US2446278A - Arc lamp or the like - Google Patents

Description

Aug. 3, 1948. c. G. H. HALLETT ARC LAMPS OR THE LIKE Filed Oct. 28, 1947 Patented Aug. 3, 1948 ARC LAMP OR THE LIKE Charles Gordon Heys Hallett, London, England, assignor to Morgan Crucible Company Limited, London, England, a company of Great Britain Application October 28, 1947, Serial No. 782,595 In Great Britain March 29, 1947 11 Claims. 1

This invention relates to improvements in the contacts which carry the current into the electrodes in arc lamps, electric welding machines and the like.

It provides an improvement in or development of the invention contained in our co-pending application, Patent No. 2,442,409, filed June 3, 1946 for Improvements in and relating to are lamps or the like according to which the contact blocks each comprise a series of wedge elements, one behind the other, coacting with a corresponding series of sloping surfaces formed in the electrode holder so that a thrust parallel to the electrode, i. e. a longitudinal thrust, causes the contact block to bear with pressure upon the electrode holder and upon the electrode. More particularly the wedge elements of the contact block substantially produce a helical formation matching a helical thread in the electrode holder. With this latter arrangement there is a, tendency in cases where the electrode is fed with a rotary movement, for the contact block assembly to become unscrewed, and the object of the present invention is to counteract such tendency.

The present invention accordingly provides a device in the nose-piece of the electrode holder whereby the contact blocks are prevented from rotation with the electrode and which ensures that, although the contact blocks are prevented from such movement, they will be free to move, under spring pressure or other yielding longitudinal thrust, sufficiently to produce the required wedge action.

The invention is illustrated in the accompanying drawings in which Fig. l is a part sectional elevation of a nose-piece of an electrode holder, Fig. 2 is a section on the line 22. Fig. 1 and Figs. 3 and 4 are sectional elevations of modified forms of apparatus.

Referring to the drawings the nose-piece indicated generally at I of the electrode holder 2 is provided with an opening at the front 3 for the insertion of the contact blocks 4 which are adapted to be screwed home by means of a suitable tool, and within the electrode holder is rotatably accommodated a member 5 adapted to interlock with the contact blocks 4 so as to be rotated there with during the last part of the screwing operation, the said member 5 being provided with one or more longitudinal slots 5 for receiving a looking pin or detent I which can be brought into and out of operation at will.

The rear ends of the contact blocks 4 are formed with a series of dogs 8 which engage, when the contact blocks have been screwed some distance (Cl. l76119) into the electrode holder 2, with a corresponding series of dogs 9 on the interlocking member '5 so as to produce a-dog-clutch. The dogs 8,9 are so shaped as to permit free movement of the contact blocks 4 in a radial direction. The interlocking member 5 conveniently takes the form of a sleeve annularly disposed around the electrode it, which sleeve is formed internally, e. grwitha flange II, so as to provide a seating for a .com-. pression spring I2 transmitting longitudinalthrust to the contact blocks 4.

The locking pin I is preferably housed within a centrally bored bush I3 which is screwed into, the side wall I4 of the electrode holder 2, have ing a cylindrical recess I5 in its inner end to ace commodate a small compression spring I6 mounte ed under a collar I1 on the pin I so as normally to urge the pin into a retracted position. The outer end of the pin I carries a knob I8 easily ac-v cessible to the operator of the arc lamp and adapted when depressed to. be locked in that position, for example by means of a bayonet fastening I9.

In operation the contact blocks 4 are screwed into the electrode holder 2 by means of a suitable tool until the dogs 8 located on their rear. ends engage the corresponding dogs 9 locatedon the end of the sleeve 5. Thereupon the sleeve 5 rotates with the contact blocks 4, the locking pin i being in the retracted position, and is forced back with the contact blocks 4 against the action of the compression spring I2 whose end is housed in the sleeve. When the contact blocks 4 have been screwed fully home or substantially so, a longitudinal slot 6 in the sleeve 5 being in register beneath the retracted locking pin I, the pin is depressed into the slot 6 by its external knob I8 and the latter is turned so as to lock the pin. The sleeve 5 and the associated contact blocks 4 are then looked against rotation.

In the modification shown in Fig. 3 the locking pin I is engaged at its outer end by a leaf spring at mounted on the outside of the electrode holder 2, one end of the spring being anchored to the holder at 2| and the other terminating in an out wardly curved portion 22 which serves as a finger grip. By grasping the finger grip 22, the spring 20 may be lifted to retract the locking pin I and disengage it from the sleeve 5. When the spring 29 is released the locking pin I will be depressed.

In a further modification shown in Fig. 4 the locking pin I is formed with a collar 23 engaged on its underside by a trip lever 24 actuated by a pivoted saddle 25 so that when the latter is depressed the locking pin I will be retracted against the action of a spring 26.

What I claim is:

1. The combination of an electrode, an electrode holder, and a plurality of complementary contact blocks surrounding the electrode and interposed between the electrode and the electrode holder, each contact block having a series of surfaces sloping towards the electrode which in the assembly of contact blocks produce a helical formation and the electrode holder having a helical thread matching said helical formation, and means for locking the contact blocks against rotation in the electrode holder.

2. The combination as claimed in claim 1 wherein the locking means includes a member rotatably accommodated within the electrode holder, said member being adapted to interlock with the contact blocks so as to be rotated therewith during the last part of the screwing operation when the contact blocks are screwed home, and means operable to lock said member against rotation.

3. The combination as claimed in claim 1 wherein the locking means includes a member rotatably accommodated within the electrode holder, dogs formed on said member adapted to interlock with the contact blocks so that said member is rotated therewith during the last part of the screwing operation when the contact blocks are screwed'home, and means operable to lock said member against rotation.

4. The combination as claimed in claim 1 including a locking member in the form of a sleeve annularly disposed around the electrode, a compression spring for transmitting longitudinal thrustupon the contact blocks, said sleeve being formed internally with a flange so as to provide a seating for said compression spring and being formed with at least one longitudinal slot, and a locking device engageable with said slot.

5. The combination as claimed in claim 1 including a locking member formed with at least one longitudinal slot, a locking pin, engageable with said slot, a centrally bored bush screwed with the electrode holder and accommodating said pin, and a compression spring mounted in said bush to urge the pin out of engagement with said slot.

6. The combination as claimed in claim 1 including a locking member formed with at least one longitudinal slot, a locking pin engageable with said slot, a centrally bored bush screwed into the electrode hold-er and accommodating said pin, a compression spring mounted in said bush to urge the pin out of engagement with said slot, and a projection carried by the pin for engagement with a recess formed in the bush to lock the pin in engagement with said slot.

7. The combination as claimed in claim 1 including a locking member formed with at least one longitudinal slot, a locking pin engageable with said slot, a leaf spring mounted on the outside of the electrode holder and bearing on said pin, one end of said spring being anchored to the holder and the other terminating in a curved portion serving as a, finger grip.

8. The combination as claimed in claim 1 including a, locking member formed with at least one longitudinal slot, a locking pin engageable with said slot, a collar formed on said pin, a trip lever engaging the underside of said collar, and a pivoted saddle which when depressed actuates the trip lever to withdraw the pin from engagement with said slot.

9. The combination of an electrode, an electrode holder, and a plurality of complementary contact blocks surrounding the electrode and interposed between the electrode and the electrode holder, each contact block having a series of surfaces sloping towards the electrode which in the assembly of contact blocks produce a helical formation and the electrode holder having a helical thread matching said helical formation, and means for locking the contact blocks against rotation in the electrode holder, said electrode holder comprising a nose piece provided with an opening for the insertion and screwing home of the contact blocks.

10. The combination as claimed in claim 9 wherein the locking means includes a member rotatably accommodated within the nose piece of the electrode holder, dogs formed on said member, correspondingly formed dogs on the contact blocks adapted to interlock with the dogs formed on said member, so that said member is rotated therewith during the last part of the screwing operation when the contact blocks are screwed home, and means operable to lock said member against rotation.

11. The combination as claimed in claim 9 wherein the locking means includes =a, member rotatably accommodated within the nose-piece of the electrode holder, dogs formed on said member,

correspondingly formed dogs on the contact blocks adapted to interlock with the dogs formed on said member, the correspondingly formed dogs being so shaped as to permit relative movement of the contact blocks in a radial direction, and means operable at will to lock said member against rotation.

CHARLES GORDON HEYS HALLETT.

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