8,646
`26 Claims.
`(Cl, 18—18)
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`This invention relates to improvements in the
`method of and apparatus for the manufactureof
`non-skid tire treads.
`The tire industry has recognized the need for
`an automobile tire which will provide aedquate
`traction on icy streets or in other places where
`conventional automobile tires fail to grip, and
`are for that reason unsafe. Many types of con-
`struction have been proposed, and the type
`wherein metal
`traction augmenting members,
`such as coils are ‘molded longitudinally into the
`tread or rider strips of the tire has been found
`to have particular merit. Certain difficulties,
`however, have been encountered in the manu-
`facture of this type of tire.
`The original manufacture of a tire and a re-
`treading operation are very similar.
`In fact, the
`retreading operation involves some of same steps
`as original tire manufacture, and during these
`steps, very similar equipment is employed in both.
`In the curing stage of both operations the tire
`casing surrounds an inflatable annular core and
`is surrounded by a steam jacketed annular ma-~-
`trix. The core is inflated and the pressure there-
`from (which is similar to the action of an in-
`flated inner tube) forces the uncured rubber of
`the tire against the hot matrix. The matrix is
`formed on its tire engaging surface with a con-
`tour which corresponds to the contour desired on
`the finished tire. The uncured rubber is forced
`into the pattern of the matrix, and after a pre-
`determined period of exposure to the heat and
`pressure above mentioned, the curing of the rub-
`ber is complete and the tire is removed from
`the matrix.
`In the manufacture of tires having coils em-
`bedded in the threads thereof, a matrix having
`spaced circumferentially extending rectangular
`grooves has heretofore been used. The circum-
`40
`ferential
`rectangular grooves
`formed similar
`spaced circumferentially extending tread or rider -
`strips on the tire cured in the matrix.
`In order
`to embed coils in:the rider strips of the tire, the
`coils have been placed in the grooves of the mat-
`rix prior to the placement of the uncured tire
`within the matrix.
`It is very important that the
`wire coils be laterally centered in the rider strips
`of the finished tire and in the method as here-
`tofore proposed, difficulty has been encountered
`in maintaining the wire coils laterally centered
`in the rectangular grooves of the matrix,
`In
`order to have the coils laterally centered in the
`rider strips of the finished tire, the coils must be
`maintained in laterally centered position in the
`matrix grooves throughout the curing operation.
`
`2
`With the above in mind, the principal object
`of the invention is to provide a method of and
`apparatus for the manufacture of non-skid tire
`treads of the type having wire coils embedded
`therein, wherein the wire coils are maintained
`in laterally centered position in the grooves of
`the matrix throughout the curing operation.
`A further object of the invention is to provide
`a method of and apparatus for the manufacture
`of non-skid tire treads of the class described,
`wherein the wire coils are maintained in laterally
`centered position in the grooves of the matrix
`without requiring special tools or attachments
`in addition to those conventionally used.
`A further more specific object of the inven-
`tion is to provide an annulartire matrix or mold,
`the interior of which is formed with spaced cir-
`cumferentially extending grooves having the bot-
`tom surfaces of each groove formed with a longi-
`tudinally extending concavity, the deepest por-
`tion of said concavity being laterally centered in
`the groove.
`With the above and other objects in view, the
`invention consists in the improved method of and
`apparatus for the manufacture of non-skid tire
`treads, and all of the steps, parts and combina-
`tions incident thereto, and all equivalents thereof.
`A clear conception of the steps of the improved
`method and of the construction of the improved
`apparatus may be had by referring to the draw~
`ing accompanying and forming a part of this
`specification, wherein like reference characters
`designate the same parts in all of the views:
`Fig. 1 is a perspective view of a tire molding
`machine;
`Fig. 2 is a fragmentary transverse sectional
`view taken through a portion of the mold during
`a curing operation;
`Fig. 3 is an enlarged fragmentary transverse
`sectional view taken through a matrix embodying
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`_ preferred form of circumferential groove;
`an
`Figs. 4, 5, and 6 are enlarged fragmentary
`transverse sectional views taken through a mat-
`rix and showing three different modified forms
`of the improved circumferential groove.
`:
`Referring more particularly to Fig. 1 of the
`drawing, the numeral 5 indicates one type of tire
`molding machine having a stationary annular
`upper mold section 6 and having a movable an-
`nular lower mold section 7. The lower mold sec-
`tion 7 may be moved by any suitable actuating
`mechanism into registration with the upper mold
`section 6, and the sections may be removably
`55 bolted together by engagement of the bolts 8 and
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`160
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`3
`the nuts 9 of the lower section 7 with the lugs
`{0 of the uppersection 6.
`Each of the mold sections 6 and 7 is provided
`with an annular matrix section and with an an-
`nular steam jacket section extending around said
`matrix section and supporting the same. The
`upper Mold section 6 comprises the upper steam
`jacket 11 and the upper matrix section 12, and
`the lower mold section 1 comprises the lower
`steam jacket (3 and the lower matrix section (4.
`The matrix sections 12 and 14 are formed on their
`inner surfaces, as at 15 in Fig. 2, with a pattern
`corresponding to the tread to be formed on the
`tire which is to be cured therein.
`In the manufacture of non-skid tire treads hav-
`ing wire coils embeddedin therider strips thereof
`as heretofore proposed, a matrix having spaced
`rectangular grooves extending circumferentially
`around the inner surface thereof has been used.
`This type of matrix pattern produced a tread in
`the form of spaced rectangularly shaped longi-
`tudinally extending rider strips having substan-
`tially flat wearing surfaces. The coils have been
`inserted in the matrix grooves prior to the place-
`ment of the uncured tire in the matrix, and par- 9
`ticular difficulty has heretofore been encountered
`in attempts to maintain the coils in laterally
`centered position in the grooves of the matrix
`during the curing operation. There has hereto-
`fore been a tendency for the coils to assume a
`wavy configuration, or to be urged against one
`side of the groove by the force of gravity.
`In the present invention, in order to provide
`@ means for maintaining the coils in laterally
`centered position in the rectangular grooves of
`the matrix, the matrix is formed with a longi-
`tudinal concavity or channel 16 in the bottom of
`each of the spaced circumferentially extending
`grooves 17. The preferred form of concavity is
`shown in Figs. 2 and 3.
`It occupies only a por-
`tion of the bottom surface of the otherwise sub-
`stantially rectangular groove 17 and is laterally
`centered therein as shown. A modified form of
`the invention is shown in Fig. 4, wherein the
`concavity 16’ comprises the entire bottom of the
`groove 17. In the preferred form of the invention
`the radius of curvature of the concavity (6 is
`substantially equal to the radius of curvature of
`the outside of the coil 18 to be embedded in the
`rider strip of the finished tire.
`While it is preferred to use a longitudinal con-
`eavity which is curved in cross section, as shown
`in Fig. 3, any longitudinal recess that is milled
`or machined or otherwise provided in the bottoms
`of the rider strip grooves and which is capable
`of centering traction augmenting members such
`as springs is within the scope of the invention.
`Two of such modified shapes are indicated in
`Figs.5 and 6. In Fig. 5 the numeral 22 designates
`@ longitudinal concavity which is rectangular in
`eross section and which functions the same as
`the concavity 16, and the numeral 23 in Fig. 6
`designates a V-shaped concavity which functions
`the same as the concavity (6 of Fig. 3.
`In a retreading operation, when it is desired
`to manufacture a non-skid tread in accordance
`with the improved method, a matrix provided
`with spaced circumferentially extending grooves
`{1 of the type shown in Figs. 2 and 3 is used.
`One coil 18 for each groove I7 of the matrix is
`cut to a length slightly longer than the circum-
`ference of the base of the groove {1. Experience
`has shown that ‘a length of spring approximately
`four inches longer than the circumference of
`the base of the groove 17 is satisfactory. The
`4
`4
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`4
`18 are then placed in the respective
`springs
`grooves {1 with the ends abutting and with a side
`portion seated in the concavity 16 in the base of
`the groove (17, as shown in Fig. 3. Because of the
`outward pressure exerted by the springs {8 due
`to the fact that they are longitudinally com-
`pressed (having been cut four inches longer than
`the space they now occupy), the springs 18 main-
`tain themselves firmly seated in the concavities
`{6 and are thereby centered laterally in the
`grooves {T.
`After the springs 18 have been positioned in
`the grooves 11, a tire 19 to be retreaded, mounted
`on a suitable rim 20 and having inserted therein
`an inflatable annular bag or core 21, is prepared
`for
`the curing operation.
`This consists
`in
`smoothing off the wearing surface thereof and ce-
`menting to the smoothed surface a layer of un-
`cured rubber or “camelback.” The tire is then
`placed in axially centered position between the
`open halves {2 and 14 of the matrix. The lower
`mold section 7 is then brought up into registra-
`tion with the upper mold section and is bolted
`tightly thereto by means of the bolts 8, the nuts
`9, and the lugs {0. This brings the lower matrix
`section {4 in close registration with the upper
`matrix section [2.
`Steam is then introduced into the steam jackets
`{{ and 13, and the annular core or bag 21 is then
`inflated. The expanding pressures created by the
`core 21 expands the tire casing and forces the
`uncured rubber “camelback” into contact with
`the matrix pattern 15.. Said pattern consists of
`the spaced grooves {71 with the springs {9 seated
`in the concavities 16 of said grooves. Under the
`heat from the steam jackets 1{ and 13, and under
`the pressure from the core 21, the uncured rub-
`ber of the “camelback” flows into the grooves IT,
`into the concavities 16, and around the springs
`18, to conform to the matrix pattern 15 as shown
`in Fig. 2. With continued application of prede-
`termined amounts of heat and pressure for a pre-
`determined period of time, the uncured ‘“camel-
`back” becomes cured.
`It will be noted that dur-
`ing the entire curing operation, from the time of
`their insertion into the matrix, the springs {8
`remain firmly seated in the concavities 16 of the
`grooves {7. Due to the fact that portions of the
`convolutions of the coils project into the con-
`cavity 16, said portions necessarily project into
`the heated mold portions beyond the bottoms {7
`of the grooves. Thus heat from the portions 12
`and {4 of the mold is conducted by the metal of
`the coils into the rubber tread which is being
`formed. As a resulj a speedier and more uni-
`form cure is obtained. because of the position of
`the coils wherein portions project inwardly be-
`yond the bottoms 17 of the grooves. After the
`“camelback” has been cured, the steam is shut
`off from the jackets if and 13, the bag or core
`24 is deflated, and the lower mold section 7 is
`unbolted from the upper mold section 6 and
`lowered to the position of Fig.1. The retreaded
`tire 19 is then removed from the mold, and the
`rim 26 and core 2{ are also removed. The tire
`is then ready for use.
`Various changes and modifications may be
`made without departing from the spirit of the
`invention, and all of such changes are contem-
`plated as may come within the scope of the
`claims.
`What I claim is:
`1. In a tire molding machine, a matrix having
`its tread molding surface formed with at least
`one circumferentially extending groove having a
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`2,619,678
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`bottom wall and which is substantially rectangu-
`lar in cross section, the bottom wall of said groove
`being formed with a longitudinally extending
`concavity for receiving and positioning a circular
`traction augmenting member.
`2. In a tire molding machine, a matrix having
`its tread molding surface formed with at least
`one circumferentially extending groove having a
`bottom wall and which is substantially rectangu-
`lar in cross section, the bottom wall of said groove
`being formed with a laterally centered, longitu-
`dinally extending concavity for receiving and
`positioning a circular traction augmenting mem-
`ber.
`3. In a tire molding machine, a matrix having
`its tread molding surface formed with at least
`one circumferentially extending groove having a
`bottom wall and which is substantially rectangu-
`lar in cross section, the bottom wall of said groove
`being formed with a laterally centered, longitu-
`dinally extending concavity for receiving and
`positioning a circular traction augmenting mem-
`ber, said concavity having a radius of curvature
`which is not substantially longer than half the
`width of the groove.
`‘
`4. In a tire molding machine, a matrix having
`its tread molding surface formed with at least
`one circumferentially extending groove having a
`bottom wall and which is substantially rectangu~
`Jar in cross section, the bottom wall of said groove
`being formed with a laterally centered, longitu-
`dinally extending concavity for receiving and
`positioning a circular traction augmenting mem-
`ber, said concavity having a width less than that
`of the groove.
`5, A tire retreading device comprising a cylin-
`drical mold member having a plurality of axially
`spaced inwardly directed generally parallel cir-
`cumferential design forming ribs, and means car-
`ried by said member and disposed between each
`two adjacent ribs constructed and arranged to
`support and center a wire coil skid resisting
`means between each two adjacent ribs.
`6. The method of forming non-skid tire treads
`with the use of a tire molding machine of the
`type which has circumferential rider strip form-
`ing grooves comprising: longitudinally compress-
`ing elongated traction augmenting coils the con-
`volutions of which are of less diameter than the
`width of the rider strip forming grooves of the
`mold and which are of greater normal length
`than the internal circumference of the mold,
`placing the coils while thus compressed in said
`grooves With one coil in a groove, holding thecoils
`in laterally centered position in said grooves while
`the coils are compressed, and then while thus
`holding the coils forming a tire tread.
`7. The method of forming non-skid tire treads
`with the use of a tire molding machine of the
`type which has circumferential rider strip form-
`ing grooves comprising: longitudinally compress-
`ing elongated traction augmented coils the con-
`volutions of which are of less diameter than the
`width of the rider strip forming grooves of the
`mold and which are of greater normal length
`than the internal circumference of the mold,
`placing the coils while thus compressed in said
`grooves with one coil in a groove, holding the
`coils in laterally centered position in said grooves
`while the coils are compressed, causing uncured
`rubber to flow into the grooves and around said
`coils, curing said rubber, and continuing to hold
`the coils in centered position in the grooves un-
`til the rubber has been cured.
`8. A tire molding device comprising a cylin-
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`drical mold member having a plurality of axial-
`ly spaced inwardly directed circumferential de-
`sign forming ribs, and continuous centering
`means carried by said member and dispcsed be-
`tween each two adjacent ribs to support and
`center an elongated traction augmenting mem-
`ber which is of less dimension in a direction
`axially of the mold than the distances between
`ribs.
`9. A tire molding device comprising a cylindri-
`cal mold member having a plurality of axially
`spaced inwardly directed circumferential design
`forming ribs, said mold member having a cen-
`tering channel disposed between a pair of ad-
`jacent ribs, which channel is of a width less than
`the distance between ribs and serves to sup-
`port and center an elongated traction augment-
`ing member which is of less dimension in a di-
`rection axially of the mold than the distance be-
`tween ribs.
`10. A tire molding device comprising a cylin-
`drical mold member having a plurality of axially
`spaced inwardly directed circumferential design
`forming ribs, said mold member having a cen-
`tering channel disposed between a pair of ad-
`jacent ribs and depressed into the material of
`the mold member, which channelis of less width
`than the distance between ribs and serves to sup-
`port and center a wire coil skid resisting mem-
`ber which is of less diameter than the distance
`between ribs.
`11. A mold for tire treads comprising a cylin-
`drical body portion, and a pair of circumferen-
`tially extending ribs projecting inwardly from
`said body portion and having a circumferentially
`extending tread forming wall portion therebe-
`tween, said wall portion having a circumferen-
`tially extending and inwardly facing wire coil
`supporting and centering channel intermediate
`said ribs.
`12. A mold for tire treads comprising a cylin-
`drical body portion, and a pair of circumferen-
`tially extending ribs projecting inwardly from .
`said body portion and having a circumferentially
`extending tread forming wall portion therebe-
`tween, said wall portion having a cross-sectional
`shape which forms a channel having a width sub-
`stantially equal to the distance between ribs for
`receiving and centering an elongated traction
`augmenting member.
`13. A mold for tire treads comprising a cylin-
`drical body portion, and a pair of circumferen-
`tially extending ribs projecting inwardly from
`said body portion and having a circumferentially
`extending tread forming wall portion therehe-
`tween, said wall portion having a circumferen-
`tially extending and inwardly facing wire coil
`supporting and centering channel which is ar-
`cuate in cross-section intermediate said ribs.
`14, A mold for tire treads comprising a cylin-
`drical body portion, and a pair of circumferen-
`tially extending ribs projecting inwardly from
`said body portion and having a circumferentially
`extending tread forming wall portion therebe-
`tween, said wall portion having a circumferen-
`tially extending and inwardly facing wire coil
`supporting and centering channel which is rec-
`tangular in cross-section intermediate said ribs.
`15. A mold for tire treads comprising a cylin-
`drical body portion, and a pair of circumferen-
`tially extending ribs projecting inwardly from
`said body portion and having a circumferentiaily
`extending tread forming wall portion therebe-
`tween, said wall portion having a circumferen-
`tially extending and inwardly facing wire coil
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`supporting and centering channel which is v-
`shaped in cross-section intermediate said ribs.
`16. A mold for tire treads comprising a cylin-
`drical body portion, and a pair of circumferen-
`tially extending ribs projecting inwardly from
`said body portion and having a circumferentially
`extending tread forming wall portion therebe-
`tween, said wall portion having spaced circum-
`fenertially extending shoulders intermediate said
`ribs with the spacing between shouldersless than
`the spacing between ribs to center an elongated
`traction augmenting member which is of
`less
`width than the distance between ribs.
`17. A mold for tire treads comprising a cylin-
`drical body portion, and a pair of circumferen-
`tially extending ribs projecting inwardly from
`said body portion and having a circumferentially
`extending tread forming wall portion therebe-
`tween, said wall portion having a circumferen-
`tially extending and inwardly facing wire coil
`centering channel which is of less width than the
`distance between ribs.
`18. A mold for tire treads comprising a cylin-
`drical mold member having a plurality of axially
`spaced and inwardly directed design forming ribs
`which extend generally circumferentially of the
`member, a circumferentially extending wall por-
`tion between each pair of
`ribs and defining
`tread forming grooves therewith, each of said
`wall portions being shaped to provide a wire
`coil centering channel which has its greatest
`depth at the Jateral center of the groove where-
`by to center each coil with respect to a pair of
`design forming ribs of the mold member.
`19, A mold for tire treads comprising a cy-
`lindrical body portion having a plurality of axial-
`ly spaced and radially inwardly projecting flanges
`which extend generally circumferentially of the
`body portion and provide therewith the bottom
`and side walls of design forming grooves,
`the
`bottom of each groove having a circumferential-
`ly extending and inwardly facing wire coil sup-
`porting channel between each pair of groove
`forming flanges with the bottom of said chan-
`nel disposed radially outwardly from the bot-
`tom of the groove whereby to position and re-
`tain wire coils during the curing of a tread with
`a portion of each convolution of each coil pro-
`jecting radially outwardly of the normal road
`engaging tread surface.
`20. In a tire molding machine, a matrix hav-
`ing its tread molding surface formed with at
`jeast one circumferentially extending groove hav-
`ing a bottom wall, said bottom wall being formed
`with a longitudinally extending channel for re-
`ceiving and positioning an elongated traction
`augmenting member.
`21. In a tire molding machine, a matrix hay-
`ing its tread molding surface formed with at
`least one circumferentially extending groove hav-
`ing a bottom wall, said bottom wall being formed
`with a laterally centered, longitudinally extend-
`ing channel of less width than the width of the
`groove for receiving and positioning an elongated
`traction augmenting member.
`22. A mold for tire treads comprising a cy-
`lindrical body portion, and a pair of circum-
`ferentially extending ribs projecting inwardly
`from said body portion and having a circumfer-
`entially extending tread forming wall portion
`therebetween, said wall portion having a cir-
`cumferentially extending and inwardly facing
`wire coil supporting and centering channel the
`cross
`section of which is
`in the form of
`an are,
`the radius of said are being substan-
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`tially the same as the radius of a convolution of
`the wire coil to be supported, said channel be-
`ing located intermediate said ribs.
`23. A mold for tire treads comprising a cy-
`lindrical body portion adapted to be heated and
`having a plurality of axially spaced and radial-
`ly inwardly projecting flanges which extend gen-
`erally circumferentially of the body portion and
`provide therewith the bottom and side walls of
`design forming grooves;
`the bottom of each
`groove having a circumferentially extending and
`inwardly facing wire coil supporting channel be-
`tween each pair of groove forming flanges with
`the bottom of said channel disposed radially out-
`wardly from the bottom of the groove whereby
`to position and retain wire coils during the cur-
`ing of a tread with a portion of each convolu-
`tion of each coil projecting radially outwardly of
`the normal road engaging tread surface, each
`channel having its cross section in the form of
`an are with the radius of said arc substantially
`the same as the radius of a convolution of the
`wire coil to be supported, whereby the coils are
`centered in the grooves and serve to speed up the
`transfer of heat from the mold bodyportion in-
`to the tire tread to be formed.
`24. The method of forming non-skid tire treads
`with the use of a tire molding machine of the
`type which has a mold portion provided with cir-
`cumferential rider strip forming grooves having
`bottoms and having channels in said bottoms
`comprising: placing metal elongated traction
`augmenting members in said grooves with each
`groove accommodating one of said elongated
`traction augmenting members, causing portions
`of the traction augmenting members to project
`into the channels so that said portions project
`into the mold portion farther than the bottoms
`of the grooves andin laterally centered position
`in said grooves, heating the mold portions into
`which said portions of the traction augmenting
`members project, holding said elongated traction
`augmenting members in said position in said
`grooves, and then while thus holding the trac-
`tion augmenting members forming a tire tread
`while heat is being rapidly conducted into said
`tread by said projecting portions of the elongated
`traction augmenting members.
`25. The method of forming non-skid tire treads
`with the use of a tire molding machine of the
`type which has a mold portion provided with cir-
`cumferential rider strip forming grooves having
`bottoms and having channels in said bottoms
`comprising: placing metal coils in said grooves
`with each groove accommodating oneof said coils,
`causing portions of the convolutions of the coils
`to project into the channels so that said portions
`of the convolutions project into the mold portion
`farther than the bottoms of the grooves and in
`laterally centered position in said grooves, heat-
`ing the mold portions into which said ‘portions
`of the convolutions of the coils project, holding
`said coils in said position in said grooves, and
`then while thus holding the coils, forming a tire
`tread while heat is being rapidly conducted into
`said tread by said projecting portions of the con-
`volutions of the metal coils.
`26, The method of forming non-skid tire treads
`with the use of a tire molding machine of the
`type which has a mold portion provided with cir-
`cumferential rider strip forming grooves hay-
`ing bottoms and having channels in said bot-
`toms
`comprising:
`longitudinally compressing
`metal coils which are of greater normal length
`than the internal circumference of the mold, plac-
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`2,619,678
`
`9
`ing the coils while thus compressed in said grooves
`with one coil in a groove, causing portions of
`the convolutions of the coils to project into the
`channels so that said portions of the convolution
`project into the mold portion farther than the
`bottoms of the grooves while in laterally cen-
`tered position in said grooves, maintaining the
`coils in said position in said grooves while thus
`compressed, causing uncured rubber to flow into
`the grooves and around said coils, heating the 10
`mold portions into which said portions of the
`convolutions of the coils project to cure said rub-
`ber, and continuing to thus hold the coils in the
`grooves until the rubber has been cured while
`heat is being rapidly conducted into said rubber 15
`
`10
`by said projecting portions of the convyolutions
`of the coils.
`
`DAVID E, CROOKER.
`
`REFERENCES CITED
`
`The following references are of record in the
`file of this patent:
`UNITED STATES PATENTS
`Date
`Name
`Hawkinson .------. Mar. 17, 1936
`Rihn et al. ---.--.--- Apr. 25, 1939
`Hawkinson _....----- Jan. 18, 1944
`COOKS? scoee Aug. 16, 1949
`
`Number
`2,034,618
`2,155,906
`2,339,696
`2,479,474
`
`7
`
`