US2087311A - Composite article and method of making composite articles - Google Patents

Description

July 20, 1937. E. WENSLEY 2,087,311

COMPOSITE ARTICLE AND METHOD OF MAKING COMPOSITE ARTICLES Filed Oct. 6, 1934 WE/VSLEY @y fsf-@wmv Patented July 20, 1937 COMPOSITE ARTICLE AND METHOD OF MAKING COMPOSITE ARTICLES Earl Wensley, Chicago, Iii., assigner to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application October 6,

Claims.

This invention relates to composite articles and methods of making composite articles, and more particularly to terminal banks for rotary telephone switches.

One type of terminal bank used in telephone selector switches includes a plurality of superimposed or piled up rows of individual terminals arranged in groups of two rows spaced a desired distance apart by an insulator blank, the terminais of each row being uniformly spaced in a lateral direction. Each group of terminals is spaced from the adjacent group a desired distance by a pair of spaced insulator blanks and a metal ground plate filling the space between the blanks. The Whole pile-up of uniformly spaced groups of terminals with their insulator blanks and ground plates is clamped under pressure between upper and lower mounting plates with the terminals projecting on either side from the insulator blanks and the ground and mounting plates. In this type of terminal bank it has been dilcult to provide a uniform desired spacing between the two rows of terminals of each group as well as between the groups due to variations in the thickness of the individual insulator blanks used in the pile-up. Furthermore, it has been the practice to rely chiefly on the carefulness in carrying out the assembly operations to prevent the individual terminals from being dislocated during their initial assemblage in the pile-up and in their final assemblage the pressure exerted on the clamped pile-up has been relied upon to maintain the individual terminals in their desired spaced relation.

Objects of the present invention are to provide an improved composite article wherein the parts thereof have a desired spacing and are firmly united to prevent relative displacement therebetween and to provide an effective and economical method of manufacture.

In accordance with the above objects, wherein one embodiment of the invention is applied to the production of terminal banks of the type hereinbefore referred to, the terminal banks are l `built up from a plurality of previously formed terminal units, each unit comprising a row of terminals adhered to an insulator support of a selected thickness. Specifically, each unit comprises a completely cured phenol fibre strip or blank of a desired thickness and contour to form a support for the unit. The term phenol bre blank will be described in detail hereinafter. Upon the top of the fibre blank is placed one or more strips or blanks of fabric, such as muslin, impregnated with a black asphaltum composi- 1934, Serial No. 747,124

(Cl. Mii- 306) tion and coated upon opposite surfaces, after the asphaltum has dried, with a good quality varnish containing tung oil, which is allowed to harden or set. The muslin blanks have a contour similar to that of the fibre blank and a desired thickness. The phenol fibre and muslin treated blanks for each terminal unit are selected for thickness so as to provide a desired overall height at the completion of their assemblage. Thereafter the conducting terminals are deposited in a desired spaced arrangement 'upon the top of the muslin blank, which together with the supporting phenol fibre blank are supported on a fixture. The superimposed phenol fibre and muslin blanks with the terminals are then placed between heating and compressing members and subjected to heat and pressure to bring them to a desired overall height, during which the varnish upon opposite surfaces of the muslin blanks is rst softened and upon subsequent cooling, while pressure is maintained, the softened varnish sets. This results in a unit of a desired overall height, with the muslin blanks adhering to each other upon their abutting surfaces, and the terminals adhering and firmly embedded slightly in one surface of the muslin thickness, the opposite surface of the muslin thickness adhering to the abutting surface of the phenol bre support. The method of assembling the units into a completed terminal bank will be described in detail hereinafter.

Other objects and advantages of this invention will more fully appear from the following description taken in connection with the accompanying drawing, wherein Fig. 1 is a top plan view of an assembled terminal bank comprising a plurality of superimposed composite terminal units embodying the features of and produced in accordance with a method of this invention;

Fig. 2 is an enlarged fragmentary vertical section taken on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary vertical section, still further enlarged, taken on the line 3-3 of Fig. 2, and

Fig. 4 is a side View of a fixture for assembling the phenol fibre and treated muslin blanks in superimposed desired relation, and with the conducting terminals shown deposited thereon.

A terminal bank comprising a plurality of superimposed composite terminal units embodying the features of this invention may be produced by rst producing a number of arcuateshaped strips or blanks l0 and H of different areas and thicknesses, each serving in the finished terminal bank in a particular manner which will be referred to hereinafter. The blanks I0 and II are formed from sheets of different areas and thicknesses, comprising laminations of fibrous material, such as paper or fabric, each lamination thereof having been impregnated with a phenolic condensation product and the whole united and completely curved by the application of heat and pressure to produce a sheet of an incompressible, infusible, and insoluble character and a desired accurate thickness, within tolerance limits, the blanks I0 and II then being cut from the sheets. The sheet material just described is commonly known as phenol bre.

A plurality of strips or blanks I4 of fabric, such as muslin of the same contour as the arcuateshaped phenol bre blanks i0 are cut from sheets of muslin having a desired accurate thickness, within tolerance limits, and with a minimum of moisture content, previously impregnated with a black asphaltum composition, or an equivalent medium, and the sheets after drying are coated upon opposite surfaces with a good quality varnish which includes suiiicient tung oil that after drying or setting it will be flexible and nonbrittle, but upon the application of heat it will rapidly change from a dry to a` tacky state and upon the removal of heat it will slowly change from a tacky toa dry hardened state, thus giving it good adhesive qualities. The coating of varnish applied to the impregnated muslin sheets from which the blanks I4 are cut is non-tacky at atmospheric conditions and has excellent electrical insulation properties at high humidities. Any good quality spar varnish, such as Valspar when mixed with suiiicient tung oil that the resultant solution will consist of approximately nine parts of varnish and one part o-f tung oil, has been found suitable for coating the opposite surfaces of the impregnated muslin sheets from which the blanks I4 are cut.

Each terminal unit in the embodiment illustrated includes ten conducting terminals I5 of a desired thickness and contour which may be formed from brass sheets. At the rear each terminal is extended and offset to form a soldering portion IB.

Referring particularly to Figs. 1 and 2, a plurality of perforations I1 are 'formed in the phenol fibre blanks I0 and II and the treated muslin blanks I4, which inthe assembly of the blanks with the conducting terminals I5 into a terminal unit are alined, the perforations being used in the assemblage and alining o-f the blanks into terminal units and subsequently in the assembling of a plurality of terminal units into a finished terminal bank.

In uniting the phenol fibre blank IIJ and in the embodiment illustrated two asphaltum impregnated muslin blanks I4, coated upon opposite surfaces with a solution of Vvarnish and tung oil, previously described, and a set of ten terminals I5 into an integral terminal unit, the blanks I0 and I4, which are selected as to thickness so as to provide a desired overall height when assembled with the terminals I5 and thereby an accurate and uniform spacing between the rows of terminals, are assembled in superimposed relation upon a fixture (Fig. 4) comprising a base I8 having a plurality of vertically disposed metal alining pins I9 which extend freely through the perfcrations l1 formed in the blanks. Thereafter the assembling fixture carrying the alined blanks III and I4 is correctly located under a mechanism (not shown) which includes ten supply magazines for the terminals I5 andten. alined nests or guides, one, in each instance, for each of the terminals for respectively supplying to and locating the terminals on top of the upper muslin blank I4 in their accurate desired positions thereon. The mechanism is then operated and ten terminals i5 are deposited in a predetermined position on top of the upper muslin blank I4, their relative positions being shown in Fig. l. The assemblage of superimposed blanks IU and I4 and the terminals I5 still mounted on the iixture with the pins I 9 thereof extending through the alined perforations I'I of the blanks is then inserted between heating and compressing members (not shown) the projecting ends of the pins I9 being alined with suitable apertures provided in the adjacent heating and compressing member.

The heating and compressing members are then relatively moved to compress the assemblage of superimposed` blanks I0 and I4 and the terminals I5 until a desired overall height of the superimposed blanks and terminals is reached, which is reached when stop surfaces on the members engage each other. During the compression heat is applied to soften to a desired degree the hard coating of varnish and tung oil on the oppcsite surfaces of the superimposed muslin blanks I4 by suitably heating the heating and compressing members either before inserting the assemblage of blanks and terminals therebetween or simultaneously with their compression. Thereafter the superimposed assemblage of blanks III and I4 and the terminals I5 are cooled either by room temperature after ceasing to apply heat to the heating and compressing members or by applying a cooling medium thereto by suitable means and simultaneously therewith the compressive actionon the superimposed blanks and terminals is maintained. The finished terminal units are indicated by the numeral 20 (Figs. 2 and 3).

With the termination of the cooling step the asphaltum impregnated muslin blanks I4, which are exteriorly coated with the varnish and tung oil solution, are firmly united to each other upon their abutting surfaces and the terminals I5 are firmly united to and firmly embedded slightly in one surface of the muslin thickness, as clearly shown in Fig. 3, and the opposite surface of the muslin thickness is firmly united to the abutting surface of the phenol fibre blank due to the adheslve action of the softened varnish and tung oil solution between the adjacent parts of the assemblage, which solution upon the setting or baking thereof becomes hard and provides a firm bond between the parts. The resultant integral structure has a desired overall height and the terminals I5, due to their adherence to the top surface of the muslin thickness, will not be dislocated in subsequent handling of thc terminal units 20 prior to or during their final assembling operations into a finished terminal blank. The asphaltum impregnated and varnish coated muslin blanks I4 obviously provide ayieldlng medium between the terminals I5 and the incompressible phenol fibre blank I0 which permits greater tolerances in the thicknesses of the selected blanks I Il,

- since variations in the thickness .of the blanks I5 comprising the terminal unit 20, no change in the individual thickness of the blanks I0 occurs,

y since the blank, as hereinbefore described, has

may be performed in any convenient apparatus a disclosure of a. speciiic apparatus for accomplishing these operations is not believed necessary to a full understanding of this invention and have been omitted.

If desired the terminals I5, as well as the insulating blanks IIJ and I4, may be placed in the assembling fixture by hand. In such case the assembling fixture may be provided with suitable guides adjacent its edges for properly positioning the terminals.

In producing a terminal bank, referring particularly to Figs. l and 2, which includes a pileup of predeterminedly spaced and alined terminal units of the type previously described, there are provided top and bottom mounting or clamping plates 22,of metal, the top plate only being shown. The plates 22 are arcuate-shaped and formed With a plurality of perforations 23 similar to and spaced for alinement with the perfora- Itions Il formed in the phenol fibre blanks IU and II and the treated muslin blanks I4. In assembling the bank the bottom plate is first positioned on an assembling xture (not shown) provided with a plurality of vertically disposed metal alining pins which register with the alined perforations of the various terminal units 20, spacers, and plates used in building a finished terminal bank. Upon the top of the lower clamping plate 22 is positioned a terminal unit 2D and upon the top of the latter a phenol iibre blank II of the type previously described. Another terminal unit 20, only reversed in position so that the lower surfaces of the conducting terminals I5 will abut the upper surface of the phenol fibre blank II, is then positioned on top of the latter blank. This is followed by placing an arcuate-shaped perforated metal ground plate 24 of a desired thickness on the upper surface of the phenol fibre blank I0 of the last positioned terminal unit 20. Thereafter another terminal unit 20 with the terminals I5 thereof uppermost is positioned on the top of the ground plate 24 and then the order of assembly of the terminal units 20, phenol bre spacer blanks II, and ground plates 24 is continued until the desired number of terminal units have been superimposed upon the pins of the assembling fixture to pro-Vide a terminal bank of the desired number of terminals. Upon the uppermost terminal unit 20 of the bank the upper mounting or clamping plate 22 is positioned. The assembly is then removed from the pins of the xture and While maintaining the parts alined, bolts 25 are passed through the alined perforations of the blanks and plates and then tightened until the required overall height of the assembled terminal bank is reached.

The upper and lower mounting or clamping plates 22 are formed with the usual perforations 26 in order that the terminal bank may be secured to the switch frame. It will be noted, referring to Fig. 1, that the conducting terminals I5, which are disposed close to the bolts 25, are

notched, as'indicated at 2T, upon opposite edges and in linel with the bolts so that no short cir= cuit or path of low conductance between the terminals and the bolts at this point can occur.

From the above description it will be apparent that by practicing the method of this invention a terminal bank may be economically and efll.- ciently produced wherein the several rows of terminal units predeterminedly spaced from each other by insulating and metal spacing strips and plates, respectively, of selected accurate thicknesses will have a desired accurate spacing upon complete assemblage into a bank and the individual terminals of each row will be maintained rmly in their desired laterally spaced relation. This primarily results from' the described method of building the individual terminaly units from superimposed completely cured phenol fibre and asphaltum impregnated fabric strips of selected thicknesses and having the described surface coating of varnish on the fabric strips with the conducting terminals accurately arranged on top of the fabric strips. The whole superimposed structure comprising the terminal unit is thus formed into a rmly united composite structure of a desired overall height wherein the several strips and terminals are firmly bonded to each other due to the adhesive action of the varnish coating on the fabric strip upon completion of the heating, compressing and cooling stepsof the f method.

While a manual method of assembling the units 20 into completed banks has been described, the terminals are suiiciently firmly attached to the insulating strips that if desired machine methods of assembly may be used.

While the foregoing describes but one embodiment of a composite article produced in accordance with the method of this invention, it will be understood that the invention is capable of application to other types of articles and is only limited by the scope of the appended claims.

What is claimed is:

1. A composite article comprising a base element of insulation and laterally spaced electrical conducting members, and a hard filler between the abutting surfaces of the elements and the members comprising a mixture of spar varnish and approximately ten percent of tung oil, the

'erally spaced electrical conducting members, the

abutting surfaces of the elements and the outer parallel surface of the element abutting the members having a hard coating comprising a mixture of spar varnish and approximately ten percent of tung oil, the whole superimposed structure being formed into an integral composite article.

3. A composite unit for use in building terminal banks comprising a plurality of superimposed layers of insulation, the top layer being of asphaltum impregnated fabric having a hard surface coating comprising an adhesive composition at opposite sides, and a layer of laterally spaced metal terminal members on top of the fabric layer, the whole superimposed structure being an integral composite article of a desired overall height.

e. A terminal bank for telephone exchange systems comprising a pile-up of integral composite preformed terminal units alternately reversed in position and alternate elements of insulation and electrical conducting material of a predetermined accurate thickness between successive terminal units, said terminal units each comprising Aa base element of insulation and a single layer of laterally spaced electrical conducting members of selected thicknesses, and compressible adhesive spacing means between the abutting surfaces of the members and element for adhering them to each other to provide an integral composite terminal unit of a desired overall height, and tension members for uniting the pile-up into a unitary terminal bank, said terminal units and alternate spacing elements remaining separate and distinct from each other.

5. An electrical terminal bank comprising a plurality of assembled units each comprising a substantially incompressible layer of insulating material, a layer of thermoplastic material and electrical conducting elements embedded in said thermoplastic material, the units being individually preformed to a denite thickness whereby the spacing between said electrical conducting elements is rendered uniform.

6. A method of making a terminal bank which comprises superimposing a layer of a thermoplastic material and a layer of a substantially incompressible material, placing electrical conducting elements thereon, subjecting the assembly to heat and pressure to consolidate the assembly into a unit of denite thickness, and assembling a number of such units into a terminal bank.

'7. A composite article adapted to be assembled with a plurality of similar articles superimposed thereon, comprising a substantially incompressible layer of insulating material, a layer of insulating material of a type which can be formed during assembly, and a single row of conducting elements embedded in said formable insulating material, Asaid article being preformed to a definite thickness whereby when assembled with similar articles the spacing between successive rows of conducting elements will be uniform.

8. A composite article adapted to be assembled with a plurality of similar articles superimposed thereon, comprising a substantially incompressible layer of insulating material, a layer of fabric impregnated with thermoplastic material, a layer of insulating material of a type which can be formed during assembly superimposed on said fabric, and a single row of conducting elements embedded in said iormable insulating material, said article being preformed to a denite thickness whereby when assembled with similar articles the spacing between successive rowsA of conducting elements will be uniform.

9. A method of making a terminal bank which comprises superimposing a layer of a thermoplastic material, a layer of fabric impregnated with a thermoplastic material and a layer of a substantially incompressible material, placing electrical conducting elements thereon, subjecting the assembly to heat and pressure to consolldate the assembly into a unit of denite thickness, and assembling a number of such units into a terminal bank.

l0. A composite unit for use in building terminal banks comprising a plurality of superimposed layers of insulation, the top layer being of fabric impregnated with an insulating composition and having a hard surface coating comprising an adhesive composition at opposite sides, and a layer of laterally spaced metal terminal members on top of the fabric layer7 the whole superimposed structure being an integral composite article of a desired overall height.

EARL WENSLEY.

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