US2591881A - Method of making radio speakers - Google Patents

Description

April 8, 1952 B. T.'SETCHELL 2,591,881

7 I 7 METHOD OF MAKING RADIO SPEAKERS v 7 Filed Feb. 28, 1947 4 Sheets-Sheet 1 BARTON T. SETC HELL mag April 8, 1952 B. 'r. SETCHELL 2,591,881

' YMETHQD OF MAKING RADIO SPEAKERS Filed Feb. 28, 1947 4 Sheets-Sheet 2 grwmvbom Z BARTON T. SETcHsu.

' B. T. SQYETCHELLT METHODOF MAKING RADIO SPEAKERS Aim-i1 s; 1952 Filed Feb. 28, 1947 v 4'Shee ts-Sheet 3 F]. E. S

A 3mm BARTON T. SETCHELL 8% @M m Emma awe/mm;

B. T. SETCHELL METHOD OF MAKING RADIO SPEAKERS April 8, 1952 4 Sheets-Sheet 4 Filed Feb. 28, 1947 ELLE. .LEI

gwumvkw BARTON T. SETC HELL 3g WRXEJM FlE. 5

speaker pot.

M It is an object of the present vide a means of applying a coat of adhesive to the "surface of the coil wire during the formation of "partment. .dermic needles on opposite sides of the adhesive --compartment-through which the wire is guided ---duringits entrance to and exit fromthe adhesive Hchambenp Patented Apr. 8, 1952 Barton T. Setchell. St. Paul, Minn. Application February 28, 1947. Serial No. 731,579

2 Claims.

My invention relates to an improvement in apparatus for making radio speakers and the like, wherein it is desired to reduce the'cost of manufacture of these articles.

In the manufacture of radio speakers, it is common practice to employ a diaphragm formed the same. This coil must be positioned and formed with extreme accuracy if the speaker is to operate properly in view of the fact that the coil 29-15557) r j .i

An added feature of the present invention. resides in the provision of a rotatable spindleon which the speaker diaphragm may be mounted of fibrous material and to secure to this dia phragm a paper core having a wire coil encircling must be received in a narrow circular gap between I the polepiece and an encircling aperture in the Considerable difficulty is experienced in properly forming these coils and in properly positioning the coils on the speaker diav phragm. p

invention to prothe coil. In the past it has beenu'sual practice 7 to apply a coating of adhesive to the ring shaped paper core on which thecoil is wound, to Wind during the formation of the paper core; .This spindle is provided with a core about which :the paper sleeve supporting the coil maybe wrapped. This paper sleeve is wrapped about the mandrel and adhered to the surface of. thediaphragmwith a suitable cement. Means are'provided for regulating the length of the coil wrappedthereabout so that the desired number of turns is provided on the'coil. l

A further feature of the present invention lies in the provision of a movable adhesive chamber through which the wire is drawn before it; is

wrapped aboutfthe paper sleeve. The adhesive member is movable so that theiwiremay follow 3'. substantially straight path while travelling fromthe source of supply into. winding position.

One of the primary difficulties experienced in the coil on'this core, and to apply a second coat of adhesive over the surface of the coil. By applying the adhesive directly to the wire, the

necessity of stopping to apply successive coats of adhesive to the paper and coil is obviated; thus thespeaker pot'to be of minimum width.

'An added feature of the present invention lies in the provision of a means for automatically apsembly of the speaker.

proper formation of the voice coil and in maintaining this coil in proper shape during thetgas- It ,is usual practice. Ito form the voice coil over acollapsible'mandrel either with or without its paper core andg-tojapply a suitable adhesive to the surface of lthis coil 'after the formation thereof. Some time is required for'this adhesive to set and the adhesive has'somewhat of a tendency to contractas it dries. Furthermore the wire itself is'stretched 1 during the formation of thecoiland tendsto return to its original shape,thus tending to distort the coil. It is usually impractical to maintain plying a jfilm of liquid adhesive to the surface of v 'a wireas the wire is used. As the wire is removed from the spool it is directed through a chamber filled with adhesive, thereby coating all f surfaces of the wire with the adhesive. As the wire travels from the adhesive chamber; it passes through an aperture slightly larger-in diameter partment through which wire may be drawn.

The apertures are so small in size that the adhesive will not run or flow from the adhesive compartment even though the apertures are substantially below the adhesive level in the com- In preferred form I employ hypothe coil on the mandrel until the adhesivehas dried due to the time element involved. Asf-a result the moist adhesive,- the resilience of; the

:, wire, and the movement of the mandrel tend to distort the coil as it is removed from the'gmandrel.

"Furthermore the handling of the coilwhilesupported only by'its thin paper sleeve-tends todistort the coil betweenthe time it is formed and the time it is attached to the diaphragm. :Ifthe coil is out of round it does not properly fit-between the pole piece and the speaker pot unless an unusuallywide gap is provided, thus impeding the efiiciency of the speaker. .Ly

It is an important feature of the presentginvention to form the coil on a-m'andreland to hold the coil thereuponuntil the adhesive is entirely dry. The coil is formedabout the paper sleeve after the-attachment of this sleeve to the diaphragm and the sleeve is held in cylindrical form l by-the mandrel about which; it is wrapped during a large part of the speaker assembly operation. Beforethe diaphragmand coil-areremoved from the supporting mandrel the adhesive is completely dried by infra red lamps or other suitable means, thus insuring the proper shape of the coil and minimizing the handling thereof before the speaker is completely assembled.

An added feature of the present invention resides in the provision of a means for reversing the direction of wind of the wire so that a coil of two thicknesses of wire is provided. The paper sleeve which forms the core is so formed as to be thicker on one end than on the other. The wire is wrapped about this sleeve or the portion thereof of lesser thickness. When the wire reaches the end of the coil, means is provided for reversing the direction of the wire so as to provide a layer of wire overlying the innermost layer.

An added feature of the present invention lies in the provision of a mandrel on which thespeaker may be assembled to insure the proper relationship of the parts and'to prevent fracturing of the diaphragm during the assembling operation. This mandrel is designed to support the diaphragm so that the paper sleeve can be attached thereto at the center thereof. The coil is next wound about the sleeve so that the coil is properly positioned at the center of the diaphragm. Means is provided near the periphery of the mandrel and externally of the diaphragm for holding the ends of the wire coil to insure the drying of the adhesive. The mandrel may also be used to hold the diaphragm while the ends of the coil are anchored and soldered to suitable leads.

These and other objects and novel features of the present'invention will be more clearly and fully set forth in the following specification and the adhesive chamber showing the manner in which the adhesive is applied to the wire as it passes through the chamber.

I Figure 4 is a sectional view through the speaker diaphragm at the beginning of the assembly operation.

Figure 5 is a diagrammatic view of a paper strip which may be used to form the core of the coil'attached to the diaphragm.

Figure 6 is a side elevation view of the speaker diaphragm with the paper coil, core and coil attached thereto.

Figure 7 is an enlarged view showing the mandrel on which the diaphragm is mounted during the formation of the coil thereupon.

Figure 8 is a front elevational view of the diaphragm and mandrel at the completion of the coil winding operation.

Figure 9 is a view similar to Figure 8 showing (ill the manner in which the ends of the coil are,

anchored to suitable leads or conductors.

Figure 10 is a view similar to Figure 9 showmg the completion of the coil forming operation,

Figure 2 of the drawings. In this figure is i1- lustrated a supporting standard l0 mounted upon a base or table H and including a pair of spaced uprights [2 connected at their upper extremity by a cross member l3. A pair of arms M are supported in any suitable manner by the cross member [3 to rotatably support a spool IS. A substantially V-shaped brace [6 having a roll er I! at its lower extremity acts as a guide for the wire l9 in its movement from the spool 15 to winding position.

The coil winding apparatus also includes a shaft or spindle 20 mounted on spaced supports such as 2| and provided with an operating pulley 22 on one end thereof. The pulley 22 is driven by a belt 23 extending over a suitable pulley 24 on the drive shaft of a motor 25. When the motor 25 is in operation the belt 23 acts to rotate the shaft or spindle 29. v

An upright 26 is provided adjacent the support 2| which upright supports a rearwardly extending shaft or pivot 21. An adhesive conductor 29 is provided with a pair of upwardly extending brackets 30 which pivotally engage about the shaft 21. A filling opening 3| is provided at the top of the conductor 29 and a tubular sleeve 32 extends downwardly from the conductor 29 and is closed at its lower extremity by a plug 33 having a guide arm 34 integral therewith.

The tubular-member 32 is provided with a pair of aligned opposed apertures 35 and 38 therein which are tapped to receive the externally threaded end of a suitable hypodermic needle fitting 31 or 39. The fittings 3'! and 39 respectively support the hollow hypodermic needles 40 and M which extend in aligned opposed relation in opposite directions from the tubular member 32. l

The hypodermic needles 40 and M are of proper internal diameter to receive the wire 19 and to allow the wire to pass freely therethrough. At least the needle 40 is of sufficient internal diameter to permit the wire to be carried from the adhesive chamber 42 within the tubular member 32 without scraping all of the adhesive from the surface of the wire.

It will be seen that as the wire 19 is drawn from the spool I5 itis carried through the adhesive chamber 42 and coated on all surfaces with liquid adhesive. The wire l9 then passes through the needle 40 where just sufficient adhesive remains on the wire to properly adhere the wire to the coil and in coiled formation.

The uniform coating of adhesive is not sufficient to greatly increase the diameter of the coil and all of the coils are of similar diameter in view of the even coating of adhesive on the wire.

-Either or both of the needle fittings 31 and 39 may be removed before the start of the coating operation so that the wire [9 may be threaded therethrough without difficulty. In usual practice the wire I9 is threaded through the needle 41 and through the opposed aperture 35 in the tubular member 32-while the needle fitting 31 is removed. The wire is then inserted through the hypodermic needle 40 from the inner end thereof, thus providing a continuous path for the wire through the body of adhesiv In the formation of speaker units the diaphragm 43, best illustrated in-Figure 4 of the drawings, is mounted upon a mandrel 44 illustrated in Figure 7 of the drawings. The diaphragm 43 usually includes a central flange'45 which is centered in respect to a circular peripheral flange 46. The body of the diaphragm 43 is generally cone shaped between the flange 45 and the flange 46 comprising a tapered body 41 having a series of circular corrugations 49 extending thereabout between the cone-shaped body 41 and the flange 46. Additional steps may be provided if desired in the cone shaped body to render the cone properly flexible to produce the desired sound.

A paper sleeve or tab is secured to the diaphragm 43. This sleeve is formed of a paper strip 50best illustrated in Figure 5 of the drawings/ The strip is of proper length to form a sleeve of two laminations throughout half its length, and of a single thickness throughout the remainder of its length. The portion 5| of the strip forms the inner lamination and the portion 52 forms an outer lamination throughout part of the length of the sleeve. The double thickness or reinforced end of the sleeve 50 is secured to the diaphragm, with the single thickness portion on the free end of the sleeve to support the wire coil.

In attaching the paper core or sleeve 50 to the diaphragm 43, the paper sleeve is wrapped about the projecting shank 53 of the mandrel 44. After the sleeve is in place on the shank 53, the diaphragm 43 is inserted over the sleeve to hold the sleeve in coiled relation. Adhesive is applied at 54 at the juncture between the paper sleeve and the flange 45 of the diaphragm. This is usually accomplished by wrapping the paper about the shank 53 during rotation of the shank, inserting the diaphragm 43 in place, forcing adhesive by an suitable means at the juncture of the sleeve and diaphragm during rotation thereof. The sleeve is thus attached to the diaphragm and the coil is in readiness to be formed. The wire I9 is then anchored in a coil spring 55 mounted near the periphery of the flange 56 at the outer margin of the mandrel 44. The wire is drawn adjacent the shoulder 51 formed between the single thickness portion of the sleeve 50 and the double thickness portion thereof and the mandrel 44 is rotated to wind the wire I9 about the single thickness portion of the sleeve 50.

Prior to the coil winding operation a coil limiting sleeve 59 is engaged on the end of the shank 53. The sleeve 59 is provided with a peripheral flange 60 by means of which the sleeve may be rotated, an internally threaded portion 6| to engage on the externally threaded portion 62 of the shank 53, and a projecting sleeve portion 63 which is undercut to engage over the end of the sleeve 50. This projecting sleeve portion 63 limits the length of the coil. As a result when the wire I9 has been wound about the single thickness portion of the sleeve 50 until the wire engages the projecting sleeve portion 53, the wire will build up on the first layer nd start a reverse winding overlying the first winding mentioned. This reverse winding is continued until the wire reaches the double thickness portion of the sleeve 50 whereupon rotation of the mandrel 44 is stopped, the coil wire broken off at a point spaced from the core and the end. of the wire limitin sleeve forms a shoulder which will automatically terminate the inner coil layer and start.

It is onl necessary four the second coil layer.

the operator to guide the wire during the coilingj '"tion of the paper core.

operation and to stop the rotation when the second coil layer reaches the double thickness por- As a result the task of "forming the coil on the diaphragm is greatly simplified and the speed of operation is greatly increased. Furthermore, the coil may be properly wound by a relatively unskilled worker. In

' Lead wires or conductors I0 and II are likewise inserted into the eyelets 66 and a drop of solder or similar material is placed upon each eyelet to electrically connect the coil ends 61 and 69 to the lead wires I0 and II and to anchorthe ends of the coil. The lead wireslli and. 1| are connected in the proper circuit so as to produce electrical impulses through the wire coil I9. .As

, soon as the lead wires have been properly attached a spider of fabric or the like, indicated by the numeral I2, is inserted over the sleeve 50 and coiled to encircle the joint between the paper core and the diaphragm 43. Adhesive is applied about the inner periphery of the fabric spider I2 to adhere this member to the diaphragm 43.

During the preceding process, the tab or sleeve 50, the diaphragm 43, the voice coil, the coil leads, and the spider are applied in sequence. In volume assembly, the various steps are followed by diflerent workers, so that the adhesive holding the coil tab or sleeve to the diaphragm and the adhesive on the coil wire have some time to set before the spider is applied. In order to insure proper drying of the adhesive, infra-red heat bulbs are directed toward the assembly at one or more points during or after the process described. When the adhesive has set, the assembly is removed from the mandrel 44, the empty mandrels returnedto the first stage of the assembly process, and the diaphragm voice coil assembly mounted in the speaker basket.

The peripheral flange I4 of the speaker basket I6 supports the rim 46 of the diaphragm 43. A gasket I5 overlies the diaphragm rim, and these elements are adhered together. The remaining assembly process is generally conventional. A pad I3 of felt or the like is adhered to the center of the diaphragm to close the end ofthe coil sleeve 59. The spider I2 is adhered to the speaker basket I6 at 85 to seal the voice coil from dust and dirt. The speaker coil extends into the gap 82 between the pole piece 8| of the magnet and the speaker pot I9. The coil leads III and II are connected to spaced terminals 81 projecting from the speaker basket.

A shoulder 84 on the pole piece is sealed with respect to the speaker pot I9 by a resilient washer 83. This washer, the pad I3, and the spider 12 completely seal the coil when it is in the gap 82. The mounting bracket 86 and insulation plate 89 are additional accessories.

The advantage of the present method of forming speakers lies in the simplicity thereof, the speed with which the speakers may be assembled, and the quality of the voice coils formed. The diaphragms are formed of molded pulp or similar material and are ready for use as supplied. The

rpen nst i 2 :ienmin th sl e ,d i

:by, the same nu1 nera1 (are ,stamped out of paper :the mandrel .44 .during the. entire assembly opera- .tion, the. coilsnare prevented, from distorting as theadhesiverdries.

;.In accordance, withthe I patent statutes, I have described the principles of construction and op- ,eration .of my apparatus, for making radio :speakers, ,and while ,I have endeavored to set .forth-the best. embodiment thereof,.I desire to have itunde'rstood that obviouschanges may be i rnade .within the scopepf the following claims e-without departing from theispirit of my inven- 1.-The method, of connecting a coil to adiaphragm through the use of ajrotatable mandrel,

diaphragm rover: theshoulder, attaching the dia- ;;phragm to the shoulder appl'ying adhesive to a wire,. and wrapping ,said ,wire. about the sleeve without removing said sleeve from it the mandrel to form acoil on saidsleeve.

;8 2. The method ,describedin claimlin which .said flexible material is a strip or paper and said shoulder isformed by wrapping more turns of saidpaperadjacent said one end.

BARTON T. "SETCHELL.

- REFERENCES CITED The following-references are of record inethe file of this patent:

UNITED STATES PATENTS Number Name Date 247,082 Manly et a1. Sept. 13, 1881 366,408 Lange July 12, 1887 862,935 Pfanstiehl Aug. 13, 1907 1,848,433 Pridham Mar.'8, 1932 1,891,404 Engholm Dec.120, 1932 1,923,924 Engholm Aug. 22, 1933 1,935,404 Leopold Nov. 14, 1933 1,936,918 Seabert Nov. 28, 1933 1,956,826 Engholm May 1,1934

, 1, 960,016 Knauf, Jr May 22, 1934 1,994,534 Robinson Mar. 19, 1935 2,207,240 Cornwall July9, 1940 2,207,487 Kirkpatrick July 9, 1940 2,359,249 Scheer Sept.'26, 1944 2,435,093 Mitschrich Jan.127, 1948 2,538,621 Hopkins Jan. 16, 1951

Images