US2393718A - Material forming apparatus - Google Patents

Description

' Jan. 29, 1946. r

0. STENSON ERAL MATERIAL FORMING APPARATUS Z SheetS-Sheet 1 Filed June 10, 1944 m h. g

Jan. 29, 1946.

0. STENSON ET AL MATERIAL FORMING APPARATUS Filed June 10, 1944 2 Sheets-Sheet 2 Patented Jan. 29, 1946 MATERIAL FORMING APPARATUS Olaf Stenson, Chicago, andRalph A. Vinson,-Naperville, lll., assignors to Western Electric Company, Incorporated, New York, N. Y., a corporation of. New York Application June 10, 1944, Serial'No. 539,770

4 Claims.

This invention relates to material forming apparatus and more particularly to an apparatus for hot forming the leads on a stem of a vacuum tube.

Vacuum tubes usually include a glass supporting stem having a plurality of leads extending therefrom for the purpose of supplying electrical energy to the completed tube; In certain types of tubes, two composite leads are used wherein a portion of each lead is of tungsten wire or the like and the two tungsten portions are similarly double bent or ofiset away from inner parallel portions thereof at points predetermined distances from their outer ends and then inwardly toward each other to provide parallel spaced outer ends. Due to the hardness of the tungsten portions, the close spacing thereof on the glass support, and the required forming thereof to accurate dimensions, the manufacture of such leads is a difiicult operation.

An object of the present invention is the provision of a simple and effective apparatus for efllciently and accurately hot forming tungsten leads on a stem of a vacuum tube.

In accordance with the above object, the present invention, in one embodiment thereof as applied to the hot forming of the above-described type of vacuum tube leads, comprises two sets of longitudinally spaced normally aligned and laterally spaced jaws for receiving therebetween one lead at a time to be formed. Means is provided for moving one jaw of each set toward its companion jaw to grip the lead therebetween and thereafter to move and offset one set of jaws as a unit laterally relative to the other set of jaws, which remain stationary, which latter movement forms the required double bend in the lead, the inner and outer portions of the lead adjoining the points of bending being parallel. One jaw of each set and the tungsten lead, after being gripped by the cooperating jaws and upon the closin of a control switch, are included in a suitable electric circuit which heats the tungsten lead to increase its plasticity prior to the bending operations.

Other objects and advantages of this invention will more fully appear from the following detailed description taken in conjunction with the accompanylng drawings, in which Fig. 1 is a fragmentary plan view of a vacuum tube lead forming apparatus embodying the features of the invention and showing the apparatus in operative position after completion of the forming of one lead;

Fig. 2 is a view similarto and of a portion of Fig. 1 illustrating the normalposition of the jaws and operating parts of the apparatus with one of the leads in position between the sets of jaws ready to be formed;

Fig. 3 is a plan view of a vacuum tube stem with the leads formed thereon by the apparatus of this invention;

Fig. 4 is a transverse vertical section taken on line 44 of Fig. 1 and diagrammatically illustrating the circuit for electrically heating the tungsten leads; and

Figs. 5 and 6 are longitudinally vertical .sections'taken on lines 5-5 and 6--6, respectively, of Fig. 1.

Referring to'the drawings in detail and particularly to Fig. 3, a glass supporting stem of a vacuum tube is indicated at NJ, in which are fused two spaced composite lead wires II and I2 having inner and outer portions (3 of copper and intermediate portions [4 of tungsten. The leads are straight and extend from the left end of the stem In (Fig. 3) for a desired length at the time the stem is'mounted upon the forming apparatus, as shown in Fig. 2, to effect the desired double bending operations on one lead at a time, as shown in Fig. 1,, wherein the tungsten portion M has been bent at two points I! and I8 to provide a greater spacing between parallel outer copper portion [3 of the leads H and I2.

The lead forming apparatus comprises a steel base plate 20 having a reduced thickness at its right side (Fig. 4). Suitably fixed to the upper face of the reduced portion and also to the bottom face of the plate 20 are fibre insulator sheets 2| and 22. A stationary copper block 23 is mounted upon and secured to the sheet 22 and the plate being movable parallel to the block 23. Attached to the upper face of the plate 201s a steel block 30, upon which is mounted an irregular shaped steel plate 3 l, the block'and plate being secured to the base plate 20' by screws 33. The plate 3| extends acrossv the upper face of the slidable copper block 29' and has sliding engagement therewith. Also in slidable. engagement are the adjacent vertical facesof the blocks 29 and 30'. For the purpose of guiding the block'29'in its sliding movements, pins 34 and 35' extend from the upper face thereof and into slots 36 formed in the plate 3!, the pins having opposite parallel fiat guide faces abutting similar faces of'the slots.

Attached to the vertical right end faces of the copper blocks 23 and 29, for a purpose which will be made obvious hereinafter, are steel wear or thrust plates 31 and 38, respectively. Slidable in counterbored apertures 41 in the copper blocks 23 and 29 are rods 42, each having a jaw head 43 secured to a screw threaded reduced end thereof by nuts 44, the opposite ends of the rods being eye-shaped and pivotally connected to each is a bifurcated cam lever 45 having cam faces 48 formed on the furcations thereof which constantly engage the thrust plates 31 and 38. Surrounding each of the rods 42 within the enlarged diameter of the apertures 41 is a compression spring 49 bearing at opposite ends against the inner face of the thrust plate and a pin 59 fixed to the rod. The normal action of the springs 49, when the cam levers 45 are rocked to a vertical position, shown in broken outline in Fig. 6, is to slide the rods and the attached jaw heads 43 to the left, as viewed in Figs. 1, 2, and 6. When the cam levers 45 are rocked clockwise to the position shown in full lines in Figs. 1, 5 and 6, the rods 42 with the attached jaw heads 43 are drawn to the right. In order to maintain the jaw heads 43 in desired vertical positions (Fig. 4), horizontal guide pins 5| are fixed to the copper blocks 23 and 29, which are slidably fitted in apertures in the jaw heads.

Tungsten jaw face plates 55 are fixed by screws 56 (Fig. 6) to the opposed vertical faces of the jaw heads 43 and thecopper blocks 23 and 29, thus providing two sets of laterally spaced jaws, the jaws of each set being normally aligned and open, as shown in Fig. 2. The copper block 29, which, as hereinbefore described, is longitudinally slidable, is provided at its left end (Figs. 1, 2 and 6) with an arm 51, the outer end face of which is constantly maintained in engagement with a cam lever 58 having a cam face 59 under the influence of a tension spring 60 having its opposite end fixed to a pin 62 carried by the stationary plate 3| and to the guide pin 35 fixed to the copper block. A pivotal mounting for the cam lever 58 on the base plate 20 is indicated at 53 and the lever is equipped with a handle 64. With this arrangement and the cam lever 58 rocked to the position shown in Fig. 2 in full lines and in Fig. 1 in broken lines, the two sets of jaws 55 will be aligned as shown in Fig. 2, providing the cam levers 45 are in their vertical position, as shown in broken outline in Fig. 6. A stop pin 65 carried by the base plate 20 serves to limit the clockwise movement of the cam lever 58 about its pivot 63. The movement of the copper block 29 towards the right (Fig. 1) is limited by an adjustable stop pin 68 mounted on the base plate 20, which engages the thrust plate 38. Upon the cam lever 59 being rocked counter-clockwise from its full line position (Fig. 2) to its full line position (Fig. 1) or to any point intermediate the two illustrated positions of the lever, as limited by the adjustable stop pin 68, it will be apparent that the copper block 29 will be moved to the right, carrying with it the associated jaw face plates 55, thus offsetting them relative to the jaw face plates 55 carried on the stationary copper block 23.

Each of the jaw face plates 55 is similar in structure for facilitating their mountings on the jaw heads 43 so that the following description applies to each of them. As clearly shown in Figs. 5 and 6, the inner opposed vertical side faces ofv the jaw 55 of each set are stepped, as indicated at 69, thus providing a greater thickness thereto at their upper endsand the portions of greater thickness are semi-circularly grooved to a suitable dimension at 10 across the entire width of the jaws, the grooves being in horizontal alignment, so that when the tungsten portions M of the leads I l and 12 are entered therebetween and spanning the space between the two sets of jaws and then clamped in a manner to be presently described, they will be firmly held with a slight clearance between the adjacent opposed ungrooved upper jaw faces at each side of the grooves. To facilitate the positioning of the tungsten portion [4 of the leads II and I2 between the jaw faces at the desired position for forming, the upper end faces of the jaw faces are similarly notched at H, so that the operator merely aligns the outer end of the tungsten lead portion where it joins the outer copper lead portion I3 with the right hand notches in the jaws associated with the slidable copper block 29 (Fig. 4) and the lead is in position for forming at the desired point. Opposite vertical end faces of the jaw plates 55 are notched at 12 at their upper ends for the accommodation of slight variations in the length of the glass stems 10.

As hereinbefore stated, the tungsten lead portion I4 is heated to increase its plasticity prior to the shaping thereof by its inclusion in a suitable electric circuit shown diagrammatically in Fig. 6. Such a circuit is of suitable low resistance and heavy current carrying capacity, the amperage of the current carried by the circuit depending upon the size of the tungsten lead portions [4 and the amount of heat desired. This circuit includes a secondar winding 15 of a transformer T6, the terminals of which are wired by means of heavy fiexible copper leads 1'! and 18 to the copper blocks 23 and 29, respectively, to which one jaw face plate 55 of each set of jaws is attached. The leads '1'! and 19 extend upwardly through suitably dimensioned slots 19 in the base plate 20 and are attached to the copper blocks 23 and 29 by screws 92. A primary winding 83 of the transformer 16 is adjustable so that the amount of current flowing in the secondary circuit may be readily controlled by primary coil adjustment and the primary coil 83 is connected by conductors to a suitable source of power, such as a generator 84. One lead to the primary coil includes a switch 85 for controlling the period during which heat is applied to the tungsten lead portion [4.

In the operation of the apparatus to form the double bend in the tungsten portions M of the leads II and I2, one lead at a time, the lead to be bent is positioned b the operator with one hand between the two open sets of aligned jaws 55 and in alignment with the opposed grooves 10 thereof and also correctly positioned longitudinally relative to the indicating notch 1|, all as shown in Fig. 2. With the lead thus positioned, the operator, with his other hand, rocks the two cam levers 45 clockwise from their broken outline position (Fig. 6) to the full line position thereof (Figs. 1, 5 and 6) which, in the manner previously described, closes the jaw face plates 55 upon the lead. This is followed by the operator closing the switch (Fig. 4), thereb causing a flow of current through the secondary winding 15 of the transformer I6, which includes the tungsten lead portion (4 held between and by the laterally spaced sets of jaws 55 and it becomes heated and sufficiently plastic for the forming operation which follows immediately and the switch is then opened. This forming operation is effected by rocking the cam lever 58 counterclockwise from its broken outline position (Fig. 1) to the full line position thereof, same figure, and also Fig. 6. In the manner previously described, the copper block 29 carrying one set of closed jaws 55 is moved to the right to the position shown in Figs. 1 and 6, which movement is predeterminedly limited by the adjustable stop pin 68 lying in its path. The lead is thus formed as shown in Figs. 1 and 3. Thereafter, the cam levers 45 are rocked counter-clockwise to their normal broken outline position (Fig. 6), which opens the laws 55 and the stem In with the formed lead is removed and then the cam lever 58 is rocked clockwise from the full line position to its broken outline normal position (Fig. 1) and the copper block 29, under the influence of the spring 60, draws the block to the left to again align the two sets of jaws 55 (Fig. 2), the constant engagement of the arm 51 of the block limiting the latter movement of the block. The second lead fused to the stem I is then formed in a manner similar to that of the lead just described after rotating the stem l0 180 and positioning the lead between the jaws 55.

What is claimed is:

1. An apparatus for hot forming tungsten leads on the stem of a vacuum tube comprising two sets of jaws normally aligned for clamping a lead at spaced longitudinal points, means for constantly urging one jaw of each set to an open position, means for actuating said jaws to clamp the lead, means for mounting one set of jaws for movement as a unit at right angles to the axis of the lead to produce a bend in the lead, means for constantly urging said one set of jaws into normal alignment with the companion set of jaws, means for actuating said one set of jaws to bend the lead, and means for electrically heating the portion of the lead extending between the two sets of jaws to increase its plasticit prior to the bending operation.

2. An apparatus for hot forming tungsten leads on the stem of a vacuum tube comprising a plurality of sets of jaws arranged for clamping a lead at spaced longitudinal points, means including a spring operatively connected to one jaw of each set for urging them in one direction, means for actuating said jaws in an opposite direction, means for mounting one set of jaws for movement as a unit at right angles to the axis of the lead to produce a bend in the lead, means including a spring operatively connected to said one set of jaws for urging them in one direction, means for actuating said one set of jaws in an opposite direction, and an electrical circuit including a control switch, said sets of jaws and the clamped lead for heating the lead to increase its plasticity prior to the bending operation.

3. An apparatus for hot forming tungsten leads on the stem of a vacuum tube comprising two sets of normall longitudinally aligned and spaced jaws arranged for clamping a lead at spaced longitudinal points, means for mounting one jaw of each set for movement to and from its companion jaw, means including pivotal cam levers for actuating "said jaws, means for mounting one set of jaws for movement as a unit at right angles to the axis of the lead to produce a bend in the lead, means for actuating said one set of jaws, and an electrical circuit including a control switch, said sets of jaws and the clamped lead for heating the lead to increase its plasticity prior to the bending operation.

4. An apparatus for hot forming tungsten leads on the stem of a vacuum tube comprising two sets of normally longitudinally aligned and spaced jaws arranged for clamping a lead at spaced longitudinal points, spaced blocks to which one jaw of each set is fixed, one block being fixed and the other slidably mounted for movement at right angles to the axis of the lead, means slidable on said blocks for mounting the other jaw of each set for movement to and from its companion jaw, means for constantly urging each of said other jaws to an open position, means for actuating said latter jaws to clamp the lead, means for constantly urging said slidable block in one direction to align the set of jaws thereon with the companion set of jaws, a pivotal cam lever operatively engaging said slidable block for actuating the same and thereby move the set of jaws thereon out of alignment with the companion set of jaws to bend the lead, and an electrical circuit including a control switch, said blocks and jaws fixed thereto and the clamped lead for heating the portion of the lead extending between the sets of jaws to' increase its plasticity prior to the bending operation.

OLAF STENSON. RALPH A. VINSON.

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