US2459260A

US2459260A - High-frequency electrical bonding apparatus for bonding wide layers of dielectric materials

Info

Publication number: US2459260A
Application number: US499599A
Authority: US
Inventors: George H Brown
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1943-08-23
Filing date: 1943-08-23
Publication date: 1949-01-18
Anticipated expiration: 1966-01-18

Description

Jan. 18, 1949. G H, BROWN 2,459,260

HIGH-FREQUENCY ELERTRICAL BONDING APPARATUS FOR BONDING WIDE LAYERS 0F DIELECTRIC MATERIALS Filed Aug. 23, 1945 2 Sheets-Sheet l II in Ennentor Elli-C3635 H.Bn0wn (Ittorneg Jan. 18, 1949. G. H. BROWN HIGH-FREQUENCY ELEC TRICAL BONDING APPARATUS FOR BONDING WIDE LAYERS OF DIELECTRIC MATERIALS Filed Aug. 23, 1945 2 Sheets-Sheet 2 BEORGFA'IBRO Me 05c,

PHD/0 mw H Patented Jan. 18, 1949 UNITED STATES PATENT OFFICE L George H. Brown, Princeton, N. .J., .assignor to Radio Corporation of America, a corporation of Delaware Application August 23, 1943, Serial No.-499,599

5 Claims.

Thisinvention relates to apparatus for bonding mat'erials' electrically, and more particularly to electronic apparatus for sealing together two or more parts or Players of material at least one of which isithermoplasti'c in nature and isrendered tacky when heated, the present invention being in the nature -of an improvement over that disclosed and claimed in the copending application "of Cyril N. Hoyler, Serial No. 477,478, filed February27, 1:943, and assigned to Radio Corporation of America.

In the aforesaid copending application, there isdisclosed'a-so-icalled electronic bonding or sewing machine which includes a pair of electrodes coupled to a high frequency oscillation generator and between which the parts to be united are passed, In one form of invention therein disclosed, the electrodes are constituted by a pair of rollers mounted 'on parallelshafts which are coupled tothe generator by a suitable transmission line. Practical considerations dictate that the mcunting shafts for the roller electrodes shall'be :of fairly short lengths. In many instances, however, 'it is desirable to *bond together two ormore layers "of iverywide material. If the shafts on which the electroderollers are mounted are to be made long enough to provide a head on the machine "of suflicient length to accommodatevery wide material, the length of the path along :which the high frequency current will pass becomes so great that considerable power is lost at the relativelyihi'gh frequencies at which the machine opera'tes.

The primary object of my present invention is to provide :an improved electronic bonding machine of the type set forth above which will be free from the aforementioned-difficulty.

.Mnre particularly, itfis an :object of .my present inventionv tntprovideran improved electronic bond iratus cf the type set .forth which is simple in uc n'si71'uz:tion, :relatively inexpensive in cost, and

:highlyzemcientin use.

. iln accordance with mypresent invention, 'Ipro- :vide' a work supporting .table having an :opening intowhichextends-soneelectrode. Above thework supporting table,.Izarrangesanzassemblyzwhichinchides a high frequency oscillation generator and a pair of axially aligned electrodes which are insulated from each other and which cooperate, as a unit, with the first mentioned electrode to receive 'therebetween the parts to be bonded. Each of the pair of electrodes is connected by a transmission line to the generator, and the transmission line is preferably made of a length equal to substantially one-quarter of the wavelength at the operating frequency, whereby maximum volt- :age is applied to the work, The two electrodes of .the'unit cooperate with the first mentioned electrode to'provide therebetween a high frequency electric field which produces dielectric losses in the parts to be bonded to thereby heat the same. Preferably, the electrodes all have sufficient mass to conduct away from the outer surfaces of the parts being bonded together the heat developed therein, so that only the inner, contacting regions thereof remain tacky and are caused to adhere toeach other in the manner more fully disclosed and claimed in the above identified copending application of Hoyler.

:In one form of the present invention, the electrodes are all constituted by conductive rollers which may be power driven to advance or feed the work forward therebetween. In another 'modification of this invention, the lower electrode is in the form of an elongated bar or plate,

and the assembly above the work table is mounted 'on suitable track structure or the like for movement along :the length of the lower electrode. This form may be found more expedient where the work is of large area and where it is comparatively difficult to feed it forward.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, as well as additional objects and advantages thereof, will best be understood from the following description of several embodimcnts thereof when read in connection with the accompanying drawings in which Fig. 1 is a front elevation of an electronic bonding apparatus constructed in accordance with my present invention,

Fig. 2 is a fragmentary side elevation thereof showing the relation of the electrode rollers to each other;

.Fig. 3 is a view similar to Fig. 1 but showing a differentform of my. invention, and

Fig. 4 is a view partly in side elevation and partly in section taken on the line IVIV of Fig. 3.

Referring more particularly to the drawing wherein similar reference characters designate corresponding parts throughout, there is shown in Figs. 1 and 2 a work supporting plate i such as a table top or the like which may be either of insulating material or a grounded conductive material and which has an opening 3 therein. Extending into the opening 3 is a conductive roller 5 which constitutes one electrode and which is rotatably carried by a yoke member I. The yoke 1 may be constantly urged in an upward direction by a spring 9 and is preferably connected to ground whereby to ground the roller 5. A motor ll may be coupled to the shaft of the roller 5 to drive the latter if desired.

Suitably mounted above the Work supporting member I is a high frequency oscillation generator I3, such as a vacuum tube oscillator adapted to operate at radio frequencies. A frame suspended from the casing of the oscillator l3 has fixed thereto a motor I? and also rotatably carries a shaft 59 which is coupled to the motor H by the gears 2!. The shaft H! has fixed thereto a pair of pulleys 23 which are connected by belts 25 to a second pair of pulleys 2'! on a lower shaft 29 which is parallel to the shaft or axis of the roller 5 and is disposed in close proximity to the opening 3. The shaft 29 has secured thereto a pair of axially aligned, spaced,

conductive rollers 3| which are insulated from each other by an insulating roller 33, the rollers 3| being also insulated from the shaft 29 and acting as a unit in the manner more fully hereinafter described.

The rollers 3! are connected by means of a transmission line 3 to the oscillator l3. Preferably, the line 34 has a length equal substantially to one-quarter of the wave length at the operating frequency of the generator I3 whereby maximum voltage is applied to the electrodes 3| and 5. As will be clearly seen from Fig. 1, the roller 5 has a width sufiicient to bridge the two rollers 31, and the rollers 3| cooperate, as a unit, with the roller 5 to receive therebetween two layers of dielectric material 35, the overlapping marginal portions of which are to be bonded together. For this purpose, the overlapped portions of the work 35 are fed between the rollers 5 and 3! and constitute the dielectric therebetween so that the electric fields set up between the rollers 3| on the one hand and the roller 5 on the other, which fields are of opposite phase instantaneously, will develop dielectric losses therein to thereby heat the work. The electrodes 5 and 3! are caused to engage the work in response to the pull of the spring 9 on the yoke l in an upward direction, Thus, by reason of the heat developed in the work and the pressure applied thereto by the rollers 5 and 3|, the two layers of the work 35 will be bonded together.

The motor H is employed to drive the rollers 3| at the same peripheral speed as that at which the motor I l drives the roller 5. In this way, the work may be fed forward in a continuous operation. At the same time, since the assembly comprising the oscillator E3, the motor H, the transmission line the electrode rollers 3| and associated parts is mounted above the work table l and the work 35, it is apparent that work of any width may be received by the machine between the coacting rollers 5 and ti. Also, since the transmission line is one-quarter wave length long, maximum voltage is applied to the work and a minimum of power is lost.

In some cases, it may be inexpedient or difiicult to feed the work 35 forward by means of the rollers 5 and 3!, particularly where the work 35 is extremely wide or where it is relatively heavy. In such cases, auxiliary feed rollers (not shown) may be provided to assist the rollers 5 and 3|. Where such an arrangement is impractical or otherwise undesirable, the form of my invention illustrated in Figs. 4 and 5 may be employed. In this form of the invention, the work supporting member or table i is provided with an elongated opening 3a in which is disposed an elongated, conductive bar or plate 511, which is preferably grounded. The frame E5, the motor H, the pulleys 25 and 2'? and the belts 25 of the arrangement shown in Fig. 1 are omitted, instead, the casing of the oscillator 13 may have secured thereto a bracket 3'! provided with a crosspiece 39 and outwardly extending shafts M on which are mounted track wheels 43. The wheels 43 ride on a pair of parallel tracks 45 which extend in parallel relation to the length of the opening 3a and the electrode 5a. The crosspiece 39 is provided with a threaded opening 39a in which is received a feed screw d'l driven by a reversible motor 49 through the gears 5|. The transmission line 34 may be enclosed within a casing 53 from the bottom of which extend the rollers 3! for cooperation with the electrode 5a.

The work 35 may be placed on the supporting member I with the overlapping marginal portions thereof between the stationary electrode 5a and the movable electrodes 3!. A plurality of springs 9a insure engagement of both electrodes with the work therebetween. When. the motor 49 is started, the feed screw 41 is driven to move the assembly comprising the oscillator i3, the transmission line 34 and the rollers 3! along the length of the electrode 5a. As in the case of Fig. 1, the electrode 5a is of a width sufficient to bridge the rollers 3!. If found desirable, there may be used instead of rollers 3! a pair of conductive blocks which are insulated from each other by the insulating member 33 and which can slide along the upper surface of the work. In any case, the overlapping margins of the layers 35 will be bonded or sewn along two parallel paths or seams.

Although I have shown and described but two embodiments of my present invention, it will undoubtedly be apparent to those skilled in the art that many other modifications thereof, as well as changes in those herein described, are possible. I, therefore, desire that my invention shall not be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In electrical apparatus for bonding together a plurality of dielectric parts with the aid of heat, the combination of a work supporting member for supporting said parts, said member having an opening therein, an assembly including (1) a source of high frequency electrical energy, (2) a pair of electrodes cooperating as a unit and electrically insulated from each other, and (3) a transmission line coupling each electrode of said pair to said source, said assembly being mounted above said work supporting member and being so arranged relative thereto that said electrodes are disposed in alignment with and in close proximity to said opening, a third electrode mounted below said work supporting member also in alignment with said opening whereby said unit and said third electrode are arranged in opposed relation and are adapted to receive said parts therebetween, means associated with said electrodes for effecting engagement of said electrodes with said parts, said third electrode bridging said pair of electrodes and cooperating therewith for the establishment therebetween of a high frequency electric field for producing dielectric losses in said parts whereby to heat said parts, and track means above said work supporting member on which said assembly is movably mounted.

2. In electrical apparatus for bonding together a plurality of dielectric parts with the aid of heat, the combination of a work supporting member for supporting said parts, said member having an opening therein, an assembly including (1) a source of high frequency electrical energy, (2) a pair of electrodes cooperating as a unit and electrically insulated from each other, and (3) a transmission line coupling each electrode of said pair to said source, said assembly being mounted above said work supporting member and being so arranged relative thereto that said electrodes are disposed in alignment with and in close proximity to said opening, a third electrode mounted below said work supporting member also in alignment with said opening whereby said unit and said third electrode are arranged in opposed relation and are adapted to receive said parts therebetween, means associated with said electrodes for efiecting engagement of said electrodes with said parts, said third electrode bridging said pair of electrodes and cooperating therewith for the establishment therebetween of a high frequency electric field for producing dielectric losses in said parts whereby to heat said parts, supporting means above said work supporting member, said assembly being movably mounted on said supporting means for movement thereon in predetermined relation to said third electrode, and power means for moving said assembly on said supporting means.

3. In electrical heating apparatus for bonding together a plurality of dielectric parts with the aid of heat, the combination of a work supporting member for supporting said parts, said memher having an elongated opening therein, an assembly including (1) a source of high frequency electrical energy, (2) a pair of electrodes cooperating as a unit and electrically insulated from each other, and (3) a transmission line coupling each electrode of said pair to said source, supporting means disposed above said work supporting member, said assembly being movably mounted on said supporting means and being so arranged thereon that said electrodes are disposed in close proximity to said opening and are constantly maintained in alignment with said opening upon movement of said assembly on said supporting means, a third electrode mounted below said work supporting member also in alignment with said opening whereby said unit and third electrode are arranged in opposed relation and are adapted to receive said parts therebetween, said third electrode extending along substantially the full length of said opening and being of a width suflicient to bridge said pair of electrodes at all times regardless of the position of said assembly in relation to said third elec-- trode, and means associated with said electrodes for eifecting engagement of said electrodes with said work regardless of said position, said third electrode and said pair of electrodes cooperating to set up therebetween a high frequency electric field for producing dielectric losses in said parts whereby to heat said parts.

4. The invention set forth in claim 3 characterized in that said supporting means comprises track structure disposed in parallel relation to the length of said opening, and characterized further in that said assembly also includes a plurality of track wheels resting on said track structure whereby said assembly is suspended from said track structure.

5. The invention set forth in claim 3 characterized in that said supporting means comprises track structure disposed in parallel relation to the length of said opening, characterized further in that said assembly also includes a plurality of track wheels resting on said track structure whereby said assembly is suspended from said track structure, and characterized still further by the addition of power means for moving said assembly along said track structure whereby to cause said assembly to move along the length of said opening to thereby cause said unit to traverse the length of said third electrode.

GEORGE H. BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,172,301 Murray et al Feb. 22, 1916 1,177,726 Sessions Apr. 4, 1916 1,267,480 Von Henke May 28, 1918 1,278,234 Sessions Sept. 10, 1918 1,714,867 Gross May 28, 1929 1,941,543 Puckle Jan. 2, 1934 2,113,714 Stein Apr. 12, 1938 2,266,197 Hansell Dec. 16, 1941 2,298,038 Crandell Oct. 6, 1942 2,322,298 Johnston June 22, 1943 2,324,068 Crandell July 13, 1943 2,343,975 Hosfield Mar. 14, 1944 2,397,615 Mittelmann Apr. 2, 1946 Re. 22,374 Carter Sept. 14, 1943 FOREIGN PATENTS Number Country Date 516,783 Germany Jan. 29, 1931 OTHER REFERENCES Terman, Radio Engineer's Handbook, 1943, McGraw-Hill Book C0,, Inc. New York. Pages 186-188.