US2885651A - Terminal strip assembly and method of making it - Google Patents

Description

May 5, 1959 L. J. MOELLER TERMINAL STRIP ASSEMBLY AND METHOD OF MAKING IT Filed Sept. 1, 1954 INVENTOR. L. J MOE L (.51?

BY A 7'7'ORNEV TERMINAL STRIP ASSEMBLY AND NIETHOD OF MAKING IT Lowell J. Mueller, Towson, Md., assignor to Western Electric 'Company, Incorporated, New York, N.Y., a corporation of New York Application September 1, 1954, Serial No. 453,526

11 Claims. (Cl. 339-198) This invention relates to assemblies and methods of making them, and particularly to terminal assembhes and methods of making them.

Terminal strips are used in the telephone industry to facilitate the wiring of relay racks and other telephone apparatus assemblies requiring a multiplicity of circuit connections. One type of terminal strip consists of a :body or block of insulating cast resin having embedded therein a plurality of terminals comprising elongated rods of noncircular cross section, preferably square rods. An electrical connection suitable for use with such a tenthnal may comprise a wrapped electrical connection, such as disclosed in United States Patent 2,759,166, issued to Rudolph F. Mallina on August 14, 1956. The terminals are arranged in a number of rows each comprising a predetermined number of spaced terminals with the ends of the individual terminals projecting from opposite ends of the cast resin block.

Previously, it has been a standard practice to assemble the terminals individually by hand in intricate steel molds which held them in their proper positions. The molds were then filled with liquid casting resin which was then cured to form a rigid block around the intermediate portions of the terminals. The high initial cost of such molds and the labor required to load them made it desirable to provide an assembly in which the 'pluralities of terminals are prepositioned and held securely in the proper spaced relationship. The casting resin then may be molded around this assembly to form a finished terminal strip.

It is an object of this invention to provide new and improved assemblies, and methods of making them.

It is another object of this invention to provide new and improved terminal assemblies and methods of making them.

An assembly illustrating certain features of the invention may include a ing a plurality of spaced noncircular apertures formed therein, and a plurality of elongated rods of noncircular cross sections made of a stiff but resilient material and received within the apertures formed in the spaced plates, the rods being placed by the walls of said apertures under torsional stresses of such magnitude as to lock the plates and rods into a rigid assembly.

A method of making an assembly of a plurality of plates having noncircular apertures formed therein, and a plurality of elongated rods of noncircular cross sections made of a stiff but resilient material, which illustrates certain features of the invention, may include positioning the apertnred plates with apertures therein in alignment, inserting the rods :throngh the aligned apertures in the plates, and then subjecting of such magnitude as to lock the plates and rods into a rigid assembly.

.A complete understanding of the invention may be had om the following detailed description of a terminal strip assembly and a method .of making the same conplurality of spaced plates, each hav- I the rods to torsional stresses distance such 2,885,651 Patented May 5, 1959 in a different position and illustrating another step in the method of making the assembly, and

Fig. 4 is an enlarged, fragmentary section taken along line 4-4 of Fig. 2.

Referring now to Fig. 1, there is shown a completed, cage-like assembly 10 which includes a pair of generally rectangular-shaped end plates 11 and 12 formed from a stifi plastic material, such as polystyrene, or the like.

Each of the end plates 11 and 12 is provided with three rows of four equally spaced apertures 14-14 and 15-15. The apertures 14-14 are square in cross section, and are designed to receive closely a plurality of elongated, rodlike terminals 16-16 and 17-17 made of hard drawn brass wire, or the like, which is capable of being twisted axially and retaining a twisted set. The terminals 16-16 and 17-17, like the apertures 14-14 and 15-15 in which they are received, are square in cross section and fit snugly in those apertures.

The end plates '11 and '12 are identical and the positions of the apertures 14 14 formed in the end plate 11 correspond exactly with the positions of the apertures 15-15 in the end plate 12. In the completed assembly the end plates 11 and 1-2 are spaced apart 'a predetermined that the opposite ends of the terminals 1616 and -17-17 extend a predetermined distance beyond the o posite faces 'of the plates. Since the square apertures 14-14 and 15--'15 formed in the spaced end plates 11 and 12, respectively, are designed to match, the terminals 16-16 and 1717, when received therein, are positioned in substantially parallel relationship with respect to each other.

Priod to the assembly of the end plates 11 and 12 and the terminals 1616 and 17-17 to form the cagelike assembly 10, the terminals are individually provided with predetermined axial pretwists. To each of the terminals 16- 16 there is imparted a clockwise axial pretwist set, as viewed from the forward end in Fig. 2, of approximately 8 per inch. Similarly a counterclockwise axial pretwist set of the same magnitude is imparted to each of the terminals 17--17.

In assembling the components to form the assembly 10, the end plates 11 and 12 are brought closely together, one on top of the other, as shown in Fig. 2, with their corresponding square apertures 14--14 and 1515 in precise matching relationsh'p. Equal numbers of the pretwisted terminals 16-16 and 1717 are then inserted through the pairs of aligned apertures 1414 and 15-15 in the matching end plates 11 and 12. For the purpose of simplifying the loading operation, the two apertures 1414 and 1515 at the right hand side of each row of apertures in the end plates 11 and 12 receive the terminals 1616 which are provided with a clockwise axial pretwist. The remaining apertures 1414 and 15- 15 receive the terminals 1717 having a counterclockwise axial pretwist. Thus, six of the matching pairs of apertures 1414 in the end plates 11 and 12 receive terrninals having a clockwise axial pret'wis't and the other six receive terminals pretwisted in the opposite direction. As shown in Fig. 4, each of the apertures l t-14 and I5-'-15 of the end plates 11 and 12 is provided on one face with a tapered enlargement to facilitate the insertion of the terminals 16-46 and 17 -47 therein.

The .final step in the assembly been inserted in all of jthe end plates may be made the pairsof matching apertures 14-14 and 15-15 in accordance with the above-described arrangement, consists of separating the end plates 11 and 12 to obtain the predetermined spacing therebetween. As the end plates are moved apart, the pretwisted terminals 16-16 and 17-17 are prevented from rotating axially relative to the sides of their associated, closely fitting, square apertures 14-14 and 15-15 in the end plates. Consequently, as the end plates are separated, each of the terminals is twisted axially in a direction opposite to the direction of its respective axial pretwist. The portions of the terminals 16-16 and 17-17 between the spaced end plates 11 and 12 are untwisted to the extent that there is sub- 'stantially no twist remaining in them. However, due to the resilient properties of the pretwisted terminals 16-16 and 17-17, resultant torques are set up in the individual terminals tending to return the same to their pretwisted condition.

Since the directions of the resultant torques depend solely upon the direction of the pretwist in a particular terminal, the terminals 16-16 exert torques tending to rotate the end plate 11 in a clockwise direction, as viewed in Fig. 3, and the terminals 17-17 exert substantially equal torques tending to rotate the end plate 11 in the opposite direction. The pretwisted terminals 16-16 and 17-17 affect the end plate 12 in a similar manner. Since the resultant torques are substantially balanced, the total eflect is that the terminals 16-16 and 17-17 andthe end plates 11 and 12 are locked securely in predetermined positions relative to each other to form a rigid, self-containing, cage-like assembly 10. The action of each terminal by way of analogy might be likened to a torsion spring subjected to a torsion load.

To separate the end plates 11 and 12 in the final step of the assembly operation a certain amount of force is required depending upon the number of terminals in the completed assembly. Since work must be expended in untwisting each of the terminals, the amount of force increases directly with the number of terminals. For convenience in illustrating and describing the invention, the assembly has only twelve terminals. In actual practice assemblies having more than forty terminals have been made in accordance with the teachings of the inminals which are of circular cross section.

The pretwisting step provides the rods 16-16 and 17-17 with spirated, or corkscrew-like, portions running ,along their lengths in opposite directions, which provision enables the oppositely-acting, locking torques to be set up in the rods when the rods and plates are mutually engaged followed by relative movement between the plates to change the spacing between the plates.

It will be understood also that the invention is not limited to the materials described in connection with the foregoing exemplary embodiment thereof. Manifestly,

a plastic, provided such material is capable of resisting the deformation of the sides of the apertures formed .therein when acted upon by the resultant torques set up by the terminals held in torsion. However, in the assembly heretofore described, which is to be used in male .ing a finished terminal strip, it is desirable that the end platesbelmadeof an insulating plastic which is comalong the axes of the rods at the spirated portions thereof 1 from a material other than pati-ble with the casting resin and will adhere to it to insure a good bond between the end plates and the resin. Likewise, in nonelectrical applications, where it is not necessary to have conductive terminals, the metal terminals might be replaced by rods of any suitable material having the requisite resilient properties and capable of retaining the necessary pretwist set.

What is claimed is:

1. An assembly which comprises a pair of spaced plates having a plurality of spaced apertures formed therein, and a pair of elongated rods made of a stiff but resilient material and pretwisted axially in opposite directions, each of said rods being received at itsopposite ends within apertures formed in the spaced plates with the portion thereof between said plates untwisted axially and held in torsion by the walls of the apertures, whereby resultant torques are set up in the rods which efiectively lock the plates and rods together.

2. An assembly which comprises a plurality ofelongated rods made of a stiff but resilient material having a noncircular cross section, some of said rods being provided with an axial pretwist of one hand and the remaining rods having an axial pretwist of the opposite hand, a pair of spaced plates having formed therein pluralities of noncircular apertures within which the opposite ends of said pretwisted rods are received, the portions of said rods between the spaced plates being untwisted axially and restrained from returning to their pretwisted sets by the walls of the apertures, whereby resultant, oppositelyacting torques are set up in the rods which effectively lock the plates and rods together.

axial pretwist of the opposite hand, and a pair of spaced plates provided with a plurality of noncircular apertures designed to receive the rods and prevent them from tuming axially therewithin, said pretwisted rods being received within corresponding pairs of aligned apertures in the spaced plates with the portions of the rods extending between the plates untwisted axially and restrained from returning to their normal pretwisted sets by the walls of the apertures, whereby resultant, substantially equal and oppositely-acting axial torques set up in the rods effectively lock the plates and rods together.

4. A terminal strip assembly which comprises a plurality of elongated terminals having generally rectangular cross sections and made of a stiff but resilient, electrically conductive metal, one half of the terminals having been provided with a predetermined clockwise axial pretwist and the remainder having a counterclockwise axial pretwist of equal magnitude, and a pair of spaced endplates made of an electrical insulating material provided with a plurality of generally rectangular apertures designed to closely receive the terminals and prevent them from turning axially therewithin, said pretwisted terminals being received within corresponding pairs of aligned apertures in the spaced endplates and having the intermediate portions thereof extending between the endplates untwisted axially and restrained from returning to their normal pretwistedsets by the walls of the apertures, whereby the resultant, substantially equal and oppositely-acting axial torques set up within the terminals efiectively lock the endplates and terminals together.

5 A terminal strip assembly which comprises a plurality of elongated terminals having generally rectangular cross sections and made of a stiff but resilient metal, one ,half of. the terminals having been provided with a pre' determined clockwise axial pretwist and the remainder having'a' counterclockwise axial pretwist of equal magnitude, and'a pair of spaced plastic endplates provided with -a plurality of equally spaced, generally rectangular apertures designed to closely receive the terminals and prevent them from turning axially therewithin, said pretwisted terminals being received within corresponding pairs of aligned apertures in the spaced endplates and having the intermediate portions thereof extending between the endplates untwisted axially and restrained from returning to their normal pretwisted sets by the walls of the apertures, whereby the resultant, substantially equal and oppositely-acting axial torques set up within the terminals efiectively lock the endplates and terminals together.

6. The method of making an assembly of a pair of plates having matching noncircular apertures therein and a pair ofelongated rods of noncircular cross sections made of a stifi but resilient material, which comprises positioning the apertured plates in close proximity with the apertures therein in alignment, imparting predetermined axial pretwists to the rods in opposite directions, inserting the pretwisted rods through the aligned apertures in the plates, and separating the plates through a predetermined distance, whereby the portions of said pretwisted rods extending between the spaced plates are untwisted axially and held in torsion by the walls of the apertures to set up resultant, oppositely-acting torques in the rods, which efiectively lock the plates and rods together.

7. The method of making an assembly of a pair of plates having a plurality of matching noncircular apertures formed therein and a plurality of elongated rods of noncircular cross sections made of a stifi but resilient material, which comprises positioning the apertured plates in close proximity with the apertures therein in alignment, imparting predetermined axial pretwists in one direction to substantially one half of the rods, imparting axial pretwist of substantially the same magnitude in the opposite direction to the remainder of the rods, inserting the pretwisted rods through the aligned apertures in the plates, and separating the plates through a predetermined distance, whereby the portions of said pretwisted rods extending between the spaced plates are untwisted axially and held in torsion by the walls of the apertures to set up within the rods resultant, oppositely-acting torques which effectively lock the plates and rods together.

8. The method of making an assembly of a pair of plates and a pair of elongated rods of noncircular cross sections made of a still? but resilient material, which comprises providing each plate with a pair of noncircular apertures adapted to receive the rods and to prevent them from turning axially therein, positioning the apertured plates in close proximity with the apertures therein in alignment, imparting predetermined axial pretwist to the rods in opposite directions, inserting the pretwisted rods through the aligned apertures in the plates, and separating the plates through a predetermined distance, whereby the intermediate portions of said pretwisted rods extending between the spaced plates are untwisted axially and held in torsion by the walls of the apertures to set up resultant, oppositely-acting torques in the rods, which lock the plates and rods together.

9. The method of making an assembly of a pair of plates having a plurality of matching noncircular apertures formed therein and a plurality of elongated rods of noncircular cross sections made of a stifi but resilient material, some of said rods having a permanent axial pretwist in one direction and the remainder having a permanent axial pretwist in the opposite direction, which comprises positioning the apertured plates in close proximity with the apertures therein in opposing positions in which the apertures are aligned, inserting the pretwisted rods through the aligned apertures in the plates, and sep aratin g the plates through a predetermined distance, whereby the portions of said pretwisted rods extending between the spaced plates are untwisted axially and held in torsion by the walls of the apertures to set up within the rods resultant, oppositely-acting torques which effectively lock the plates and rods together.

10. The method of making an assembly of a plurality of plates having noncircular apertures therein, and a plurality of elongated rods made of a stiflf but resilient material and having noncircular cross sections designed for close reception within corresponding apertures in the plates, which comprises imparting predetermined axial pretwists in one direction to certain of the rods and in 0pposite direction to the remaining rods, mutually engaging the pretwisted rods and the plates so that the rods extend between the plates and are received within the corresponding apertures in the plates, and causing relative movement between the plates along the axes of the rods to change the spacing therebetween so that resultant, oppositelyacting torques are set up in the rods which are directed against the material of the plates defining the apertures for effectively locking the plates and rods together.

11. The method of making an assembly of a plurality of plates having noncircular apertures therein, and a plurality of elongated rods made of a stiff but resilient material and of noncircular cross section designed for close reception within corresponding apertures in the plates, which comprises providing certain ones of the rods with spirated portions running along their lengths in one direction and the remainder of the rods with spirated portions running in the opposite direction, mutually engaging the rods and the plates so that the rods extend between the plates and are received within the corresponding apertures in the plates, and causing relative movement between the plates along the axes of the rods at the spirated portions thereof to change the spacing between the plates so that resultant, oppositely-acting torques are set up in the rods which are directed against the material of the plates defining the apertures for efiectively locking the plates and rods together.

References Cited in the file of this patent UNITED STATES PATENTS 1,750,039 Feltes Mar. 11, 1930 1,808,040 Hyatt June 2, 1931 1,917,573 Black July 11, 1933 1,977,299 Bates Oct. 16, 1934 2,405,180 Blattner et al. Aug. 6, 1946 2,420,842 Schymik May 20, 1947

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