US2885852A - Capacitor tube closing and forming machine - Google Patents

Description

y 12,1959 -H. c. KREINICK ET AL 2,885,852

CAPACITOR TUBE CLOSING AND FORMING MACHINE 3 Sheets-Sheet 1 Filed Aug. 27, 1953 d w HQ i? y 1959 H. c. KREQINICK ET AL 2,885,852

CAPACITOR TUBE CLOSING AND FORMING MACHINE Filed Aug. 27, 1953 ,5 SheetsSheet 2 @Meya y 1959 H. c. KREINICK ET AL 2,885,852 CAPACITOR TUBE CLOSING AND FORMING MACHINE Filed Aug. 27, 1953 3 Sheets-Sheet a United States Patent Uihce 2,885,852 CAPACITOR TUBE CLOSING AND FORMING MACHINE Horace C. Kreinick and Sidney Jenkins, Chicago, 11]., assignors to Ajax Condenser Co., Inc., Chicago, Ill., a corporation of Illinois Application August 27, 1953, Serial No. 376,791 11 Claims. (Cl. 53-378) This invention relates generally to apparatus for forming condensers or capacitors and more particularly, is concerned with a novel and unique machine for forming the types of condensers known as paper condensers and electrolytic condensers mounted in tubes, and for closing the ends of the tubes.

In our co-pending application Serial No. 372,458 and filed August 5, 1953, entitled Method of Manufacturing Condensers and Product, now abandoned, it was pointed out that the difiiculties heretofore encountered in the manufacture of paper and electrolytic condensers of the smaller types enclosed in paper tubes and used as components in electrical circuits for radio, television and other electronic equipment gave rise to significant cost advances of the condensers. Therein was disclosed a novel the condenser leads extending outward from the interior of the tube through the closed ends thereof. That invention eliminated the necessity for handling of wax This invention is concerned with a machine for closing oil the ends of the tube and forming the condenser of either type in a continuous operation. The machine is characterized by the relative inexpensive of, the simplicity and ease of operation elimination to obtaining substantial reductions in the final cost of the product, and accordingly, this is a principal object sought by the invention.

Another object of the invention is to provide a condenser forming machine of the character described in which, after the tube containing the condenser section therein and centerin. the conden er leads at the axis of the tube.

Another object of the invention is to provide a machine of the character described having novel means for crimping the ends of the tube preparatory to closing them ofr and novel means operative after the ends of the tube have been crimped to close the crimped ends.

These and other objects of the invention will become apparent as description thereof proceeds, in connection with which a preferred embodiment thereof has been described in the specification in detail and shown in the accompanying drawings. Those minor changes in the size, proportion, arrangement and construction of the various parts of my novel machine which may occur to the artisan skilled in the field of endeavor to which the invention pertains are contemplated as coming within 2,885,852 Patented May 12, 1959 the scope of the invention as defined in the appended claims.

In the drawings wherein the same characters of references are employed to designate similar or equivalent parts of the machine throughout the various figures thereof:

Fig. l is a plan view of a condenser tube closing and forming machine constructed in accordance with the invention, using one form of actuating mechanism.

Figs. 2 and 3, Figs. 4 and 5, Figs. 6 and 7, Figs. 8 and 9, Figs. 10 and 11 and Fig. 12 are views illustrating the tube closing parts of said machine and the progressive steps of operation thereof in forming the condenser and the successive positions of an end of the condenser tube as same is being closed by the machine.

Fig. 13 is a diagrammatical view showing parts of the machine after the condenser has been formed and a manner in which the condenser may be removed therefrom.

Fig. 14 is a side elevational view of the forming jaws of the machine, one of the jaws being shown in section for purposes of illustrating structural details.

Fig. 15 is a sectional view taken through one of the forming jaws along the line 15-15 of Fig. 14 and in the direction indicated.

Fig. 16 is a perspective view of a crimping bar utilized in closing the end of a tube.

Fig. 17 is a sectional view taken along the line 1717 of Fig. 14.

Fig. 18 is a sectional view taken through a modified form of tube closing jaws capable of being employed in the machine.

Fig. 19 is a perspective view of an end of the condenser formed with the modified jaws shown in Fig. 18.

The machine embodying the invention is capable of forming either paper or electrolytic condensers. A paper condenser has been shown in the figures of the drawings. by way of example only, same being designated 20, in Fig. 1. Same includes a condenser section 21 (such as shown in Fig. 2) having pigtails or leads 22 and 23 connected respectively to the foil of the unit 21 as indicated at 24 and 25. The completed condenser has the unit 21 encased in a paper tube 26 with the leads 22 and 23 extending outwardly from the interior of said tube. As explained in said co-pending application, the section 21 must be centered within the tube and the leads 22 and 23 must be aligned with the axis of the said tube.

The machine embodying the invention has been designated generally 30 in Fig. 1. Same may be provided with a suitable mounting platform 31, the particular construction of which is immaterial. The machine includes any means for positioning a tube contining the condenser section, the ends of said tube being open, between the forming jaws of the machine. The jaws then are moved toward each other to close the ends of the tube and automatically properly positioning the condenser section The forming jaws the tube to a predetermined position and pusher means which thereafter close the crimped ends of the tube.

In Figs. 2 through 13, there Figs. 3, 5, 6, 8 through which being closed by the machine. 32' are shown in Figs. 2, 4, 7, 9,

'tend outwardly from the interior of the tube means have been designated-generally 33 and the pusher means have been designated 34.

In Fig. 2, the tube 26 containing a condenser section 21'therein is shown positioned in the machine between the forming jaws 32 and 32'. The leads 22 and 23 ex- 26 through the crimping means 33 and the pusher means 34. Of course, each jaw has the same crimping and pusher means. The jaws 32 and 32 have been moved toward each other so that the ends of tube 26 are received in passageways 35 and 36 respectively in the said jaws. The crimping means 33 and pusher means 34 are spaced from the ends of the tube 26. Nothing has happened yet to the ends of the tube, the appearance thereof being as shown in Fig. 3, entirely open.

The crimping means 33 then move toward each other in the direction of the arrows 37 and 37 respectively converging on the open ends of the tube 26. As shown in Fig. 4, the means 33 have commenced to bear against the ends of the tube crimping same inwardly. The appearance of the tube at this stage is shown in Fig. 5, the end of the tube 26 being crimped slightly inwardly as indicated at 38 along the periphery of tube end. The pusher means 34 still remain spaced from the ends of the tube and the jaws are shown spaced apart a distance less than that shown in Fig. 2.

In Fig. 7, the jaws 32 and 32 have moved together and the crimping means 33 have crimped the ends of the tube 26 to the condition shown at 39 in Fig. 6. The pusher means 34 still remains spaced from the ends of the tube. As shown in Fig. 6, the end of the tube is almost closed about the lead 22.

In Fig. 9, the pusher means 34 then move toward one another in the direction of the arrows 40 and 41 respectively. The crimping means 33 remain in the same position as shown in Fig. 7. The resulting tube in this stage of operation of the machine 30 is seen in Fig. 8 with the end of the tube 26 being just about closed as indicated at 42. Since the position of end of the tube as indicated at 39 is slightly flared outwardly, the action of the pusher means 34 is to push the flared end 39 inward to the condition shown at 42.

In Fig. 10, the pusher means 34 is shown in its final position, having moved completely to close the end of the tube as indicated at 43 in Fig. 11. The end so closed is tightly engaged over the lead 22. The crimping means 33 are still in position against the tube ends.

After the ends of the tube have been closed, the crimping means 33 move away from the tube ends in the direction of the arrows 44 and 45 as shown in Fig. 12. Thereafter, the pusher means 34 move outwardly in the same direction leaving the closed tube suspended from its leads between the jaws as shown in Fig. 13. The dotted line representation 46 of the hand is intended to show that after the crimping means and the pusher means have moved out of engagement with the tube, the closed tube may then be removed. This may either be done manually as shown or suitable mechanical gripping means may be provided for grasping and removing the condenser.

The operation of the machine 20 as described above is continuous and automatic from the time the open-ended tube is positioned therein as shown in Fig. 2 to the time the ends of the tube are closed as shown in Fig. 12 and Fig. 13. Each complete cycle of the machine provides a closed tube in which the condenser unit is accurately centered within the tube and the electrical leads are aligned with the axis of the tube. The operation of the machine is substantially fool-proof and the resulting prodnet is superlative.

Referring now to Figs. 14, 1 5, 16 and 17, the detailed structure of the various means comprising the machine 30 are shown. Considering the jaw members each said member is constructed identically so that only one of them need be described in detail. The right-hand jaw member has been designated 32 for purposesof this de- 4 scription. Same includes a face plate 50 and a block 51 secured to the rear surface thereof by suitable fastening members such as the screws 52 engaged in aligned openings in said plates in a well known manner. The plates may be annular in configuration with the plate 51 having a slightly smaller diameter. For purposes of this invention, the plates 50 and 51 may be considered as one member "and if desired, may be formed in this manner.

The plates 50 and 51 have an axial passageway 35 therethrough. Surrounding the passageway 35 are a plurality of radially extending passageways 55, 56, 57, 58, 59 and 60, each of which communicate from between the passageway 35 to the peripheral edges of the plates 50, 51. The passageways 55 through 60 are arranged circumferentially at equal angles. There is a narrow slot 61 in the plates communicating with one side of the axial passageway 35 and the peripheral edge of the said plates.

Each of said passageways 55 through 60 has an elongate bar 63 engaged therein. Such a bar 63 is shown in Fig. 16, same including a body portion 64 and a narrow blade portion 65 at one end thereof. The leading edge of said portion 65 is indicated at 66 and same is ground at an angle as at 67 toward the point 68 thereof. The body portion 64 may be rectangular in which case the passageways 55 through 60 will also be rectangular.

Each bar 63 is fitted into a said passageway 55 through 60 respectively with the body portion 64 engaged in a said passageway and held by set screws 63' and the blade portion 65 disposed in the axial passageway 35. The portion 64 extending outwardly of the said passageways may be ground down to the face of the peripheral edge of the plate 50 if desired.

The angle edges 67 of the blades 65 are arranged preferably so that same form an angle of approximately fifteen degrees with the plane at right angles to the axis of the jaw movement. It has been found through considerable experimentation that for small condensers using the usual dimensions of paper tubes, i.e., where the condenser is approximately one-half to three-quarters of an inch in diameter, the fifteen degree blade end will produce the most satisfactory closure, utilizing six blades set sixty degrees apart. Success has been achieved with other angles, from substantially less than fifteen degrees to substantially more, but this will be a matter of experiment. We have found that the leading edges of the blade end must be smooth and rounded in order to prevent cutting of the paper ends of the tubes, and the angle of the blade end should be greater than that which crushes the paper itself rather than crimpingly collapses the tube.

Obviously there may be more or less blades, but the closure resulting must have segments forming a sort of rosette, angularly disposed about the circumference of the jaws by equal amounts.

Referring to Fig. 15, the bars 63 are received in the passageways 55 through 60. Each bar 63 is positioned in a said passageway so that the tips 68 thereof define a small circular space 69 at the axis of the passageway 35. The edge 66 of portion 65 of each bar 63 is faced toward the plate 50. The bars 63 thus positioned provide the crimping means 33 referred to above.

The pusher means 34 may best be seen in Figs. 14 and 17. Said means include an elongate rod movable in and out of the plate 50 and 51 in passageway 35, there being such a rod provided for each jaw member 32 and 32. For purposes of illustrations, one such rod has been designated generally 34 in Fig. 14 and same is described. The rod 34' is of circular cross-section and has a diameter slightly smaller than the diameter of the axial passageway 35 so that same may move freely therein. Said rod includes a solid portion 70, the end 71 of said rod having a plurality of radial longitudinally extending slots 72, 73, 74, 72, 73', 74' therein. The slots are arranged equi-angularly about the circumference of the pusher 34' and hence are aligned with the blades 65. Obviously there are the same number of slots as blades. The slots 72 through 74 and 72 through 74' each extend completely through the end 71 so that when the rod 34' is pushed through the passageway 35 the blade portion 65 of each bar 63 will be cleared by the rod 34 by virtue of the slots.

The end also has a single slot 75 extending from the peripheral edge of the rod end to the interior thereof. The rod 34 is positioned so that when same moves in the passageway 35, the slot 75 may be aligned with the slot 61 in the plates 50 and 51. The slots 75 and 61 permit a lead such as 23 to be received in the space 69 between the blade ends 68, this best being shown in Fig. 15.

It will thus be seen that as the jaw member 32' is moved in the direction of the arrow 37', the end of the tube 26 adjacent said member will ride in the passageway 35 since the diameter of said passageway is made slightly larger than the diameter of the tube 26. The bars 63 are carried toward the tube end and the slanted edge 67 of each bar 63 will engage the tube end. The radially aligned edges 67 will press the tube end inwardly as shown in Fig. at 38 forming the crimps in the tube end. Continued movement of the jaw member 32 in the direction of arrow 38 will fold the tube end inwardly to the condition shown at 39 in Fig. 6.

When the pusher rods are moved toward one another, they will clear the blade portions 65 by reason of the advantageously placed radial passageways in said pusher rods. The end of the rod then bears against a crimped end of the tube 26 closing same in the manner shown in Fig. 11 at 43. It is emphasized that the operation of the machine automatically centers the condenser unit in the tube 26 and properly aligns the leads 22 and 23 relative to the axis of said tube.

It is desired that the machine operate in cycles automatically. In other words, after the tube with open ends is positioned in the machine said ends are closed in the manner desired by the sequential movement of the jaw means 32 and 32', the crimping means 33 and pusher means 34- automatically to complete a cycle of operation of the machine. To accomplish this, a construction such as shown in Fig. 1 may be provided.

In Fig. 1, the condenser 20 is shown positioned in the machine with the leads 22 and 23 positioned in the manner described above. On one side of the condenser is mounted a gear wheel 89 on spindle 81 while on the opposite side is mounted a similar wheel 82 on the spindle 83. Said spindles 81 and 83 may be operatively connected to a source driving the same, such as a motor or other well known apparatus.

To the plates 51 of the jaw members are secured L- shaped arms 34 and 84 by means of a conventional screw 35 such as shown in Fig. 14, the ends of arms being shaped to permit same to engage over the plate 51. other legs 86 and 36 have toothed racks 87 and 87' on the upper and inner respective surfaces thereof which mesh with the gear teeth of the wheel 82. It will be noted that the arm 84 of the L-shaped lever positioned to the left of the condenser 20 in Fig. 1 is longer than the arm 34 of the right hand lever so that the racks 87 and 87 of each arm will engage the wheel '82 on diametrically opposed points thereon. Thus rotation of the wheel 82 will move the plates 50 and 51 of each jaw member either toward or away one from the other de pending on the direction said wheel 82 is rotated. Obviously, the bar members 63 will move with the respective jaw member. Likewise movement of one jaw member will cause identical but opposed movement of the other jaw member.

A similar construction is employed for moving the rods 70. An L-shaped lever 90 has one leg thereof secured to one of the rods 70 by means of a set screw 91, the other leg 92 thereof having a rack 93 engaged with the teeth of the gear wheel 80. Another L-shaped lever 94 has one leg thereof secured to the other rod 70 by a screw fastener 95, the other leg 96 thereof also having a rack 97 engaged with the teeth of wheel 80. The levers and 94 are constructed so that the legs 92 and 96 respectively thereof will be arranged on opposite sides of the wheel 80. Rotation of the wheel or movement of one lever will move both levers 90 and 94 simultaneously so that the rods may be moved toward or away one from the other.

It should be appreciated that the machine illustrated in Fig. 1 is a very crude form of the actual mechanism which may be used to practise the invention. The principal features of the invention lie in the structure of the various moving parts of the machine which form the capacitor. The connected mechanism for properly cycling the machine is a matter of choice.

Thus, through suitable linkages, from the condition as seen in Fig. l, first the gear 82 is driven in a counterclockwise direction. As it completes a full revolution of its movement, and even before, the gear 80 is driven in a clockwise direction bringing up the pushers to close off the ends of the formed tube. Just at about the time the pushers have completely closed the tube, the gear 82 may be reversed Withdrawing the forming jaws to their full extent. ter the tube is closed the pushers may be withdrawn through reverse rotation of the gear 80 just a sutlicient amount to enable some grasping means to pull the completed condenser out of the machine. The sequence of rotation of the gears may be accomplished by any of a large number of well known linkages.

In another mechanical arrangement for driving the pushers and jaws, suitable cams may be utilized to provide the proper cycle. In the diagrammatic representation in Fig. 1 there have been illustrated a pair of cams, 191 and 102 controlling respectively the movement of the forming jaws and pushers. The cam 101 is rotated in synchronism with cam 162 as indicated by the broken line 103. A groove 164 is formed on the cam 101 whose contours are such as to give the desired movement of the forming jaws 32 and 32. A follower 105 is carried by the link 106 which is connected at 107 to the arm 84. In like manner the cam 102 has a groove 110 carrying the follower 112 of the link 113 connected at 114 to the lever 90 to operate the pushers.

The mechanism enables the proper cycling to be simply adjusted in accordance with the predetermined contours of the cam grooves 104 and 110.

thickness of the rosette protects the connection between the leads and the section, and the overall size of the condenser is greatly reduced over prior structures.

Through the teachings of the invention it is a simple matter to provide a machine which through a simple cycle of mechanical movements and the use of the structure described is able to increase the rate of manufacture of this type of capacitor and decrease the cost of manufacturing the same.

It is important to emphasize that the final product which has been achieved through the teachings of the invention has its pig-tails not only centered but seized in the apices of the segments of the rosette. This is best illustrated in Fig. 11. The end of the condenser thus formed is flat. It may be required to assure the closure or" the ends of the condenser, for example where the 7 same will be used at very low. pressures, or it may be essential to have a larger length of the leads engaged by the condenser ends than is illustrated in Fig. 11. Accordingly the parts of the structure may be varied to provide for these requirements.

Thus in Fig. 18 l have illustrated a modified form of the invention in which the structure is identical in every respect with that heretofore described except that the circle formed by the ends 68 of the blade members 65 is slightly larger than in the previous case. Because of this, the formed tube will have a protrusion or teat 120 on the end integrally formed with the end rosette and having the leads protruding from the center thereof. The pusher will further this protrusion 120 upon the lead thereby providing a tightly closed end for the condenser.

The condenser 121 is shown having leads 122 and 123 disposed in the identical apparatus described. The bar members 126 have their blade portions 127 spaced about the axes of the passageways 35 and 36 a greater distance than in the previously described structure to permit the formation of the protrusion 120. The angle of the leading edges equivalent to the portions 67 of Fig. 16 may be determined through experimentation, although 150 or thereabouts has been found satisfactory for the modified form of the invention as well.

One important feature of the invention, namely the wedging of the segments against the condenser leads has been emphasized in the modified form of Figs. 18 and 19.

It is believed that the invention has been described in sufficient detail to enable the skilled artisan to practice the same. Although a preferred embodiment of the invention has been shown and described in detail, it is desired to avoid being limited to the precise arrangement, construction, size and proportion of the various parts thereof except as defined in the claims hereto appended.

We claim:

1. In a condenser forming apparatus for closing ofl" the ends of a tubular member, there being a condenser section disposed in the member with an electrical lead extending out through the opening thereof, a forming jaw having a central passageway, a plurality of blades equally spaced about the said jaw and each having an end disposed in the passageway in a plane passing through the axis of the passageway, the said jaw adapted to be moved relative to said flexible tube to crimp the end thereof, the leading edges of the said blades being slanted inwardly and radially in the direction of movement of the said flexible tube member end against the said blades whereby the edges of the tube end will be collapsed by the said blades and a pusher member adapted to pass through the said passageway and engage against the end of the said tubular member after the same has been closed to press the collapsed end into a flat formation with the lead extending out the center thereof, the said pusher member having a plurality of radial slots aligned with the said blades whereby freely to move through the said passageway without interference with said blades.

2. A structure of the character described which comprises a pair formation, having a central passageway therethrougb. each jaw member having a plurality of equally spaced radially inwardly extending blades in the said passageways, means for moving the said jaws together for segmentally collapsing the ends of a flexible tube member disposed in the said passageway, and means operable after the said jaws have moved together and collapsed the said ends to press on the said ends to flatten and lock the said ends.

3. A structure of the character described for closing off the ends of a capacitor, the said capacitor prior to having its ends closed consisting of a capacitor section loosely disposed within an open ended cylindrical tube of flexible material substantially longer than said section with electrical leads of the section protruding outwardly through the open ends of the cylindrical tube;

comprising, a pair of axially aligned chuck members mounted for axial movement toward and away from one another and each having a coaxial passageway for enabling sliding movement of the tube therein, each chuck having a set of equi-circumferentially spaced blades extending radially into the respective passageways, the blade tips of each set defining a small circle coaxial with the respectvie chuck members, the blade edges of one set facing those of the other set and being slanted radially inward in a direction receding from the other set, means for moving the chuck members toward one another a distance to bring the blades closer together than the length of the tube but not as close as the length of said section, whereby to segmentally collapse the tube ends, thereby centering the section in the tube and axially centering the leads in the collapsed tube ends.

4. The structure of claim 3 in which each of the chuck members has an elongate radial slot, the slots being aligned, to enable the leads of the capacitor to be passed into or out of the chuck members to the centers thereof without bending. 5. A structure of the character described for closing ofl the ends of a capacitor, the said capacitor prior to having its ends closed off consisting of a capacitor section loosely disposed within an open ended cylindrical tube of flexible material substantially longer than said section with electrical leads of the section protruding outwardly through the open ends of the cylindrical tube; compris- 1 ing, a pair of axially aligned chuck members mounted of jaw members, each of generally circular for axial movement toward and away from one another and each having a coaxial passageway for enabling sliding movement of the tube therein, each chuck having a set of equi-circumferentially spaced blades extending radially into the respective passageways, the blade tips of each set defining a small circle coaxial with the respective chuck members, the blade edges of one set facing those of the other set and being slanted radially inward in a direction receding from the other set, means for moving the chuck members toward one another a distance to bring the blades closer together than the length of the tube but not as close as the length of said section, whereby to segmentally collapse the tube ends, thereby centering the section in the tube and axially centering the leads in the collapsed tube ends, a flat ended piston in each chuck adapted for free movement in the respective passageways, and means for moving the pistons inwardly or outwardly in unison, the said pistons adapted to be moved against the collapsed tube ends to press same into locking engagement upon the respective leads.

6. A structure as described in claim 5 in which each piston has a central axial passageway for accommodation of said leads.

7. A structure as described in claim 5 in which each piston has a central axial passageway for accommodation of said leads and a plurality of radial longitudinally extending slots terminating short of the central axial passageway and aligned with and clearing the blades of the respective chuck member to permit free movement of the said pistons in said passageways.

8. A structure as described in claim 7 in which each piston has an additional radial longitudinally extending slot communicating with the central axial passageway of the piston to enable the leads of the condenser section to pass freely into the central axial passageway of the piston without bending.

9. A structure as described in claim 4- in which each chuck member has, in addition, a flat-ended pusher member provided with a central axial passageway for accommodating the leads and with a plurality of radially extending slots for clearing the blades, means for moving the pusher members against the collapsed tube ends while the same are still engaged by the blades, the slots in the pusher members permitting the chuck members to be separated leaving the formed capacitor secured between the pusher members.

10. A structure as described in claim 4 in which each chuck member has, in addition, a flat-ended pusher member provided with a central axial passageway for accommodating the leads and with a plurality of radially extending slots for clearing the blades, means for moving the pusher members against the collapsed tube ends while the same are still engaged by the blades, the slots in the pusher members permitting the dhuck members to be separated leaving the formed capacitor secured between the pusher members, and each pusher member has a radial longitudinally extending slot communicating with the central axial passageway whereby the finished product may be removed from between the pusher members Without bending the leads or separating the pusher members from physical cont-act with the said collapsed tube ends.

11. A condenser forming machine which is adapted tightly to close oil the ends of a flexible tube of cylindricall formation having a capacitor section therein provided on opposite ends thereof with leads extending out the open ends of the tube before same are closed off and extending out of the center of the closed off ends, which comprises, a standard, a pair of chuck members coaxially mounted on said standard and movable toward and away from one another, blade means in each chuck member arranged equi-circumferentially and extending toward but terminating just short of the axes of the respective chuck members, said blade means of each chuck member presenting inwardly extending edges slanting away from the blade means of the other chuck member, slot means for enabling an unformed condenser to be disposed in the machine with its ends accommodated in the respective chuck members and its leads extending outward coaxially of the chuck members, a pusher member in each chuck for coaxial movement relative thereto and having radial slots for clearing the blade means and slot means for clearing the leads, chuck member driving means, and pusher member driving means, and a mechanical connection therebetween to drive the same in syndhronism, with the chuck members moving together to crimp the tube ends with the blade means, after which the pusher members move together to flatten the tube ends, following which the chuck members separate.

References Cited in the file of this patent UNITED STATES PATENTS 1,764,247 Ducart June 17, 1930 2,375,144 Stephano et al. May 1, 1945 2,627,538 Brennan Feb. 3, 1953 2,665,329 Brennan Jan. 5, 1954 FOREIGN PATENTS 17,974 Australia Jan. 22, 1929 145,875 Australia Mar. 25, 1952

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