US2830325A - Mold for forming open-ended bulbs - Google Patents

Description

April 15, 1958 c. s. BRAY MOLD FOR FORMING OPEN-ENDED- BULBS Filed May 10, 1956 nvmvrox Jay.

United States Patent 9 t ice 2,830,325 I MOLD FOR FORMING OPEN-ENDED BULBS Calvin S. Bray, Saylesville, R. I., assignor to Dave] Rubber Company, a corporation of Rhode Island Application May 10, 1956, Serial No. 583,955

Claims. (Cl. 18-39) The present invention relates generally to the manufacture of plastic and rubber articles, and more specifically represents a modification of certain structure disclosed in my co-pending application, Serial No. 526,228,- filed August 3, 1955, and entitled Manufacture of inflating Bulbs.

A primary object of the instant invention is the provision of a mold particularly adapted to the manufacture of large neck inflating bulbs, such'as syringe, aspirator, and evacuation bulbs.

. Another object of the instant invention is the provision of a mold which will form such an inflating bulb complete with neck passage in one operation.

Another object is the provision of a mold of the character described having novel and improved pin means therein for providing the desired neck passage in the bulb and for simultaneously insuring that, the bulb neck will be relatively thick and built up.

A further-object of the instant invention is the-provision of a mold particularly adaptable to the manufacture of relatively large bulbs of the character described.

Other objects, features and advantages of the invention will become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings. I

p In the drawings which illustrate the best mode presently contemplated by me for carrying out my invention:

Fig. 1 is an elevation in section of a mold embodying the instant invention in separated relation;

Fig. 2 shows the mold of Fig. 1 in operative position with the bulb formed therein;

Fig. 3 is a sectional elevation of a bulb formed in accordance with the instant invention after removal from the mold;

Fig. 4 is a sectional elevation of the bulb of Fig.3 after the resilient closure has been broken away;

Fig. 5 is a perspective detail of a bulb made in ance with the instant invention; 1

Fig. 6 is a perspective detail of the pin element which forms a part of the instant invention; and

Fig. 7 is a perspective detail of a collar element that forms a part of the instant invention.

As described in detail in my co-pending application, Serial No. 526,228, filed August 3, 1955, there has been provided a way to mold resilient bulbs of the type used in connection with syringes and the like in a single operation. More specifically, the mold comprises an upper bulb section It) and a cooperating lower bulb section 12. Section 10 is pivotally mounted as at 14 to an outwardly extending arm 16 which extends from a central hub, not shown. It will be understood that a plurality of the radially extending arms 16 may be provided for establishing a rotary mold of the gang type. In view of the fact that this structure forms no part of: the instant invention, however, no detailed description thereof is deemed necessary. It will be noted that the upper bulb section 10 is provided with a peripheral head 18 at-its lowermost edge, and on the in accord- 2,830,325 Patented Apr. 15, 1958 terior of said-lowermost edge there is provided an annular recess 20.

The lower bulb section 12 is provided with a threaded bore 22 at its lower extremity for receiving a screw 24 which mounts said lower section to a plate or support 26. The upper edge of section 12 is providedwith an annular upper rim 28 having a flat portion 30 and an.

upwardly inclined portion 32 which cooperate .with the peripheral bead 18 to form a snug enclosure when the' sections are brought together, all in a manner clearly illus-- trated in Fig. 2. 7 Lower section 12 also carries an annular recess 34 which cooperates with the aforementioned recess 20 to provide an annularinternal groove in'the assembled or closed mold. 7

mold. Thus when the mold sections are in the position of Fig. 1, it is only necessary to swing the upper mold section slightly away from the lower section whereby the proper amount of moldable liquid may be poured into the latter. It has been found that a plastic material known'to the trade as Plastisol, which material actually is polyvinylchloride, has proven to be particularly adaptable to this molding operation although it will be. understood that any other material in liquid-form which can be cured into a flexible hollow form, such as latex in solution, may be utilized if desired. After the proper amount of moldable'liquid has been poured into the, lower mold, the mold sections are locked together and are rotated in a curing oven in a manner well known in the art.

Since the instant invention is adapted to the one operation molding of singleor double-necked bulbs of the i type disclosed, an internally extending pin element 36 is carried by the lower bulb section 12. It will'be understood, however, that the same pin structure could be utilized on the upper mold section also should it be desirable to form a double-necked bulb. The pin 36 com-.

prises an externallythreaded head 38 which is adapted to be threadedly received by the bore 22. Pin 36 further comprises an elongated shank portion 40 and a shoulder portion 42, the outer diameter of which determines the size of the passage to be formed in the'bulb neck. As

described in my aforementioned co-pending application,

the bulb assumes the appearance of Fig. 4. As illustrated therein, any burrs or irregularities such as shown at 46 will be. disposed interiorly of the completed bulb and will not be visible.

In the manufacture of inflating bulbs of the type de- I scribed, it is desirable that the completed bulb have an enlarged or built-up neck portion surrounding the passage aperture 50. It is also important that the covering 44 be relatively thin so that it may easily be broken away from the completed bulb 43. And in addition to these features, it is, of course, necessary that the bulb itself be of the desired thickness. When making relatively small bulbs, the aforementioned factors do not present a very serious problem. However, when relatively large bulbs are being molded in the aforedescribed manner, a very real and serious problem exists with respect to the factors just enumerated. Therefore, in accordance with the instant invention, means are provided for overcoming these problems, and thus it follows that my inventionis of particular value in connection with the melding of relatively large bulbs.

Since it has been found that the thickness or amount of build-up of polyvinylchloride which results during the aforedescribed molding operation is directly proportional to the heat applied at any given location, I have found it desira-ble'to provide a pin 36, the shank portion of which is of a material having a relatively low coefficient of-heat conductivity, while the shoulder portion thereof is of amaterial having a relatively highcoefiicient ofheat conductivity. The mold sections 10' and 12 are preferably constructed of a material, the heat conductivity of which is less than that of said shoulder portion but greater than that of said shank portion. Thus I construct the pin 36 of a plastic material, preferably that which is known to the trade as Tefion" and-which chemically is known as polytetrafluoroethylene. I find thatsatisfactory results can be obtained, however, by'making the pin-36 of a plastic known to the trade as Kel-f, which chemically is trifluorochloroethylene. Since those plastics are characterized by a relatively low coeflicient of heat conductivity,it will follow that the covering 44 whichforms thereon will berelatively thin, and hence said covering may be easily broken away from the completed bulb in the manner' aforedescirbed.

Since it is desired to provide a-thick and built-up neck section, however, such as shown at 52-, I make the shoulder portion 42 of the pin 36 of a material characterizedby a high coefficient of heat conductivity. Thus the shoulder 42 may actually comprise a separate element, such as a.copper collar which is a press fit over enlarged por-- tion 54'of"shank 40and abuts against head38'. In some instances, it may be desirable to actually pinor stake the collar 42 in position, as shown at 43. *Sincethe shoulder or collar 42 is highly heat conductive, it will follow that a relatively large degree of heat, will accumulate in the-area of the mold where the neck portion is to be formed, thus insuring that a solid 'neckportion, such as shown at 52, will result. The mold sections themselves arepreferably constructed of aluminumwhereby to resultin the provision of a completed bulb having a thickness somewhere in between the thickness of the covering 44 and the neck portion 52. Y v

Thus it will be seen that the instant inventionpresents a modificationwhich enables my original invention as disclosed inmyafore-referred-to ;co-pending application to" be successfully utilized in-connection-with themanufacture-of relatively large bulbs. The basic concept of the inventionis' the provision ofan internally extending pin, the shank portion of which'isof amaterial having a'relatively low coefiicient of heat conductivity while theshoulder portion thereof is highly heat conductive;

Without my invention; it has been fou-nd that relatively large bulbs are formed with an inwardly extending. sleeve or hub at the passage rather than the desired solid neck portion shown at 52'. Not only does this'result -in an article which-is not as elfective or durable inuse, but it also poses a problem when tearing away the resilient covering 44 since there is a tendency for the entire sleeve or hub to rip off.

While there is shown and described herein certain specific structure embodying the invention, it will be manitest to those skilled in the art that various modifications and rearrangements of the parts may be made without departing from the spirit and scope of the underlying inventive concept and that the same is not limited to the particular forms herein shown and described except insofar as indicated by the scope of the appended claims.

I claim:

1. A mold for use in the manufacture of hollow re silient bulbs having a neck portion with a passage extending therethrough, said mold having a lower bulb section, an upper cooperating bulb section separably mounted thereon, and a pin element extending inwardly from one of said sections, the portion of said pin adjacent to the section'from which it extends being of a morehighly heat conductive material than that of said sections.

2 A mold for use in the manufactureof hollow re silientbulbs having a neck portion with a passage extending therethrough, said mold having a lower bulb section, an upper-'cooperating bulb scctionseparably mounted thereon, and apin element extending inwardly from one-of said sections; the portion of saidpin most closely adjacent to the section from which it extends being more highly heat conductive than said sections, while the remaindcrofsaid"pinis'of a material characterized by alesser degree of h' e'at conductivity thansaid shell.

3.A- mold for use in the manufacture of hollowresilient bulbs havinga-neck portion witha passage extending therethrough;'said mold having a lower bulb section, an upper'coopera-tingbulb section separably mounted thereon, and a pin element extending inwardly from one of said sections; said pin having a shoulder portion adjacent the section from which the pin extends, and a relatively thin shank portion extending inwardly therefrom,

References Cited in 'thefile of this patent UNITED STATES PATENTS 2,469,892 Rempel MaylO, 1949 2,588,571 Porter Mar. 11, 1952 2,624,072 Delacoste et al. Jan. 6, 1953 2,730,765 Crafton et a1. a Jan. 17, 1956

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