US3145422A - Molding apparatus - Google Patents

Description

Aug. 25, 1964 c. J. DAUBENBERGER ETAL 3,145,422

' MOLDING APPARATUS v Filed June 28, 1961 INVENTOR.

3o CHARLES J.DAUBENBERGER F G 6 Armen/Em tion referred to in the art as ilash often results.

United States Patent 3,145,422 MOLDING APPARATUS Charles J. Daubenherger, Santa Monica, and Michael M. Neals, Venice, Calif., assignors to Daco Rubber, Inc., a corporation of California Filed June 2S, 1961, Ser. No. 120,232 1 Claim. (Cl. 18-39) This invention relates generally to molding apparatus and more particularly to an improved molding apparatus for forming insulating housings for electrical pin connections.

In many electrical connectors, multiple contact plugs are used. Generally, the plug structure comprises a plug body supporting a plurality of electrical pins for cooperation with a socket member including a similar body supporting a plurality of connecting or mating pins. The pins in each instance are individually held within holes in the bodies which both support and insulate the various pins. Wires, themselves are individually secured to the pins and extend from the rear of the plug and socket body.

An important part in the manufacturing of multiple connection plugs is the molding of the foregoing described insulated housings for supporting the electrical pin connectors. With apparatus employed heretofore, a condi- This flash constitutes minute pieces of rubber which tend to protrude into holes formed in the housing for receiving the pin connectors. Such small pieces of rubber or housing material not properly removed in the forming of the holes may result in an open circuit between connecting pins by insulating the same from each other. The presence of such flash is thus extremely undesirable and the formation of conductor housings without such flash would constitute a distinct step forward in the art.

With the above in mind, it is primary object of this invention to provide an improved molding apparatus in which housings for electrical pin connections can be formed Without any appreciable ash being present to the end that a greatly improved plug housing is available together With the more important advantages of complete reliability when employed for housing electrical pin connectors to be electrically connected together.

Briey, this object is realized by providing a molding apparatus including a pin and cooperating pin receiving tube structure in juxtaposed relationship to'deline each hole in a molded body to be formed. The head of the pin structure is itself partially telescopically received Within the upper opening of the tube. This upper opening has an internal prole such that after the material to form the housing has been confined so that the pin and tube define the hole passing through the vbody and the molding process completed, pulling away of the pin receiving tube from the pin results in part of the material within the tube itself removing any flash tending to form. The resulting product has a clear hole Without any flash present so that electrical connectors inserted therein will properly eliect a straight through conducting path.

A better understanding of the invention will be had by referring to the accompanying drawings illustrating one specific example of the improved molding apparatus of the invention, in which:

FIGURE l is a perspective View of one type of plug which may be formed by the molding apparatus of this invention;

FIGURE 2 is a greatly enlarged fragmentary cross section taken in the direction of the arrows 2-2 of FIG- URE 1;

FIGURES 3, 4, S, and 6 illustrate successive positions of the improved molding apparatus of this invention dur- 3,145,422 Patented Aug. 25, 19,64

CCl

ing the process of forming a plug housing such as illustrated in FIGURE 1;

FIGURE 7 is a greatly enlarged fragmentary cross section of one pin and pin receiving tube such as illustrated in FIGURE 5; and

FIGURE 8 is an enlarged fragmentary cross section of a portion of the structure of FIGURE 7 useful in explaining certain features of the invention.

Referring lirst to FIGURE 1, there is shown in perspective view a connector housing 10 provided with four openings 11 passing therethrough. Also provided on the housing 10 is an annular ridge 12 useful both for securing the material forming the housing within its mold during manufacture and also for later securement of the housing 10 Within suitable holding means. Ordinarily, the multiple connector type plugs capable of being manufactured by the improved molding apparatus of this invention include 0n the order of twenty-tive or thirty holes passing therethrough. The number of holes, however, depends on the application, and for the sake of simplicity only four such holes are shown. v

In assembling the plug, electrical connectors are secured Within the four openings 11, and a similar molded part is provided with mating electrical pin connectors.

Referring now to FIGURE 2, there is shown the presence of ilash 13 at portions 14- of the holes. This flash constitutes small pieces of rubber or other material making up the molded housing which tends to appear within the openings as a consequence of the use of prior art molding apparatus.

The particular geometry of the holes 11 shown in cross section in FIGURE 2 is determined by the manufacturers specification for the electrical pin connector itself. Thus, the holes may have different shapes in cross sections but in all cases, they Will extend usually entirely through the body 10 and thus some type of suitable structure in the molding apparatus must be provided for delining the'openings or holes. As stated, the manner in which this has been done heretofore results in the small liash 13 or pieces of rubber tending to protrude radially into the holes.

yReferring now to FIGURES 3, 4, 5, and 6, the irnproved molding apparatus of this invention wherein flash such as indicated at 13 in FIGURE 2 is eliminated will be described. Thus, referring rst to FIGURE 3, the apparatus includes basically a top plate 15, central plate 16, and bottom plate 17. The top plate 1S is secured in a stationary position as at 18 and includes a plurality of downwardly projecting pins 19 equal in number to the desired number of holes to lbe formed in the molded product.

The central plate 16 includes a cut-out opening 20 provided with an annular groove 2:1. The opening 2h serves as a material confining means orI mold for theiexterior surface such as the exterior surface of the plug 10 shown in FIGURE 1.

The bottom plate 17 includes a plurality of upwardly extending pin receiving tubes 22 having their hollow interiors communicating with an exterior-channel 23 in the bottom of the plate 17. As shown, the pin receiving tubes 22 are positioned juxtaposed the pins 19 so that when the plates are brought together, the pins will be partially telescopically received within the tubes, all as will become clearer as the description proceeds.

The top platte, center plate, and bottom plate are held in spaced relationship by means of coiled springs as indicated at 24 and 25.

When it is desired to mold a housing such as the housing 10 shown in FIGURE 1, suitable molding material 26 with a consistency approaching that of dough is inserted between the upper plate 15 and center plate 16. The plates are positioned Within a suitable press and the lower plate 17 then brought upwardly towards the center plate 16. Since the principal mass of the material 26 is between the top plate and center plate 16, it will initially tend to hold these plates separated so that the springs will lirst be compressed upon upward movement of the lower plate 17 in the direction of the arrow 27 as indicated in FIGURE 4.

With continued upward movement of the lower plate 17, the center plate 16 will move upwardly as indicated by the arrow 28 and the spring 24 will become compressed so that the material 26 is squashed downwardly within the center plate opening 20. There will be a mushrooming out of the material 26 .as indicated at 26' when the plates are substantially closed.

Any material received within the pin receiving tubes 22 will be urged out to the channel 23 as indicated by the arrows 29 in FIGURE 5. Thus, material trapped within the tubes has an egress means to the exterior of the molding apparatus.

With the plates in the position illustrated in FIGURE 5, proper curing of the material 26 is effected and upon completion, the lower plate 17 is moved away from the center plate and top plate as indicated by the arrow 30 in FIGURE 6. The pulling away of the pin receiving tubes 22 from the pins 19 from the position illustrated in FIGURE 5 to that shown in FIGURE 6 is effected in Such a manner that no flash will appear in the resulting holes. The reason for the substantial elimination of such flash will become clearer by now referring specifically to FIGURES 7 and 8.

First, with reference to FIGURE 7, the enlarged fragmentary cross section is taken just after the center plate and lower plate have moved up towards the top plate as indicated by the arrows 2'7 and 28 in FIGURE 5. Because of the relatively large area available for the material 26 to expand into, the pressure adjacent to the telescoping portions of the pin 19 and tube 22 in the region 31 is lower than the pressure elsewhere within the volume confined by the center plate opening 20. Thus, because there is room for the material to mushroom out between the center plate 16 and upper plate 1S, the tendency for the material to be forcedbetween the pin 19 and pin receiving tube 22 as at 32 into the interior of the tube 22 is decreased. Any actual material within the tube 22, however, is free to escape as mentioned in conjunction with FIGURE 5 and as indicated by the arrows 29 when 'the pin 19 itself is brought into partial telescoping relationship through the upper end opening of the tube.

With reference now to FIGURE 8, the upper end opening of the tube 22 is shown in fragmentary form as including a straight entrance portion 33 and a diverging beveled portion 34. This diverging beveled portion delines an area with the exterior lower radiused portion 35 of the pin 19 in which material may collect as at 36. The small annular area 32 between the entrance portion 33 and straight portion of the pin 19 is relatively shallow and has a depth indicated by the letter d in FIGURE 8. This may be `of the order of live thousandths of an inch.

When the pin receiving -tube 22 is pulled away from the pin 19, the material 36 will pull at any material within the annulus 32 adjacent the straight entrance portion 33 which, in the absence of the geometry of the diverging beveled portion 35, would tend to form flash. At the most, any ash that should develop will be shorter 4 than the distance d. In other words, the enlarged mass 36 pulls flash downwardly away from the defined hole during lowering of the lower plate from the center and upper plates of the mold.

With reference to FIGURE 6, when the lower plate 17 is lowered from the center plate, the spring 25 is free to expand popping up the center plate as shown. The spring 24 may then expand the center plate away from the top plate with continued lowering of the plate 17.

The plates themselves are carefully controlled when moved relative to each other so that closure is timed in accordance with the viscosity of the material employed Ito form the housing. It has been found that with the geometry of the pin receiving tubes 22 as described in detail with respect to FIGURES, substantially no ash is formed within the openings defined by the pin and tubes in the completed housing.

While only one particular example has been set forth and described, it is to be understood that various changes and modifications that fall clearly within the scope and spirit of this invention will occur to those skilled in the art. The improved molding apparatus is therefore not to be thought of as limited to the one example set forth merely for illustrative purposes.

4What is claimed is:

A molding apparatus to form a body having holes passing therethrough for housing electrical connectors, comprising, in combination: a top plate having downwardly projecting pins to define portions of said holes; a center plate having a central opening to delinethe peripheral portion of said body; a bottom plate; upwardly projecting pin receiving tubes secured to said bottom plate to dene other portions of said holes; and spring means biasing said plates apart, the tips of said pins being brought into partially telescoping position Within the upper openings of said pin receiving tubes when said plates are moved together, each of said upper openings having an inner wall defined by a straight entrance portion of given distance and thence a diverging beveled portion, said bottom plate including passage means connecting the interior of said tubes to the exterior of said plate to provide egress means for material placed in said mold and urged into said tubes, whereby flash tending to form in said holes adjacent to the telescoping portions of said tube when said body is molded is removed by material between said diverging beveled portionsV of said pin receiving tubes and end surface of said pins, said material pulling on said flash when said bottom plate is moved away from said top plate.

References Cited in the tile of this patent UNITED STATES PATENTS 1,460,299 Whitehouse lune 26, 1923 2,135,803 Dumert Nov. 8, 1938 2,222,755 Watson NOV. 26, 1940 2,275,081 Maynard Mar. 3, 1942 2,325,687 Kux Aug. 3,1943 2,341,499 Cunningham Feb. 8, 1944 2,357,407 Kurtz Sept. 5, 1944 2,363,508 yDoster et al Nov. 28 1944 2,669,753 Hormann Feb. 23, 1954 2,734,011 Robinson Feb. 7, 1956 2,937,409 Cole May 24, 1960

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