US2069879A - Positive carbon feeding head - Google Patents

Description

Feb. 9, 1937. c FUCHS ET AL 2,069,879

Filed April 6, 1934 Q 0 2 MNZENBRS i f Patented Feb. 9, 1937 UNITED STATES PATENT OFFICE POSITIVE CARBON FEEDING HEAD Application April 6, 1934, Serial No. 719,284

2 Claims.

This invention relates to devices such as positive carbon feeding heads, used as in motion picture machines.

One object of the invention is to provide a device of the character described having improved means whereby a maximum length of a carbon stick can be utilized, for superior economy.

Another object is the provision of a device of the nature set forth, having improved heat shielding and/or dissipating means so that the device is protected from the heat.

Another object of the invention is to furnish a device of the type mentioned having improved means for supplying electric current to the carbon.

A further object of the invention is to provide a device of the class alluded to having relatively few and simple parts, and having features of easy replaceability, and which is durable, reliable, compact, inexpensive to manufacture, and efiicient to a high degree in use.

Heretofore, in devices of this character, considerable waste of the carbon sticks has occurred by reason of the inherent construction of the feeding head. The conventional length of the carbon sticks for the are light is approximately 18 inches, and a standard length of a motion picture reel requires that approximately 5 inches of each of the positive and negative carbon electrodes shall be consumed during the showing of the reel. Nevertheless, a carbon stick could be used for only 2 reels, so that approximately 7 to 8 inches of each carbon stick was wasted. This was due to the fact that the feeding heads at present in use require that approximately 4 inches of the carbon stick shall be maintained therein to permit feeding of the stick, and the difference of 3 to 4 inches is insufficient for a full reel, and during the showing of the picture the reel cannot be stopped to replace the carbon. Hence considerable wastage of the carbon has consistently occurred. By this invention, the feeding head is so rearranged and coordinated that a portion of a carbon stick only 2 inches in length need be maintained therein, and therefore the carbon stick can be used for three reels.

Then again, in the prior art devices, fusion and hence distortion of a portion of the feeding head would occur due to the heat from the are light, and this would interfere with or prevent the feed of the carbon stick. Such heat would also increase the temperature at the electrode connection, and hence the electrical resistance thereat, which in turn would cause additional heating of the feeder head. These and other difficulties have been overcome by the invention hereinafter described in detail.

Other objects and advantages of the invention will become apparent as the specification proceeds.

With the aforesaid objects in view, the invention consists in the novel combinations and arrangements of parts hereinafter described in their preferred embodiments, pointed out in the subjoined claims, and illustrated in the annexed drawing, wherein like parts are designated by the same reference characters throughout the several views.

In the drawing:

Figure 1 is a view in side elevation with parts removed showing a device embodying the invention.

Fig. 2 is a top plan view thereof.

Fig. 3 is a vertical sectional view taken on the line 3--3 of Fig. 1.

Fig. 4 is a perspective view of the shield.

Fig. 5 is a front view of a modified shield.

Fig. 6 is a top plan view thereof.

The advantages of the invention as here outlined are best realized when all of its features and instrumentalities are combined in one and the same structure, but, useful devices may be produced embodying less than the whole.

It will be obvious to those skilled in the art to which the invention appertains, that the same may be incorporated in several different constructions. The accompanying drawing, therefore, is submitted merely as showing the preferred exemplification of the invention.

Referring in detail to the drawing, l denotes a device such as a carbon feeding head for an electric are light of a motion picture machine embodying the invention. The same may include a conventional hollow base or supporting frame II which may include therein a suitable main drive, not shown. The flange IQ of the wall I 4 of said frame has an opening 34 for the carbon electrode 32.

Secured to the front wall l4 of the frame, specifically to the flange l9 thereof, is an angle member 45 including a vertical arm or flange and a horizontal arm 50. The vertical arm is of the same shape as the wall I9 and is directly removably secured thereto by screws Said arm 49 may have a central opening 52 for the carbon stick, and bearings "53 for the shafts 23 and 2! of the respective knurled feed rollers 30, 3|. The bearings 53 may have special hardened antifriction collars 54, and the bearings 53 together with the bearings 22 afford a large bearing area for the shafts adjacent to the rollers. The latter are disposed at the extreme ends of the shafts 23 and 2's in close proximity to the arm of the angle member dB and above the arm 50. The bracket arm 38 for the idler roller 36 is offset horizontally frontward so as to bring the idler roller 36 into the required juxtaposition to the feed rollers. The idler may or may not be knurled, as desired, and may be mounted on shaft 3'! journaled in the ears 35 of the arm 55, the latter being swingably mounted at ll on frame I l for automatic yielding movement of the idler toward the feed rollers.

It may be noted that the shafts 23 and 27 are arranged so that their axes intersect in a horizontal plane, and are rotated by the said main drive at the same speed but in opposite directions.

Mounted on the arm 5 is a refractory angle member 55. The same may be made of a material such as carborundum suitably pressed and heat treated to provide a relatively infusible and extremely strong one piece member. Fire clay, aluminum oxide and zirconium oxide may also be used as refractory material. While certain metals such as Monel metal may be regarded as refractory since they possess extremely high melting points, nevertheless it is preferred to use a non-metallic material whose heat conductivity is necessarily less and which therefore more effectively functions as a heat shield.

The member 55 may include a vertical shield portion 56 forward of the rollers 30, 3|, and having a lower angle portion 51 removably secured to the member 59 as by screws 58. The element 56 may be shaped to generally correspond and baffie the adjacent portions of the device and may have a central opening 59 for the passage of the carbon stick, and also a measuring projection 60 to indicate the required location of the electric are as between the positive carbon stick 32, and the negative carbon stick 6!, the front face of said element 56 is desirably convexed, as shown, to dissipate heat.

Intermediate of the shield 56 and the feeding rollers is a conventional electrode connection 62 for the carbon stick 32. The connection 62 may include upper and lower jaws 63, B4, interengaged by a guide pin 62a, and the former mounted on a rod 65 and the latter on a sleeve 66 taking around the rod. Arms 57 projecting from the rod and'sleeve maybe actuated apart by an expansion coil spring $8 retained by screws 69 and acting to force the jaws 53. 54 together for slidingly engaging around the carbon stick. It will be noted that the rod and sleeve 65, 66 are laterally offset at an end of the jaws 63, 64, to clear the element 57.

Electrical current may be furnished to the electrode connection as at l, the arms 61 being desirably interconnected by a flexible conductor H at the screws 69 and an additional flexible conductor '52 extending from H into direct connection at T3 with the removable support 50, so the current can also pass to the carbon through the rollers.

In Figs. 5 and 6 is shown a modification of the invention, including a shield unit 14, which is similar to the member 55, but is horizontally elongated to afford end projections 15 extending beyond the adjacent parts of the device for radiating the heat thereof into the atmosphere. The front face of the shield may also be vertically grooved to provide fins 16 for dissipating said heat.

In operation, the idler roller 36 is swung outward to permit insertion of the carbon stick 32,

aocasvo after which the idler is released. The forward end of the carbon is placed according to the measuring element 56. The carbon stick 32 is advanced, and simultaneously the carbon stick Si is advanced at the same speed by an independent unit, not shown, so that the arc may be positioned in proper relation to the projector unit. The electric current may then be switched on, and as the entire head i t may be conductive thereto, the casing it bein desirably insulatingly mounted.

It will be seen that the electrode connection 62 is relatively close to the are thereby reducing to a practical minimum the resistance caused by the carbon stick. By also supplying current to the latter through the rollers 39, 3! and 36, the current flowing through member 49, 5'and thence through the shafts 23, 2 and 3?, a substantially greater are-a of electrical contact is afforded, so that contact heat and resistance is reduced. Hence the electrode connection 62 may be made relatively narrow, permitting bringing the rollers as far forward as possible for maximum feed of the carbon stick. Furthermore, if the electrode connection should for any reason fail, current may be temporarily supplied through the rollers. The latter, with their knurled surfaces, afford a very good contact with the carbon, but as the electrode connection extends completely around the carbon, it provides a much greater area of contact than the practically tangent contacts of the rollers. Thus while the latter may be used as a supplemental electrical feeder means, it is undesirable to utilize them as the electrode connection, because of the excessive resistance and heat that would result with consequent greater wear on the rollers, when a large current is used.

Since the electrode connection is in front of the rollers, it not only helps to shield the rollers from the heat of the arc, but the electrical potential is greater at the electrode connection than at the rollers.

Because the connection at 13 is made with the separable member 49, the latter in the event of corrosion caused by the current can be readily replaced.

As the shield 56 is in front of the electrode connection 62, it insulates the latter from the heat of the are, so as to help keep the contact resistance at a minimum. Any heat caused by such resistance will not materially affect the shield, as the latter consists of refractory, and is well adapted to withstand the intense radiation from the carbon arc. The rollers are all exposed to radiate heat transmitted thereto.

The shield 56 cannot melt or fuse, so as to tend to close the hole 59, and thus interference with the movement of the carbon stick is avoided. The shield has low heat conductivity and therefore acts as an insulation member. If the shield becomes broken, it may be readily replaced.

Moreover, the shield may constitute a heat radiator to efficiently dissipate the heat away from the feeder head.

The feeding means or rollers, and the shield and electrode connection are all in close or direct proximity to each other, or in substantial contact or engagement with each other, to afford a compact unit which permits the rollers to lie as far forward as possible, so that only a very small piece of the carbon stick is wasted according to the objects of the invention hereinbefore set forth.

It will be seen that the maximum wear on the bearings for the roller shafts occurs in proximity to the rollers, at the upright flange of the angle member 49. Hence when the bearings are worn, it is sufiicient merely to replace the angle member 49, instead of fitting new bearing parts. Moreover, bearings for shafts 23, 21 are spaced away from the electrode connection, with the rollers 30, 3| intervening.

By this invention, therefore, the primary purpose of saving carbon is accomplished by a simple device having various additional features 01 advantage.

It will be appreciated that various changes and modifications may be made in the device as shown in the drawing, and that the same is submitted merely in an illustrative and not in a limiting sense, the scope of the invention being defined in the following claims.

We claim:

1. A rotary carbon electrode feeding head including a plurality of angularly spaced rollers disposed along a transverse to the horizontal axis of said head for feeding and rotating the carbon electrode therebetween, a relatively stationary ring shaped carbon contact for movably receiving the carbon electrode, and a refractory shield having an opening for passage of a carbon electrode therethrough, said shield and said contact being of relatively minimum thickness and yet providing adequate heat shielding and transmission of current, respectively, said contact being intermediate of said shield and said rollers, the latter and the shield and contact lying in parallel planes in close proximity to each other, a support having a drive for the rollers, a bracket removably mounted on the support, shafts for the rollers, and bearing means for the shafts carried by the support, including bearings mounted on the bracket and removable as a unit therewith, whereby a carbon electrode can be fed and burned down to leave a stump of minimum length.

2. A rotary carbon electrode feeding head, including a support, a relatively thin refractory shield means having a central passage, an arm removably connected to said support, means removably interconnecting the shield means and the arm in a U shaped formation with the shield means mounted on the arm, a relatively thin electrical ring contact means and a roller feeding means between said shield means and the arm and in alinement with said passage, said roller feeding means being mounted on said arm, with said contact means between the shield means and the roller feeding means, and the diflerent means disposed in relatively close proximity to each other.

CHARLES A. FUCHS. FRANK SPALOSS.

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