US2463562A - Method and apparatus for making hollow rubber articles - Google Patents

Description

March 8, 1949.

Filed July 10, 1945 F. T. ROBERTS ET AL METHOD AND APPARATUS FOR MAKING HOLLOW RUBBER ARTICLES 3 Sheets-Sheet 1 FIG. 2

JNVENTORS.

JF' @wJ r March 8, 1949. F. T. ROBERTS ETAL 2,453,562

METHOD AND APPARATUS FOR MAKING HQLLQW RUBBER ARTICLES Filed July 10, 1945 3 Sheets-Sheet 2 25 2o v. ;:I" IIIIIII [N V EN TORS- March 8,.1949. F. T. ROB TS ETAL 2,463,562

MET D AND APP AT FOR MAKING OLLOW RUBBER TICLES Filed July 10, 1945 3 Sheets-Sheet S Patented Mar. 8, 1949 METHOD AND APPARATUS FOR MAKING HOLLOW RUBBER ARTICLES Fred Thomas Roberts and Robert Eldon Roberts, Ridgefleld, Conn.

Application July 10, 1945, Serial No. 604,204

21 Claims.

The object of this invention is to provide a method of forming balls and similar articles out of sheet rubber and effectively joining the seams thereof and to provide a simple apparatus which may be employed in carrying out such method. Briefly, in our method, we take a flat sheet of rubber vor similar material and buckle it inwardly in areas radiating from a center and bring together the material at opposite edges of such inwardly diverted portions to form'seams whereby the flat disc of material is converted into a cup-shaped member with seams extending in meridional directions, and it is a further object of this invention to provide for the ready deflection of the material in the regions to be discarded and for. bringing the remaining material together at the edges of such diverted portions to form the seams.

Our apparatus is shown in the accompanying drawings, and serves to illustrate also the method employed, and the description of the showing of such drawings further explains both the method and apparatus.

In the drawings, Fig. 1' is a plan of the apparatus, in position to receive a flat disc of rubber to be formed into cup-shape; Fig. 2 is a plan of a portion of such apparatus in its final position, which it occupies when the flat sheet has been converted into a cup; Fig. 3 is a vertical section v through the apparatus in sheet-receiving condition, this view showing the sheet resting by gravity on top of the apparatus, the plane of the sections being indicated by the line 33 on Fig. 1; Fig. 4 is a sectional side elevation of the apparatus in its final form, the section being in the plane indicated by the line 4-4 in Fig. 2; Fig. 5 is a detail in section through two adjacent supporting members of the forming apparatus after they have come together and pinched oi! the inwardly diverted portion of the rubber sheet, the location of this section being indicated for instance by the line 5---! on Fig. 4; Fig. 5a is a view similar to a portion of Fig. 5, showing a reinforcing strip covering the seam; Fig. 5B is a fragmentary sectional perspective of a V- shaped piece which may be inserted at the junction of the two article halves; Fig. 6 is a side elevation of an article as formed by the apparatus of Figs. 1 to 5; Fig. 7 is a vertical section through a two-part forming mold in which two of the articles of Fig. 6 are mounted and brought together to form a ball; Fig. 7a is a vertical section corresponding to part of Fig. 7, showing a valve plug on the interior of the article; Fig. 1B is a plan of a mold member having a number of cavities and passages, as shown individually in Fig. '7; Fig. 8 is a view of such completed ball.

Referring first to Figs. 1 to 5, Ill indicates a supporting standard which may be a vertical rod mounted on a suitable base not shown. At its upper end this rod carries several projecting wings l2 which are hinged to the rod. As shown the rod has a square head II, formed along its four sides with hinge ears l2, and we have shown four wings or "petals 20, the inner edges of which are curled into hinge ears 2!, suitable pintles 22 connecting the petals to the head of the standard. These petals are so formed that they are concavo-convex in both radial and transverse directions, and for making a spherical article they are for the most part sections of a sphere, so

that when lowered into cup shape their edges abut along meridional lines.

The apparatus shown in the drawings has four radiating petals and when that number is employed, and the apparatus is to form a hemisphere, each petal will comprise about a fourth of a hemisphere. Whatever the number of petals, or whatever shape of article is to 'be produced, the edges of the petals are so formed that when the petals swing down from the extended approximately horizontal position, indicated in Fig. 3, to closed position of Fig. 4, the edges of adjacent petals contact with each other and thus serve to pinch off any material depending into the spaces between them and f orm a seam in such material.

Preferably each of the petals is formed with an arcuate lip 24 at its lower edge beyond the spherical portion of the petal to produce an external annular rim on the cup-shaped article formed. This rim is of use in joining one cupshaped article to another to make a complete ball, as hereinafter explained.

Slidably mounted on the standard It is a slide 30 connected by links 3| with the interior .of the respective petals. As shown there are four of these links each pivoted to the upper end of the slide apart and each pivoted at its outer end to an ear 25 on the inner faceof the petal. When the slide 30 is in its elevated position, as shown in Fig. 3, the petals are all spread into substantially horizontal position ready to receive the sheet of material to be formed- In operation, a suitable disc of material is laid on such extended petals and being thin and flexible conforms to the upper surface thereof, as shown in the case of thesheet A in Fig. 3. Where such sheet bridges across'the space between the petals it tends to sag by gravity into such space.

3 However, to insure it remaining in the space as the petals are lowered, we provide a series of radial bars 40 which are adapted to overlie the sheet of material and pull it down into the space between the petals.

As shown, the four bars 40 extend inward radially tolformafringll. andare then bent upwardly approximately-as shown at 42. We have shown a support for the ring 4| comprising a second ring 45 connected by radial arms 46 to the main slide 30 and having an outwardly extending horizontal flange. The bar supporting ring 4| is shown as resting on the operating ring 45 and as latched thereto by latches 48 pressed inwardly by suitable springs 49.

In operation after the disc of material has been placed on the spread petals the ring 4| is mounted on the frame 45, thus causing the bars 40 to press the material downwardly in the region between the petals. Now as the slide 30 is lowered the petals are swung downwardly and the edges approach each other and at the same time the bars 40 carriedby the rings are moved downwardly so that the bars always keep ahead of the closing petals and in the final position the petals have sheared off the excess of rubber and formed meridional seams of a complete hemisphere, the bars holding the excess inwardly of such hemisphere, as shown in Fig. 4. As shown in Fig. 5, the petal edges are chamfered, so that they spread from the concave side, and thus force together the material across the edges, making an effective seam.

The apparatus and operation above described produces the article of Fig. 6 comprising the hemisphere B with a projecting rim C. Two of these hemispheres are now brought together with their rims abutting each other, and the rims are pressed together to form an equatorial seam and are then sheared off to make a complete article.

Fig. 7 illustrates suitable apparatus for forming such junction of the two hemispheres. As shown, this apparatus comprises a pair of mold members 50 each having a cavity in which the article B may seat. Each mold member is provided with a passageway 5| communicating at 52 with the article cavity and connected to a conduit 53 by which the cavity may be exhausted of air. Preferably also the mold has an annular groove 55 surrounding the cavity and connected with the passageway 5| by passageways 56.

,When the article of Fig. 6 is placed in the cavity of one of the mold members 50 and the air exhausted from the cavity beneath the article through the exhaust pipe 53, the rim C of the article is clamped by the suction to the groove 55 and the body of the article B is drawn down by suction against the wall of. the cavity.

When the articles have been thus seated in 'two mold members 50, such members are brought together' under pressure and the cutting edges 58 of the mold members between the main cavities and the surrounding grooves 55 pinch oil the excess of the rubber rim C and :by their inclined annular surfaces form an effective equatorial seam. After the separation of the mold members and the removal .of the article, the exterior of the equatorial seam is 'bufi'ed off, resulting in the formedarticle ready for vulcanizingin the presej'nt'rcase the'sphereD of Fig. 8. vulcanization may beefiectedby heat in a separate mold, or

the mold of, Fig. 7 may be employed with means to plug. the exhausting, openings .52 and an annularj reinforce surrounding the cutting edges, or, if

I desired, acid-curing may be used.

While we have shown a sphere as illustrative of the article to be produced by our method and apparatus, it is to be understood that the same operation, with an apparatus of correspondingly diflerent shape, may be employed for articles of other form, as for instance a spheroid suitable for a football bladder.

In the manufacture of football bladders and similar articles to be externally inflated, it is desirable to provide a self-closing valve plug on the interior of the article, such plug being adapted to have a hypodermic needle passed through it for inflation purposes, the plug sealing the opening when the needle is withdrawn. Such a plug is shown at E in Fig. 7a, the plug having a skirt e cemented to the interior of the rubber ball. When such a plug is to be employed we make a recess. indicated at Ila in the head H of the apparatus however, that the two mold members 50 may each have a number of cavities so that several of the cup-shaped members maybe formed at the same time. Such a construction is illustrated in Fig. 73 where 50a indicates a mold plate corresponding to the member 50 of Fig. 7, but having a number of cavities, the construction otherwise bearing the same reference numerals of Fig. 7.

It has been found that the present synthetic rubber is not as tacky, or self-adhering, as the regular natural rubber, and in most cases where 40 seams of this kind are made, when the synthetic rubber compound is used, it is desirable to strip or reinforce such seams with a thin piece of rub.

ber of the same synthetic rubber compound as used to make the article. Such strips of rubber may be a very thin piece of calendered rubber or a very small V-shaped piece, run on a tubing machine, which is pressed down into the V shown at the junction of the two pieces of rubber at the scam in Fig. 5. Such reinforcing strip is shown in cross section at A in Fig. 5a and the V-shaped strip is shown in cross section at A2 in Fig. 53. It is either cemented or cleaned with naptha and as it is on the outside of the ball and against the mold when cured it has been found that it does not show at all after the ball is finished and adds very little thickness to the same but does give strength.

The seam made from joining the two halves together is also strippedon the outside, the strip in this case being put over the equatorial V of the seam. As the compounding of the synthetic rubber progresses, it may more clearly resemble the natural rubber and be more easily seamed and then it may not be necessary or desirable to strip these seams, as they are all formed by chamfered edges of metal which are pressed together by hydraulic pressure.

It will be seen that our method and apparatus are comparatively simple. When the wings of the apparatus are extended it is merely necessary to lay a sheet of raw rubber or similar material on the apparatus, such sheet by gravity naturally sagging between the wings, and then to put the member carrying the bars in place with the bars extending over the sagging regions of the rubber 2,4os,sea

and then tolower the slide. This results in the unsupported portion of the material bein brought inwardly in radial puckers until the supported portions are joined by meridional seams into a cup-shape, the retaining bars moving downwardly ahead of the material and being thus on the interior of the cup produced.

The provision of an annular skirt on the cupshaped member produced enables two such cup- 1. The method of making cup-shaped members of plastic material having adhesive characteristics comprising supporting an approximately flat area of such material and causing substantially radial regions thereof to be diverted in- -wardly out of the general locus of the material and pinching the material together at the edges of the diverted regions to form seams.

2. The method of making a cup-shaped article of rubber or similar material from a substantially flat disc thereof comprising causing such disc to be diverted inwardly in substantially radial directions'while the disc is on a support having sep arated supporting members and then gradually moving said members until the edges thereof coact to shear ofl and join material which has been diverted.

3. The method of making cup-shaped articles comprising taking a sheet of rubber or similar material, supporting such sheet by movable members extending substantially radially from a cen. terwith radial flaring spaces between them, allowing the sheet to sag between the supporting members, lowering the supporting members with the sheet resting thereon by gravity and its own adhesion to cause the material depending between the members to become loops within the cup-shaped article which abut themselves adja cent the material on the supporting members, and pressing and shearing of! such material at the loops.

4. The method of making cup-shaped members of sheet material similar to rubber comprising supporting a sheet of such material on a support having radiating separated members so that the sheet may sag between the members. gradually swinging the members downwardly substantially about a center and at the same time pressing the sagging material between them downwardly and inwardly and bringing the supporting edges toward each other to shear oi! the said sagging material and form meridional seams thereat to form a cup-shaped member.

5. The method of making hollow articles comprising taking two sheets of rubber or similar material, placing each across a support having spaced members extending radially from a central region. whereby the rubber sheet may sag between the members, lowering said members to shear oi! the sagging portions and join the adjacent edges to make a cup-shaped member with a projecting rim, and thereafter placing two of such members together to form a junction at the projecting rims.

6. An apparatus for making cup-shaped articles of plastic sheet material comprising pivotally mounted convex wings adapted to carry a sheet of plastic material on their convex surfaces with 6 thesheet diverted between the wings, mechanism for swinging said wings to form the plastic material into cup-shape, the wings being so shaped thatthe edges oi adjacent wings operate to form a seam.

'I. An apparatus for making cup-shaped articles of plastic sheet material comprising an upright standard, radiating upwardly convex wings pivoted thereto and adapted to support a sheet of plastic material resting on the wings with the sheet sagging between the wings, mechanism for swinging said wings downwardly to form the plastic material into cup-shape external 01 the wings. the wings being so shaped that the edges or adjacent wings cooperate to form a meridional seam and pinch off the sag i material.

8. The combination of a suitable support, a series of radial wings pivotally carried thereby and eachcomprising a section of a sphere with its convex surface outward, means for supporting said wings extended whereby they may support a sheet of raw material resting thereon, and means for swinging said wings inwardly to form a junc-- tion of the material sagging between the wings.

9. In an apparatus for making cup-shaped articles of plastic material, the combination of the standard, a series of radial wings hinged thereto slide to the wings whereby they may be extended to form a support for an approximately flat sheet of material or be swung toward each other to cause their exterior to assume the cup-shaped form, the wings being so shaped that their edges come into abutting relation when they are swung into the cup-shape whereby the supported material may be joined to make a cup-shaped article.

10. The combination of a standard, a series of wings hinged thereto adapted to extend therefrom in different radial directions to form petals adapted to support a sheet of plastic material, mechanism for swinging the wings inwardly, and means for pressing inwardly the material between the wings as the edges of the wings approach each other, said edges being formed to coact and pinch the material between them.

11. An apparatus for making cup-shaped articles of sheet plastic material comprising a central standard, wings hinged tothe top of the standard and extending radially outward therefrom, the wings being so shaped that their edges may come together .as the wings are swung downwardly toward the central standard, means for so swinging the wings and means for drawing inwardly the material between the wings as the edges of the wings approach each other.

12. The combination of a central standard, a set of wings hinged to the top of the standard and extending outwardly therefrom in radial di-'- rections, means for swinging the wings inwardly along their pivots, aset of bars adapted to be placed over the material between the wings and means for lowering said bars as the wings are brought together.

13. An apparatus for making cup-shaped articles from sheet material comprising a standard, radial wings hinged to the top of the standard, each wing being arcuate in the radial direction and also transversely thereof, a slide on the standard, links connecting the slide with the wings, an annular support carried by the slide, a series of inwardly projecting bars carried by the annular support and adapted to overlie the material depending between the wings.

14. The method of making a hollow elastic ball comprising seatin'g sheet stock on the exterior of a convex forming member having an outward annular flange, such stock extending across the flange, thereafter bringing two of the formed sections together with the flange portions abutting and joining the same under pressure.

15. The method of making cup-shaped articles of plastic sheet material comprising placing such material about the exterior of a forming member, causing loops of the material to pass through spaces in the forming member, removing such internal material and pinching together the adjacent edges of the remaining material to form a seam.

16. The method of making a rubber article having panels joined by meridional seams, comprising placing sheet rubber on the exterior of a forming member, causing loops of such material to pass into the interior of the forming member through meridional slots therein, removing the excess of such material from the interior of the forming member, and pinching together the ad jacent edges of the panels to form meridional seams.

17. An apparatus for forming cup-shaped rubber articles comprising a forming member composed of spaced movable panels on the exterior of which a rubber sheet may be mounted, means for diverting the sheet through meridional spaces between the panels, and means for bringing the panels into edge coaction to pinch oif the internally projecting material and at the same time form meridional seams between the different panels of the remaining material.

18. In the method of making hollow articles of plastic sheet material, the steps comprising taking sheets of such material, bending the same and looping regions thereof out of the general locus of the material and pinching such loops together to form seams, thereby producing cupshaped members, while leaving outwardly projecting flanges at the annular edges of such members, whereby a single hollow enclosing member may be made by abutting and joining the flanges of two of such cup-shaped members.

19. The combination 01 a standard. a set of radial wings hinged to the standard adjacent the top thereof, each wing being curved in a radial direction and also transversely, each wing formed with a flaring portion adjacent its outer edge, means for swinging the wings inwardly on their pivots, whereby a sheet of material resting on the wings and sag ng between them may be converted into a cup-shaped member having a projecting rim. 1

20. An apparatus for making cup-shaped members comprising a standard, a set of radial wings hinged to the standard adjacent its top and adapted to extend outwardly like petals, each wing being substantially a section of a sphere with a flaring portion at the extreme end, a ring carrying inwardly projecting radial rods, means for supporting the ring and means for swinging the wings inwardly and for lowering the rods to maintain them on the interior of the wings.

21. An apparatus for making cup-shaped ar- REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 637,372 Cox Nov. 21, 1899 1,139,341 Cigol May 11, 1915 1,467,438 Lawton Sept. 11, 1923 2,370,827 Weichbrodt et a1. Mar. 6, 1945

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