US2783497A - Apparatus for heat treating latex articles - Google Patents

Description

March 5, 1957 v. cmmpoum 2,783,497

APPARATUS FOR HEAT TREATING LATEX ARTICLES Filed Dec. 1, 1955 7 Sheets-Sheet 1 FIG.I

Ki an; /a

F l G l 6 INVENTOR VALERIO CIAMPOL|NI BY A A'TTJSM March 5, 1957 v. CIAMPOLINI 2,783,497

APPARATUS FOR HEAT TREATING LATEX ARTICLES Filed Dec. 1, 1953 '7 Sheets-Sheet 2 FIG.

- INVENTOR VALERIO CIAMPOLINI j ihoc, 7 M

ATTORNEYS.

March 5, 1957 v. ClAMPOLlNI 2,783,497

APPARATUS FOR HEAT TREATING LATEX ARTICLES Filed Dec. 1, 1953 7 Sheets-Sheet 3 i Efiio u 1 l I E w q i; 3 m 2 0 1 1 I I i V N INVENTOR '4 VALERIO CIAMPOLINI,

ATTORNEYS.

March 5, 1957 v. CIAMPOLINI APPARATUS FOR HEAT TREATING LATEX ARTICLES Filed Dec. 1, 1953 '7 Sheets-Sheet 4 7 M ATTORNEY S.

March 5, 1957 v. CIAMPOLINI APPARATUS FOR HEAT TREATING LATEX mmcuss Filed Dec. 1, 1953 7 Sheets-Sheet 5 March 5, 1957 Filed Dec. 1, 1953 FIG. 8

v. CIAMPOLINI 2,783,497

APPARATUS FOR HEAT TREATING LATEX ARTICLES 7 Sheets-Sheet 6 NIP;

INVENTOR VALERIO CIAMPOLINI March 5, 1957 v. CIAMPOLINI 2,783,497

APPARATUS FOR HEAT TREATING LATEX ARTICLES Filed Dec. 1, 1953 7 Sheets-Sheet 7 FIG.

FIG. IO

FIG. 9

a INVENTOR.

VALERIO CIAMPOLINI United States Patent" 2,783,497 APPARATUS FOR HEAT TREATING LATEX ARTICLES Valerio Ciampolini, Milan, Italy, assignor to Pirelli Saps'a This invention relates to a method and: apparatusjor heat treating articles of latex, that is, of latex (or latexfoam) of natural rubber, synthetic rubber, or plastic materials, to solidify and/ or vulcanize the same. More specifically, the invention relates to a method and apparatus for carrying out such heat treatment by means of fluent steam applied directly to the article in a sealed heat-treating zone under very low pressure e. g., a few thousandths of an atmosphere, with the steam being admitted to the heat treating zone cyclically in response to condensation of steam therein.

The principal advantages obtained from my improved method and apparatus are a remarkable saving in steam and a reduction in the time required to heat-treat the am ticles to be solidified and/ or vulcanized, owing in part to precluding the mixture of air with the steam during the heat treating process. Other advantages of my invention appear from the description of the preferred form of apparatus for performing my improved process, as set forth hereinbelow.

Broadly comprehended, this apparatus consists of three principal parts, viz:

(1) A platform supporting the articles to be heat-treated, and having inclined planes to facilitate the discharge of the steam air condensate into a gutter trough, attached to the periphery of said platform;

(2) A light metal hood, fitting over'said platform, and pivotally mounted, so that it can be raised by rotating it about said pivots, to allow charging and discharging 0fually operated by-pass valve for the starting operation,

and a main valve, operated automatically by the raising and lowering of the hood, in accordance with the steam pressure therein.

The steam is fed into the closed hood through a specially arranged manifold located near the top of the hood and parallel to its longer side, at a very slow rate, so as to gradually displace the air in said hood, without forming a mixture therewith. The air thus displaced bubbles out through the water in the aforesaid trough, and when said air bubbles no longer appear (as indicated by steam bubbles), heat treatment can be started by closing the by-pass valve, whereupon the steam in the hood con-.

denses, causing the hood to descend to its closed-position,

with its lower edge forming a water-seal with the water in said trough. As the hood approaches its lowermost position, it automatically contacts a push button on the aforesaid main valve, which thereupon opens and allows steam to enter the hood and act thereon in an opening I direction. The balancing of forces acting on the hood brings it to a stable position which maintains a constant temperature therein, until the heat treatmentis over; whereupon the by-pass valve is opened for a few seconds,

2,783,497 I Patented Mar. 5,195?

permitting the entrance of steam into the hood which raises it from engagement with the aforesaid water trough, after which the hood is further raised to full open position by hand.

With the foregoing and other objects in view which may be incident to my improvements, my invention consists of the combination and arrangements of steps and elements hereinafter described and illustrated in the accompanying drawings, in which the same reference -characters denote the same parts in the several figures, and in which:

Fig. l is a side elevation of the apparatus, with the hood in closed position;

Fig. 2 is a front elevation of the apparatus, with th hood in closed position;

Fig. 3 is the same as Fig. 2, but with the hood in open position;

Fig. 4 is a plan view of the same apparatus shown in Figs. 1, 2 and 3;

Fig. 5-A is a central, longitudinal section, on an enlarged scale, of the steam-distributing manifold, and Fig.

5,-B is a cross-section of the same, ona still further enlarged scale;

Fig. 6 is a side elevation (partly in section), on an en-v larged scale, of the main steam regulating valve;

Fig. 7 is a section (on an enlarged scale) along the line 7-7 of Fig. 4;

Fig. 8 is a schematic view of the installation for auto matic operation of the apparatus shown in Figs. l-7;-

Fig. 9 is a small scale schematic view of the automatic regulating portion of the installation shown in Fig. 8,

during the starting phase of its operation;

Fig. 10 is the same as Fig. 9, during the working phaseof operation; and

Fig. 11 is the same as Fig. 9, during the sprinkling,

phase at the end of the heat treatment operation.

Referring first to Figs. 1-4, the reference numeral ,1

denotes a sheet metal platform for holding the articles or material to be' heat-treated, supported by a base 2,

comprising iron columns 3, connected by channel bars,

4, electrically welded together to form a unitarystructure.

Platform 1 is formed with inclined planes 5, sloping from its center to its periphery (see Figs. 3 and 8), to which is attached a U-shaped metal gutter trough 6 (see Figs. --3': and 7-). The slopes 5 of platform 1 facilitate the dis;

charge of steam/water condensate falling thereon, into the adjoining trough 6. A pipe 7 conducts steam, under a very low pressure (e. g. a few thousandths of an atmosphere), from a source (not shown) to a main flow regulating valve 8, which is connected by a pipe 9 to a, steam i distributing manifold 10, as furtherdescribed hereinbelow, Pipes 7 and 9 are also connected by a pipe 11 which by:

passes valve 8, and through which the flow of steam into manifold 16 is controlled by a manually operated by-pass valve 12.

Fitting over platfoim 1 is a movable hood 13 of light, corrugated, sheet metal (preferably aluminum), ha"ving integral top and side walls, shaped as shown in Figs. '1, -2 and 4, and provided with reinforcing ribs 13a, as shown;

in Fig. 1.. Hood 13 is made as light in weight as practicable, in order to reduce the mass of metal to be-heated during each cycle of operation, and also toavoid the use' or superfluous metal, taking into account the very low working pressure (e. g. /3 grams per square centimeter);

of the steam inside said hood. Attached to the four side walls of hood 13 is a tubular metal frame-14, which mantle raised fromi-itslhorizontal (closed) position (Figs.

lifiltdtzi Whereihedowen-edges of its=sidewalls dip into As shown in Fig. 6, the main steam regulating valve 8 is of the poppet type, comprising a conical seat I? (preferably of stainless steel) which is engaged by a conical valve head 20, biased toward closed position by a spring 21. A push button 22, slidably mounted in a bracket 23 on the top of valve 8, is adapted torengage the upper end ofxa stem.24.of.valve 20, so as to open said valve when said button is pushed downwardly, as hereinafter further described. When valve 3 is closed, steam can be admitted through by-pass pipe 11 and pipe 9 to manifold 16, by manually opening by-pass valve12.

.Asshown in Figs. -A and 5-13, steam distributing manifold 10 comprises a pair of horizontal, telescoped pipe and 26, of which the smaller and inner pipe 25 has .on its bottom a series of perforations 27, spaced at increasing distances from its entrance end (connected to pipe 9). Perforations 27 are so positioned in order to obtain an even discharge of the steam throughout the length ofthe pipe 25. Were the perforations equally spaced, the steam would. be discharged in greater quantity adjacent the downstream end of the pipe. Pipe 25 is supported at its left end by connecting pipe 9 and at its right end by a tubular support 28 (see Fig. 3). Pipe 26 is clamped to pipe25 .by anadjustable clamp 29 which, with spacers 30, holds said pipes in desired spaced relation to each-other, as shown in Figs. 5-A and 5-B. Along the whole top of pipe 26 is'a'narrow slot 31 through which steam, discharged into pipe 26 through holes 27, escapes into hood 13.

Thefunction of manifold 10 is to admit steam intohood 13,- at a very low rate (which is controlledby the size and spacing of holes'27), simultaneously throughout the length of said hood (by means of slot31); and since manifold 10 is located near the top of said hood (Fig. 1), the dischargedsteam first accumulates in the top of the hood,'displacing the ail-therein. As the discharge of Manual operation Before operation of the above describedapparatus commences, trough 6 is fil'ledwith water, the level of which is thereafter automatically maintained by steam/ water condensate draining from platform 1. After the articles or materials to'be heat-treated are placed in position on platform 1, hood 13 is lowered to its horizontal (closed) position,-; and steam isadmitted thereto throughmanifold 10, by manually opening by-pass valve 12. The steam issiling'at a low speedthrough slot 31 inma-nifold 10 gradually 'fills hood 13".and' displaces the air-therein progressively from the top to the bottomofsaid hood. The expelled escapes in the formof bubbles from the water in t'rough 6,;andas soon as'these air bubbles are followed by -st'eam bubbles, said-steam indicates to. the Eoperator that-the worldngphase of the apparatus may begin..

The starting (warming up) phase may last from 30-40 seconds-tofrom-A-S minu-tendepending upon theamount of material to be heated (i. e. greater weights of material require longer times). At the end of the starting phase, by-pass valve 12 is closed, whereupon the steam in hood 13 condenses to platen-and since no outside aircan-renter hood 13, because of the water seal between the lower edge ofsaid-hood and trough ,6, a slight vacuum is produced inside the hood. This vacuum causes hood 13 to descend slightly, whicnimovement brings a rod 32, attached to frame 14, in contact with push bottom 22 (as shown in Figs. 1 and 2), and; slightly opens valve8, whereupon the resulting new influx of steam into hood 13 raisessaid hoodandcloses-valve 8. These small up and down movements of hood-13 may take place without becoming apparent, and the hood rapidly assumes a balanced position, corresponding to an-equilibrium between the rate at which the steam in hood 13 condenses (in consequence of thermal losses), and the rate of admission of steam through valve 3.

The heat treatment proceedsfor a sufficient length of time to achieve its object (e. g. solidify liquid latex to desired-consistency, or to vulcanize raw rubber to desired degree); whereupon the process is stopped, by manually opening'by-pass 12 which admits sufficient steam to lift hood 13 soas to break its water seal in trough 6, and then lifting saidhood to its vertical position by hand.

After. the disengagement of hood 13 to its vertical position, the-residual steam in the hood is dispersed and condensed by spraying it with finely atomized water, which is introduced into hood 13 by a plurality of spray nozzles 33, supplied with water by a pipe 34 from a source (not shown), (see Fig. 3). This spraying operation may require-froml to 4 minutes (according to the load of material on platform 1), when using a flow of atomized water of 1'5-20 litersper minute,-for-the nearly totalelimination of 'theresidual steam.

Automatic Operation Theoperationtof the above described apparatus may be made automatic by employing a cycle-regulating device,.;having,.a plurality of pneumatically operated control valves, 35and 36 (Fig. 8) for the-remote control of the admission of.-steam into hood 13 during the first (starting) -phase,. the flow of atomized water during .the third- (spraying) phase, and the positioning of hood 13 during .said spraying phase.

Valvesx-35 land 36 "are supplied with compressed air by a pipe 37,-having. a. pressurecontrol valve 38. and connected to a source of compressed air (not shown). Valve. 35 :isconnected by a pipe 39 to a diaphragm 40 ofa valve-actuator. 41, having a stem-42 attached to diaphragm 40,- and-a spring 43 which opposes the upward movement of-said diaphragm. Stern 42 is adapted to contact'theleft end '44 of awalking beam 45, pivoted at 46,-and having itsright end 47 adapted to contact push button 22 attached to main regulating valve 8, as shown in Figs. 8-:11. Whenair is admitted by valve 35'to diaphragm .40, the. latter. raises stem 42 which then engages 'the left end 46 of beam 45, causing its right end 47 to depress button 22 and open valve 8, whereupon the direct admissionof steam into hood 13 ceases, wh ereupon-the condensation of steam in hood 13 lowers said hood to its horizontal (water-sealed) position, as shown infFig. 10. "The lowering of hood 13 brings rod 32 into contact with end 47 of beam 45 and push button 22, thus subjecting the operation of valve 8 to the oscillating movement of hood 13 (Fig. thus beginning the phase of self-regulated heat treatment, as described hereinabove, under Manual operation.

The duration of the period of heat treatment is predetermined by the object of said treatment, and upon its termination, pneumatic valve 35 opens, causing an instantaneous opening of valve 8, which disengages the hood 13 from its water-seal in trough 6. Nearly at the same time, valve 36 is opened, admitting compressed air through pipes 48 and 49 to cylinder 50, where it de presses piston 51 which (through connecting rod 52) lowers the free end of frame 14, and raises hood 13 until it disengages with the water in trough 6. At the same time, the opening of valve 36 admits compressed air, through pipe 48, to a diaphragm 53, which (against opposing spring 54) raises a stem 55 attached to a valve 56, thereby opening said valve and admitting cooling water, from a source (not shown), through pipes 57 and 58 and spray nozzle 59 to hood 13. (See Fig. 11.)

Since the cooling water must enter hood'13 some seconds after piston 51 has lifted said hood from engagement with the water in trough 6, the necessary delay is obtained by providing a small drain hole 60, in the lowest part of pipe 58, whereby said pipe is automatically emptied of water whenever valve 56 closes, and the time required for water to fill pipe 58, after passing valve 60 and before reaching spray nozzle 59, supplies said delay. If the time required to fill pipe 59 after opening valve 56 does not provide sufiicient delay for the water entering hood 13, said delay time can be readily increased by interposing in line 58 a small accumulator tank, whose volumetric capacity is such that the time required to fill said tank equals said increased delay time. The area of drain hole 60 is so small that the loss of water escaping therethrough, during the spray phase, is immaterial. Alternatively, the necessary time delay, between the disengagement of hood 13 with thewater in trough 6 and the entrance of water into said hood, can be obtained by the use of a third pneumatic valve (not shown), arranged in parallel with valve 3 6, and through which compressed air may be admitted tooperate valve 56, independent of the admission of air to cylinder 50 by valve 36, whereby the time interval between the operation of piston 51 and the opening of valve 56 may be adjusted as desired. 1

At the end of the spraying (cooling) phase,pneumatic valve 36 closes valve 56, whereupon hood 13 is raised manually to its vertical position. v

The succession of operations described above is controlled automatically by pneumatic valves 35 and 36, which are electrically actuated upon the closing of a switch 61 (Fig. 8), after hood 13 is first lowered to its horizontal position, at the commencement of a cycle of operations.

It will be understood that some adjustments in the operation of the above-described apparatus will be required depending chiefly upon the object of the heat treatment in each case. Thus, the timing of the various phases of the process will be different when the apparatus is used to solidify liquid latex of plastic materials, than when said apparatus is used for vulcanizing articles obtained from latex or latex-foam of natural or synthetic rubber. It will be further understood that the above described apparatus can also be used, in some cases, to vulcanize articles of natural or synthetic rubber obtained from compounds which vulcanize at a temperature of about 100 C. (i. e. the temperature of steam at substantially atmospheric pressure).

While I have shown and described the preferred embodiments of my invention, I desire it to be understood that I do not limit myself to the precise details of the process and apparatus disclosed by way of illustration,

as these can be changed and modified by those-skilled in the art without departingfrom the spirit of my invention nor exceeding the scope of the appended claims.

I claim:

1. In an apparatus for heat treating latex with fluent steam substantially at atmospheric pressure, the com bination of an hermetically sealed heat treating chamber of definite initial volume, said chamber comprising a platform for supporting the material to be heat treated, and a movable hood disposed above said platform and material and hermetically sealed to said platform by an hydraulic seal; supply means for supplying steam to said chamber; and means operatively associated with said supply means and responsive to the movement of said hood for automatically regulating the supply of steam to said chamber in accordance with the condensation of steam in said chamber, whereby'a thermal equilibrium and a predetermined constant temperature are maintained insaid chamber during the period of heat treatment.

2. In an apparatus of the type described, the combi-' nation of a platform sloping outwardly and downwardly towards its peripheral edge, said edge being provided with a trough extending continuously therealong and adapted to receive steam/water condensate draining from said platform, a movable hood disposed above said platform and including dependent sidewall means engageable in said trough as said hood is downwardly moved, said platform and hood comprising an hermetically sealed chamber when said sidewall means is engaged in liquid condensate in said trough, means for supplying steam to such hermetically sealed chamber, and means responsive to movement of said hood relative to said platform for regulating such supply of steam;

3. Apparatus according to claim 2, wherein said hood is pivotally mounted above said platform so that, by pivotal motion on its mounting, said hood may be raised from a horizontal position, wherein it forms a hydraulic seal with the liquid in said trough, to a vertical position, wherein it completely uncovers said platform.

4. Apparatus according to claim 3, having means for discharging the steam admitted to said chamber near the top of said chamber so that said steam displaces the air in said chamber progressively downward from said top, and said air escapes from chamber through the liquid in said trough, whereby the mixing of said steam and air is avoided. Y r

5. Apparatus according to claim 4, wherein said steam discharging means comprises a distributing manifold consisting of a pair'of spaced concentrically disposed tubes, the innermost one of said tubes being provided with a series of holes along its lower part spaced at increasing distances from the entrance of said manifold, and the outermost one of said tubes being provided with a narrow longitudinal slit, extending throughout substantially and outer tubes, to said platform below said manifold."

7. Apparatus according to claim 3, having remote-controlled means for automatically starting and stopping the admission of steam to said chamber, for starting and stopping the admission of cooling water to said chamber,

and for raising and lowering said hood with reference to said platform.

8. In a heat treating apparatus of the type described,

the combination of a platform provided with a peripherally arranged trough adapted to receive liquid from the platform, a movable hood disposed above said platform, the dependent sidewalls of said hood being disposed for engagement with liquid in said trough to form a seal between said-trough and'platform, a steam disharge manifo d-disposed with n :seidho di a str amli e tedit sa d man fold; allow-e r aos d in .sa sli team: lin nd pr vide w t ,s. valve to one position, and means associated w hnsaid ee and pe e y as oc ated -;w haid a e o imparting actuating movement to said valve-in response to movement of said hood relative; to said platform, whereby admission of steam to saidgh'ood is regulated in accordance with condensation ofsteamwithin saidhood.

9. In-a heat treating apparatus of thetype described, thecombinationof a platform provided with a peripheral trough disposed to receiveliquid from said platform; a hood; means-mounting said hood above said platform for movement toward and away fromsaid platform, said hood being biased towards saidpla-tform with. its depending sidewalls disposed for engagement withliquid in said trough, said hood .andvplatform constituting a sealed chamber when saidsidewal-ls are so engagedysup- P Y mean r a mi ting steam to said hoodrfi w' on r l means operatively associated with said supply means; u omati m ans in erc nnecting sai hoo an i f flow cont o mean f r ctua ing th lat er. solely; in accor asewith m emen s of sai hood rela ive o. said. P orm, and. m an pera ivelv-connec ed with, said; :flow ontr l me s fo a tuat ng the same; in pe dently. o said automatic actuating means for supply of, steam to said hood regardless of the relative positions of saidhood and platform,

10-11 21 he t treat ng appar tus .ofthe-type. described, the combination of a platformprovided ,witha peripheral trough disposed to receive liquid fromsaid platform; a hoodymeans mounting said;-,hood ,above, said platform for movement toward and awayfromsaid platform,said hood being biased towards said-platform with its depending sidewalls disposedfor engagement with liquid in said trough, said hood and platform constituting a sealed chamber when said sidewalls are so engaged; supply means f0; admittingsteam to said hoodrfiow control.

means operatively associatedwith said supply means;

automatic means interconnecting said hood. and saidfiow control. means for actuating the, latter. solely in accordance with movements of saidhood relative to said plat form; spray means for applying cooling liquid-tosaid hood to dissipate the steam thereingpower, means operatively connected with Sflid hQOd and constructed to raise the same out of its operative ,positiomimeans for actuating said power to raise said hood, and meansactuated upon occurrence of such operation of said'power means for supplying cooling liquid tosaid pray means.

11. In an apparatus forheat treating latex articles with fluent steam, the combination of upper and lower members cooperating to defineaheat treating chamber, means mounting one of said members for movement toward and away from the otherof said members between an operative positionin which said members are adjacent to each other and a second'operative position in which said members are spaced apart, sea-l means cooperating with both of said members to form afiuid seal therebetween, said seal means operatively engaging bothof; said members in sealing relationship throughout movement of said one member between said operative positions, whereby said chamber is maintained hermeticallysealedduring such movement, said one member being biased toward said other member, supply means for. supplying steam to said chamber, and means operatiyely associated with said supply means and responsive to the movementof said one member between said operatiyepositionsfor automatically regulating the supply of steam to saidchamber in accordance with the condensation of stearn in said chambenwhereby a thermal equilibrium and :a predetermined constant temperature are maintained in said chamber-x during the period of heat treatment. 3

12. In an apparatusfor heattreating l atexarticles for" nation of a base, a hood disposed abovesaid base and oper tin there th o e er ne rn e heat treating-space, means mounting said hood for movement toward and away from said base between a first operative position in which said hood is disposed immediately adjacent said-base and a second operative position in which said hood is spaced from said base, seal means cooperating with said base and hood to form a fluid seal therebetween, said seal means operatively engaging both said base and said hood in sealing relation throughout movement of said hood between said operative positions, whereby said enclosed space is maintained hermetically, sealed as the volume thereof is varied by movement of said hood, said hood being biased toward said base, supply means ar- 'ranged to admit steam to said enclosed space, control means for regulating the admission of steam by said supply means, and means operatively associated with said control means and responsive to a predetermined movement of said hood and thus to occurrence of a predeteri;mined change in volume of said enclosed space, for actuating said control means to regulate the admission of steam to said enclosed space by said supply means.

13. An apparatus constructed in accordance with claim 12 and in which the means mounting said hood for move ment relative to said base includes a counterbalance so constructed and arranged that increasing steam pressure within said chamber is effective to cause movement of the hood away from the base and decreasing steam pressure within said space is efiective to allow movement of the hood toward said base under the biasing action of gravity.

'14. In an apparatus for heat treating latex articles for a predetermined period by contact with steam at a substantially constant temperature and pressure, the combination of a heat treating chamber comprising two members cooperating to define an enclosed space and seal means cooperating with both of said members to maintain said space hermetically sealed, mounting means sup porting one of said members for movement between an inactive position removed from the other of said members, such that articles to be treated may be inserted in said chamber, and a position adjacent said other member, said mountingmeans allowing relatively free movement of said one member toward and away from said other member throughout a range of operative positions adjacent said other member, said seal means operatively engaging both of said members in sealing relation throughout said range of operative positions, whereby said space is maintained hermetically sealed as the volume thereof is varied by movement of said one member, said one member being biased toward said other member when occupying said operative positions, supply means arranged to admit steam to said enclosed space, control means for regulating the admission of steam by said supply means, and means operativcly associated with said control means and responsive to a predetermined movement of said one member in said range ofoperative positions, and thus to occurrence, of a predetermined change in volume of said enclosed space, for actuating said control means to regulate the admission of steam to said enclosed space by said supply means.

References Cited in the file of this patent UNITED STATES PATENTS 734,489 Wittenberg et a1 July 21, 1903 1,125,609 Warner Jan. 19, 1915 1,557,093 Roesch Oct. 13, 1925 1,662,804 Dressler Mar. 13, 1928 1,829,018 Schade Oct. 27, 1931 2,329,467 Glynn Sept. 14, 1943 2,428,944 Schrank Oct. 14, 1947 2,505,826- Dibdin ..May 2, 1950 2,526,461 Dibdin Oct. 17, 1950 4amnn-a...

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