CA1036766A - Tire curing press - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A tire curing press including a plurality of hy-draulically lingitudinally adjustable tensioning bolt assemblies.
The tensioning bolt assemblies are adjustable in length by an amount limited to about a length equal to the longitudinal thermal expansion of the portions of the tire curing press clamped there-by during the curing operation. Adjustable mechanical clamping means is carried by the tension bolt assemblies for mechanically releasably engaging the bolt assemblies with respect to at least one of the press portions to permit removal of the press cover portion from the base portion. Means is provided for supplying hydraulic fluid at a constant pressure to each of the ternsioning bolt assemblies to effect hydraulic clamping. The bolt assem-blies are hydraulically longitudinally extensible by at least a portion of the limited longitudinal adjustable length upon release of the hydraulic fluid pressure to facilitate release of the clamping means while preventing opening of the mould in the event of a failure of the hydraulic fluid supply.

Description

FIELD OF INVENTION
Thi~ invention relates to tire curlng pre~ses. In particular, thls invention relates to an improvement in a tlre curing preæs whlch ~acllitate~ the opening o~ the pres~ after the cure has been completed.
PRIOR A~T
The conventional tire curing press consi~s o~ a b~se portion and a removable cover portlon which, in u~e, enclose a tire ouring mould which is in two halves. To use this apparatus, one halP o~ the mould 1~ mounted on the base portion of the tlre curing press and the green tire is located in this halr o~ the mould and the other hal~ o~ the mould 18 then located over the rlrst half with the green tire located therebetween. The cover i8 then positioned over the base wlth the mould located thereon.
The mould ls then hydraullcally closed by means of a ram whlch elevates the mould lnto engagement wlth the cover and serves to hydraulically malntaln the mould in a closed position. In this type of apparatus, the base portions and the cover portlons of the tire curing press are generally made ~rom metal castings.
These cast components are expensive to manuracture. In addition, the hydraullc lifting mechansim required ~or elevating the moulds to the closed position i9 very expen~ive to manu~acture and malntain.
In attempting to construct a tire curing pre~ whlch i8 ~abrlcated from components which are welded together and in whlch the hydraullc mould closing apparatus i~ eliminated, dl~iculty has been encountered in attempting to release the mechanical clamplng mechanisms after the curing operation as a result of the thermal expan~lon of the mould during the curing operation. It has been found that i~ ~lmple mechanical clamplng bolt~ are extended between the base portlon and the cover portion 80 as to clamp the two halves o~ the mould therebetween, after 1. .

the application Or a ~ur~icient clamping ~orce to clo~e the two mould halves when cold, it i8 extremely dlfficult to re-lea~e the clamplng bolts a~ter the curing operation has been completed bec~u~e Or the thermal expansion o~ the mould.
SUMMARY OF ~HE INVENTION
The pre~ent invention overcomes these difficulties by providing a plurallty of hydraulically longltudinally ad~ustable tensioning bolt assembl1es ~or securing the base portion and the cover portion of a tire curing pre!ss to~ether in a position clamplng the tire curing mould therebetween.
Aocordlng to an embodiment o~ the present invention, the tire curing press comprlses a press base portlon, a tire curing mould, a press cover portlon adapted to extend over the tire curlng mould to be secured with respect to the base portion in a position clamping the tlre during mould cloQed therebetween, a plurallty o~ hydraulically longitudinally ad~ustable tenaioning bolt as3emblles arranged at spaced intervals about the base portlon ~or securing the press port10ns together in a posltion closlng said mould~ said bolt as~emblies being hydraulically longitudinally adJustable in length by an amount limited to about a length equal to the longltudinal thermal expan~ion of the portions o~ the tire curing press clamped therebetween during the curing operation. adJustable mechanical clamping mean~ is carried by the tensionlng bolt assemblies for mechanically re-lea~ably engaging the bolt a~emblies with respect to at lea~t one Or the pre~ portlons to permit removal of the press cover portion ~rom the base portion, means 18 provlded for supplylng hydraullc fluid at constant pressure to each of the tensioning bolt assemblies to e~ect hydraulic clamping, the bolt a~semblieæ
belng hydraulically longitudinally exten3ible by at least a portlon o~ the limlted longltudlnal ad~ustable length upon release of the hydraullc fluid pre~sure to facilitate release o~
the clamping means while preventlng opening o~ the mould in the event of a fallure o~ the hydraulic fluid ~upply.

PREFERRED EMBODIMENT
The invention will be more clearly under~tood arter re~erence to the following detalled ~peclfication read in conJunction with the drawlngs wherein Figure 1 is an exploded plctorlal vlew of a tlre curlng pres~ accordlng to an embodiment of the pre~ent ln~entlon;
Flgure 2 is an enlarged exploded view of a hydraulic-all~ longitudlnally adJuatable tensionlng bolt as~embly;
Flgure 3 18 a partially sectloned ~ront vlew Or an assembled tensioning bolt assembly according to an embodiment Or the pre~ent inventlon; and Flgures ~ to 8 are dlagrammatlc lllustratlon~ Or the variou~ positlons o~ the tenslonlng bolt as~emblles in use.
Wlth rererence to the drawings. re~erence numeral 10 re~ers generally to a tire curlng press according to an embodlment o~ the present lnvention. The tlre curing press comprises a pre~ base portion 12, a press cover portion 14, a lower tire curing mould section 1~, an upper tlre curlng mould section 18 and a ~pacer plate 20. The press base portion 12 and the pres~
cover portion 14 are preferably ~ormed ~rom rabricated steel plate.
The press base portion 12 has a bottom wall plate 22 and an upper wall plate 24 spaced above one another by a cy-lindrical outer wall 2~ and a cylindrical rein~orcing column 28.
Arcuate shaped ~pacer plates 30 are mounted on the upper surface Or the upper plate 24 o~ the base member 12 to center the lower mould halr 1~ thereon. A resilient sealing member 32 is located between circum~erential extending sealing rings 34 which extend about the peripheral edge Or the upper plate 24 to sealingly engage the press cover portion 14 as wlll be described herein-arter .
The press cover portion 14 consists of a cylindrical ~36766 ovter wall 3~ which has an annular sealing ~lange 38 at the lower end thereof ~dapted to engage the resllient seallng member 32 of the base when the cover is clamped agalnst the base. An upper wall 40 i8 located inwardly from the upper end o~ the cylindrlcal wall 3~. The upper wall 40 co-operates wlth the cylindrical wall 3~ to ~orm the chamber 42 therebetween.
The upper wall 40 1~ rein~orced by a plurality o~ I-beams 44 which radlate from a central cyllndrical support 4~. Tubular ~leevQs 48 are mounted in and open longitudinally through every second rein~orclng beam 4~. Short spacer blades 50 extend downwardly rrOm and radially Or the lower race Or the wall 40.
The ridges rormed by these ~pacer blades 50 serve to ~pace the spacer blade 20 downwardly ~rom the top wall 40 to permit ~ree circulation of the heated atmosphere within the chamber 42 during the curing operation.
The spacer plate 20 is ~ormed wlth a plurallty o~
passageways 52 whlch open therethrough. The upper mo~ld section 18 i8 ~ormed with a plurality of threaded passages 54 which are aligned with the passages 52 and adapted to receive threaded bolts 5~ which extend through the tubular sleeves 48. The bolts 5~ serve to mount the upper mould halr 18 on the press cover portion 14.
The upper and lower mould portions each have a mould cavity 58. The press cover portion 14 has a plurality o~ longit-udinally extendlng rein~orclng plates ~0 arranged in pairs about the periphery thereo~. A transverse plate ~2 extends between adJacent pairs o~ reinrorcing plates ~0 and i8 provided with a U-shaped ~lot ~4 opening inwardly there~rom.
The press base portlon 12 is releasably secured with respect to the press cover portion 14 by means of a plurality o~
hydraullcally longitudlnally ad~ustable tensioning bolt assemblies ~.

10367~6 With reference to Flgure 2 of the drawlnga, it wlll be ~een that each of the assemblleq ~;~ consi~ts o~ a U-shaped bracket generally identi~ied by the reference numeral ~8 whlch is mounted on the outer wall 2~; of the base portlon 12. The U-shaped bracket ~8 has a palr of opposltely dl~posed ~lde walls ~9 and a base wall 70. A pair o~ spacer plates 72 are mounted on oppo~ite side walls B9 and longitudinally elongated pas~age3 74 open through the ~ide walls ~9 and the spacer plates 72.
A U-shaped ¢levis 7fi iB adapted to ~it about the U-shaped bracket 74. ~he clevi~ 7~ has a pair oP oppo~itely dlspo~ed slde walls 78 and a bottom well 80. The clevis 7~ ls reinforced by a palr o~ U-shaped reinforclng brackets 82. Passages 84 open through the opposltely dlsposed side walls 78 and a plvot pin 8~ 18 ad~pted to flt ln a close-fitting relatlonshlp wlthin the pas-sages 78. The plvot pin 8~ has a shallow transverse slot 88 formed adJacent one end thereof. A clamplng plate 90 i8 adapted to be mounted on the outer face Or one of the side walls 78 by means of a mountlng bolt 92 ls threadably engageable wlthin the passage 94 eo that the plate 90 pro~ects lnto the ~lot 88 formed in the pivot pin 8~ to ~ecure the pivot pin agalnst longltudlnal and rotational movement wlth respect to the clevis 7~.
A clamping bolt 9~ has a head portion 98 forrQed wlth a through passage 100 which is adapted to receive the plvot pln 8~ in a close-~itting sliding relatlonshlp. The upper end of the bolt 9~; is threaded to recelve a clamping nut 102.
Wlth reference to Flgure 3 of the drawings, lt will be seen that a face plate 104 i8 mounted on the under sur~ace of the transver~e plate 70. The base plate 104 has an upwardly concave su~face 10~. A cylinder 108 i~ mounted in the bottom of the clevis 7~ and opens upwardly therefrom. A piston 110 i3 slldably mounted ln the cyllnder 108 and ha~ a pi~ton ring 112 engaglng the wall of the cyllnder 110. The upper end 114 of the loæ766 piston has a convex curvature corre~ponding to the concave curvature of the surface 10~ Or the ~ace plate 104. A passage 11~ extends through the plate 80 Or the clevis and the end closure wall o~ the hydraulic cylinder 108. The pa~sage 11 i8 connected to a source Or hydraulic rluid by mean~ Or a conduit 118.
An important feature Or the present lnvention is that the elongated length L of the passages 84 is greater than the diameter D Or the plvot pin 8~ by an amount which i9 equ~l to about the longitudinal thermal expan~ion o~ the portions Or the tire curin~ press assembly which extend therebetween when the pre~s ls as~embled and heated to the required curing temperature.
It will be understood that the longitudinal thermal expansion of the tire press will be a function Or the structure of the tire press which may vary ~rom one tire press to another.
The operation of this apparatus will be more clearly described with rererence to the diagrammatlc illu~trations of Figure~ 4 to 8 inclusive. In the conditlon ~hown in Figure 4, no hydraulic ~luld ls ~upplled to the hydraullc cylinder and the piston 110 18, therefore, in a lowered position. Similarly, the nut 102 does not engage the bolt 9~ and ls ~ree ~rom the plate ~2 of the cover. In thls condltion~ the weight Or the clevis 7~ lowers the pin 8~ into engagement wlth the lower surPace o~ the elongated openings 84. In the first step Or closing the mould, a green tire is located in the bottom hal~
Or the tire mould 1~ which is mounted on the pre~ base portion 12.
The press cover portion wlth the upper half of the tire curing mould mounted thereon is lowered into a po~ition where the top hal~ of the mould 18 rests on the bottom hal~ o~ the mould 15.
The bolt assemblies ~ are then positioned as shown ln Figure 4 by pivotlng the bolt 9~ to a position wherein it extends through the slot ~4 rormed in the plate ~2. The nut 102 is then applied to the bolt 9~ and tightened in the direction of the ~036766 arrow A to a su~ficient extent to ralse the pivot pin 8~ to a position disposed substantially centrally with respect to the helght of the elongated passages 84 as shwon ln Figure 5 of the drawlngs. Hydraullc fluid is then supplied by way of the conduit 118 to the cylinder 108. The hydraullc ~luid raises the piston 110 lnto engagement wlth the plate 104 and thereafter the hydraulic M uld acts to pull the clevi~ 7~ downwardly 80 that the plvot pin 8~ moves downwardly wlthln the elongated passages 84 to a positlon at or adJacent the lower end o~ the elongated 810ts 84.
In this conditlon, the cover portion is secured wlth respect to the ba8e portlon by the force of the hydraulic ~luid exerted onthe plston 110 so that the closing force3 applied to the mould halves 1~ and 18 are unlform and may be sufficient to malntain the mould halves in a full closed conditlon during the early stages of the curlng operatlon. In thls respect, the provlsion o~ the hydraulic assemblies o~ the present lnventlon enables greater lnltial loading than was previously posslble by means Or a straight mechanical clamplng assembly. If a mechanical clamplng assembly was employed, it would not be possible to apply th~ forces requlred to close the mould during the early stages Or the curing operatlon without overloading the cl~mping bolts as a result of subequent heatlng during the entire curing operation. Furthermore, as prevlously indicated, considerable difflculty would be experienced ln attemptlng to release these clamplng bolts after the curlng operatlon until the tire press had cooled to an extent that it contracted to its original length.
The difflculties relating to the overloading of the tensioning bolts are overcome by the present invention as shown in Figure 7 o~ the drawings by reason of the ~act that thermal expansion o~ the asse~bled tire press reacts against the constant pressure in the hydraulic cylinder 80 that the clevis 7~ is permitted to move upwardly as shown ln Figure 7 of the drawings.
By reason of the fact that the passages 84 are longltudinally elongated to an extent whlch i~ prererably slightly greater than the longitudlnal thermal expanslon Or the portions Or the tlre press clamped therebetween, the plvot pln 8~ wlll move upwardly as the tlre presæ expand~ to a position spaced slightly below the upper end of the pa~sages 84. The ~pace between the plvot pin 8~ and the upper end Or the elongated opening~ 8~,when in the condition prevlously de~cribed with re~erence to Figure 7 o~ the drawing~. is such that ln the event Or a failure of the supply o~ hydraullc ~luid, the pivot pin 8~ would eng~ge the upper end Or the opening 84 and serve to prevent opening Or the press. It should be noted that during the curlng operatlon, very substantlal pressures are built up ln the tlre curing press and lr the clamplng mechansim did not lncorporate a mechanical stop, the cover could be blown o~ the base with catastrophic re~ults. The ~act that the fixed side walls ~9 o~ the U-shaped bracket ~8 serve to llmlt the upward movement of the pivot pin 8~ is lmportant as it serves to prevent separation o~ the cover and the base ln the event o~ a loss of hydraulic pressure.
A~ter the curlng operation has been completed, the æupply o~ hydraullc rluid to the ¢ylinder 108 is interrupted wlth the result that the pivot pin 8~ ls ~ree to move upwardly to engage the upper edge Or the opening 84, as shown in Figure 8 of the drawings. As a reæult, a considerable portlon o~ the ten~lonlng load applied to the bolt 9~ ls relieved and the nut 102 may be slackened off wlthout dl~iculty by rotatlon in the dlrectlon of the arrow B. It wlll be seen that lt ls the pro-vlslon of the gap between the pivot pin 8~ and the upper edge Or the pas~ages 84 when in the loaded condition illustrated in Figure 7 which permits the assembly to aæsume the contracted posltion illustrated ln Flgure 8 of the drawing~ wherein the nut102 may be easlly released.

103~766 From the aforegoing it will be a~parent that the present invention provides an improved tire curing press structure which incorporates h~draulically longitudinally ad~ustable tensioning bolt assemblies which permit full loadlng of the tire press moulds during the initlal sta~es Or the tire curing oper-ation while also provldlng a structure whlch facilltates the re-lease o~ the clamping assem~l~es after the curing operation has béen completed wlthout awaltln~ contraction Or the structure of the tire press res~ltln~ from coollng after curlng.
By way of example and wlthout limitlng the scope Or the present inventlon, lt has been found that in a tire press deslgned to accommodate loads sultable for uæe in curlng tires up to 36 x 51 having about 118" external diameter, the length L
Or the elongated passage 84 may equal 4-3/4" while the diameter D Or the pivot pins 86 may be 4-1/2". It has been found that by provlding a longitudinal clearance equal to about 1/4", there is adequare clearance to permit the required ad~ustment of the longitudinally ad~ustable bolt assemblies to accommodate both the closing and opening functlons whlle providlng the safety Or a structure which wlll not permlt openlng Or the mould in the event Or a failure ln the ~up~ly Or hydraullc fluld.
Various modiflcations Or the present lnventlon will be apparent to those skllled ln the art wlthout departing from the scope Or the inventlon. For example, the structure of the piston 110 is shown in the present invention as including a dome-shaped inner end to permit mounting of the piston wlthout reauiring a carefully aligned piston and piston rod assembly. Nevertheless, a modified piston assembly could be provided if required. These and other modifications Or the present lnvention will be apparent to those skilled ln the art without departin~ from the scope of the lnventlon.

Claims (6)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A tire curing press comprising (a) a press base portion, (b) a tire curing mould, (c) a press cover portion adapted to extend over said tire curing mould to be secured with respect to said base in a position clamping said tire curing mould closed therebetween, (d) A plurality of hydraulically longitudinally ad-justable tensioning bolt assemblies arranged at spaced intervals about said press portions for securing said press portions to-gether in a position closing said mould, (e) said bolt assemblies being hydraulically longitud-inally adjustable in length by an amount limited to about a length equal to the longitudinal thermal expansion of the por-tions of the tire curing press clamped thereby during the curing operation, (f) adjustable mechanical clamping means carried by said tension bolt assemblies for mechanically releasably engaging said bolt assemblies with respect to at least one of said press portions to permit removal of said press cover portion from said press base portion, (g) means for supplying hydraulic fluid at constant pressure to each of said tension bolt assemblies to effect hydraulic clamping, (h) said bolt assemblies being hydraulically longi-tudinally extensible by at least a portion of said limited longitudinal adjustable length upon release of said hydraulic fluid pressure to facilitate release of said clamping means while preventing opening of said mould in the event of a failure of said hydraulic fluid supply.

2. A tire curing press as claimed in Claim 1 wherein said tensioning bolt assemblies consist of; a fixed portion se-cured to said press base portion and a reciprocating portion mounted on said fixed portion for reciprocation relative thereto, an expansible hydraulic chamber formed between said fixed and reciprocating portions adapted to permit said limited longitudinal extension of said tensioning bolt assemblies.

3. A tire curing press as claimed in Claim 2 wherein said reciprocating portion includes mechanical stop means bearing against said stationary portion when said tensioning bolt assembly is in a fully extended position to prevent further longitudinal extension of said tensioning bolt assembly.

4. A tire curing press as claimed in Claim 3 wherein said reciprocating portion includes a clamping bolt having one end projecting towards said press cover portion, said one end being threaded, said adjustable mechanical clamping means con-sisting of a threaded nut mounted on said threaded end portion of said bolt.

5. A tire curing press as claimed in Claim 4 wherein the other end of said bolt is pivotally mounted with respect to the remainder of said reciprocating portion to pivot about a laterally extending axis in a direction away from said press cover portion.

6. A tire curing press comprising (a) a press base portion, (b) a tire curing mould, (c) a press cover portion adapted to extend over said mould to be secured with respect to said base portion in a position clamping said tire mould closed therebetween, (d) a plurality of mounting lug sets secured to said base portion at spaced intervals thereabout, said lug sets each having a downwardly directed support surface, (e) a piston member mounted on each of said lug sets and projecting downwardly from said support surface thereof, (f) a hydraulic cylinder having a chamber opening up-wardly over each of said piston members and slidable with respect thereto, input passage means opening into each of said chambers, (g) a support frame extending adjacent each of said mounting lugs and supporting said cylinders with respect to their associated pistons, (h) passage means opening laterally through each of said lug sets, locking pin means extending laterally from each of said frame members through said passage means of its assoc-iated lug set, said passage means of said lug sets being pro-portioned to permit vertical movement of said locking pins to an extent limited to about a length equal to the longitudinal thermal expansion of the portions of the tire press clamped therebetween during the curing operation, (i) locking bolt means having one end mounted on each of said locking pin means, each of said bolts projecting upwardly from its associated locking pin means and being threaded at the other end thereof, (j) locking nut means mounted on said other end of said bolt and adapted to engage said cover member to close said mould in use, and (k) means for supplying hydraulic fluid to said chambers of said hydraulic cylinders to hydraulically expand the chamber formed between said piston and said cylinder to an extent at least equal to half the travel permitted by the clearance provided between the locking pin means and said passage means of said lugs.