`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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`2 SI‘IEFJTS—SHEET 1
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`Mattel Ex. 2005
`Mattel Ex. 2005
`Dynacraft v. Mattel
`Dynacraft v. Mattel
`|PR2018—00042
`IPR2018-00042
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`
`
`Dec. 2, 1952
`
`D. E. CROOKER
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`2,619,678
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`METHOD OF AND APPARPATUS FOR THE MANUFACTURE OF NONSKID ITIRE TREADS
`
`Filed Feb. 16, 1948
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`2 SMTWT 2
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`Patented Dec. 2, 1952
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`2,619,678
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`UNITED STATES PATENT OFFICE
`2,619,678
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`METHOD OF AND _APPARATUS FOR THE
`MANUFACTURE OF 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.
`(01. 18—18)
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`With the above in mind, the principal object
`This invention relates to improvements in the
`of the invention is to provide a method of and
`method of and apparatus for the manufacture of
`non-skid tire treads.
`apparatus for the manufacture of non—skid tire
`treads of the type having wire coils embedded
`The tire industry has recognized the need for
`therein, wherein the wire coils are maintained
`an automobile tire which will provide aedquate
`in laterally centered position in the grooves of
`traction on icy streets or in other places where
`the matrix throughout the curing operation.
`conventional automobile tires fail to grip, and
`A further object of the inventiOn is to provide
`are for that reason unsafe. Many types of con-
`a method of and apparatus for the manufacture
`struction have been proposed. and the type
`of non-skid tire treads of the class described.
`wherein metal
`traction augmenting members.
`wherein the wire coils are maintained in laterally
`such as coils are-molded longitudinally into the
`centered position in the grooves of the matrix
`tread or rider strips of the tire has been feund
`without requiring special tools 0r attachments
`to have particular merit. Certain difficulties,
`in addition to those conventionally used.
`however. have been encountered in the manu-
`A further more specific object of the inven-
`facture of this type of tire.
`tion is to provide an annular tire matrix or mold,
`The original manufacture of a tire and a re-
`the interior of which is formed with spaced cir—
`treading operation are very similar.
`In fact, the
`cumferentially extending grooves having the bot-
`retreading operation involves some of same steps
`tom surfaces of each groove formed with a longi-
`as original tire manufacture, and during these
`tudinally extending concavity, the deepest por-
`steps. very similar equipment is employed in both.
`tion of said concavity being laterally centered in
`In the curing stage of both operations the tire
`the groove.
`casing surrounds an inflatable annular core and
`With the above and other objects in view, the
`is surrounded by a steam jacketed annular ma-
`invention consists in the improved method of and
`trix. The core is inflated and the pressure there-
`apparatus for the manufacture of non-skid tire
`from (which is similar to the action of an in-
`treads, and all of the steps, parts and combina-
`flated inner tube)' forces the uncured rubber of
`tions incident thereto, and all equivalents thereof.
`the tire against the hot matrix. The matrix is
`A clear conception of the steps of the improved
`formed on its tire engaging surface with a con-
`method and of the construction of the improved
`tour which corresponds to the contour desired on
`apparatus may be had by referring to the draw-
`the finished tire. The uncured rubber is forced
`ing accompanying and forming a part of this
`into the pattern of the matrix. and after a pre-
`specification, wherein like reference characters
`determined period of exposure to the heat and
`designate the same parts in all of the views:
`pressure above mentioned. the curing of the rub-
`Fig. 1 is a perspective view of a tire molding
`ber is complete and the tire is removed from
`machine;
`the matrix.
`Fig. 2 is a. fragmentary transverse sectional
`In the manufacture of tires having coils em-
`view taken through a portion of the mold during
`bedded in the threads thereof. a matrix having
`a curing operation;
`spaced circumferentially extending rectangular
`Fig. 3 is an enlarged fragmentary transverse
`grooves has heretofore been used. The circum-
`sectional view taken through a matrix embodying
`ferential
`rectangular grooves
`formed similar
`the1 preferred form of circumferential groove;
`an
`spaced circumferentially extending tread or rider -
`strips on the tire cured in the matrix.
`In order
`Figs. 4, 5, and 6 are enlarged fragmentary
`to embed coils 'in- the rider strips of the tire, the
`transverse sectional views taken through a mat-
`coils have been placed in the grooves of the mat-
`rix and showing three different modified forms
`rix prior to the placement of the uncured tire
`of the improved circumferential groove.
`'
`within the matrix.
`It is very important that the
`Referring more particularly to :E‘ig. 1 of the
`wire coils be laterally centered in the rider strips
`drawing, the numeral 5 indicates one type of tire
`of the finished tire and in the method as here—
`molding machine having a stationary annular
`tofore proposed, diniculty has been encountered
`upper mold section IE and having a movable an-
`in maintaining the wire coils laterally centered
`nular lower mold section 1'. The lower mold sec-
`in the rectangular grooves of the matrix.
`In
`tion 1 may be moved by any suitableactuating
`order to have the coils laterally centered in the
`mechanism into registration with the-upper mold
`rider strips of the finished tire, the coils must be
`section 6. and the sections may be removably
`maintained in laterally centered position in the
`matrix grooves throughout the curing operation. 55 bolted'together by engagement of the bolts 3 and
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`the nuts 5 of the lower section 1 with the lugs
`ID of the upper section '5.
`Each of the mold sections [1' and 'l‘ 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 Ii comprises the upper steam
`jacket ll and the upper matrix section 12. and
`the lower mold section 1 comprises the lower
`steam jacket [3 and the lower matrix section it.
`The matrix sections [2 and I4 are formed on their
`inner surfaces, as at IS 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 noniskid tire treads hav-
`ing wire coils embedded in the rider 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-
`ticular diiflculty 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
`a 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 IS in the bottom of
`each of the spaced circumferentialiy extending
`grooves IT. 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 l1 and is laterally
`centered therein as shown. A modified form of
`the invention is shown in Fig. 4. wherein the
`concavity I6’ comprises the entire bottom of the
`groove II. In the preferred form of the invention
`the radius of curvature of the concavity IE is
`substantially equal to the radius of curvature of
`the outside of the coil 13 to be embedded in the
`rider strip of the finished tire.
`While it is preferred to use a longitudinal con-
`cavity 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
`'a. longitudinal concavity which is rectangular in
`cross section and which functions the same as
`the concavity (E. and the numeral '23 in Fig. 6
`designates a V-shaped concavity which functions
`the same as the concavity I6 of Fig. 3.
`In a ret'reading 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
`11 of the type shown in Figs. 2 and 3 is used.
`One coil
`II! for each groove [1 of the matrix is
`cut to a length slightly longer than the circum-
`ference of the base of the groove I'I. Experience
`has shown that 'a length of spring approximately
`'four inches longer than the circumference of
`the base of the groove IT is satisfactory. The
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`I8 are then placed in the respective
`springs
`grooves 11' with the ends abutting and with a side
`portion seated in the concavity It in the base of
`the groove H. as shown in Fig. 3. Because of the
`outward pressure exerted by the springs I8 due
`to the fact that they are longitudinally com-
`pressed (having been cut four inches longer than
`the space they now occupy}, the springs I8 main-
`tain themselves firmly seated in the concavities
`IE and are thereby centered laterally in the
`grooves I'I.
`After the springs l8 have been positioned in
`the grooves 11-. a the IS 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 I2 and ill of the matrix. The lower
`mold section 1 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 to. This brings the lower matrix
`section I4 in close registration with the upper
`matrix section l2.
`Steam is then introduced into the steam jackets
`I and 13. and the annular core or bag 2: is then
`I
`inflated. The expanding pressures created by the
`core 2| expands the tire casing and forces the
`uncured rubber “camelbac ” into. contact with
`the matrix pattern IE. Said pattern consists of
`the Spaced grooves H with the springs l3 seated
`in the concavities it of said grooves. Under the
`heat from the steam jackets I
`I and I3. and under
`the pressure from the core 2 I. the uncured rub-
`ber of the “camelback” flows into the grooves 11.
`into the concavities I6, and around the springs
`I8, to conform to the matrix pattern l5 as shmvn
`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 I6 of the
`grooves I'I. 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 H
`of the grooves. Thus heat from the portions I-2
`and [4 of the mold is conducted by the metal of
`the coils into the rubber tread which is being
`formed. As a result a speedier and more uni—
`form cure is obtained because of the position of
`the coils wherein portions project inwardly be-
`Yon'd the bottoms ll 'of the grooves. After the
`“Camelba'ck” has been cured. the steam is shut
`off from the jackets II and 13, the bag or core
`2|
`is deflated, and the lower mold section 'I
`is
`unbolt'ed from the upper mold section 6 and
`lowered to the position of Fig. 1. The retreaded
`tire is is then removed from the mold, and the
`rim 2!! 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 surf-ace formed with at least
`one circumferentially extending groove having a
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`2,619,673
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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 cn'cumferentially 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—
`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 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 the coils
`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 or 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.
`B. 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 disposed 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 or 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 con—
`tering channel disposed between a pair of ad-
`jacent ribs, which channel is or 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 channel is 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 circumferem
`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 therebe-
`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 circumferentially
`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 circumieren-
`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-'
`ienertially extending shoulders intermediate said
`ribs with the spacing between shoulders less 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 circumferem
`tially extending ribs projecting inwardly from
`said body portion and having a circumferentislly
`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 or the
`member, a circumferentially extending wall por-
`tion between each pair of
`ribs and defining
`tread forming grooves therewith, each or said
`wall portions being shaped to provide a wire
`coil centering channel which has its greatest
`depth at the lateral 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.
`23. In a tire molding machine, a matrix hav-
`ing its tread molding surface formed with at
`least one circum‘ferentially extending groove hav-
`ing a bottom well, said bottom well 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 hav—
`ing its tread molding surface formed with at
`least one circumferentially extending groove hav-
`ing a. bottom well. 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 pesitioning 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 arc.
`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 cn'cumferentlally 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 arc with the radius of said are 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 body portion 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 and in 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 tree-
`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 one of 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 hav—
`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-
`
`
`
`53,619,678
`
`10
`by said projecting portions of the conVolutions
`of the coils.
`
`DAVID E. CROOKER.
`
`REFERENCES CITED
`
`The following references are of record in the
`file of this patent:
`UNITED STATES PATENTS
`
`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 Rater-ally 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
`mold portions into which said portions of the
`convolutions of the coils project to cure said rub-
`bar. 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
`
`0 Number
`2,034,618
`2,155,906
`2,339,696
`2,479,474
`
`Date
`Name
`Hawkinson ________ Mar. 17, 1936
`Rihn et ai ___________ Apr. 25, 1939
`Hawkinson __________ Jan. 13, 1944
`Crocker- ____________ Aug. 16, 1949
`
`7
`
`