Method and apparatus for improved cutting life of a plasma arc torch
AssigneeHypertherm, Inc.
InventorsJonathan P. Mather, Peter J. Twarog
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Abstract
An improved electrode for use in a plasma arc torch. The electrode includes an electrode body, a cavity in a front face at a first end of the electrode body, and an insert disposed in the cavity. The first end of the electrode body is formed of high purity copper containing at least 99.81% copper. The insert has a first end and a second end and is formed of a high emissivity material. A diameter of the first end of the insert is less than a diameter of a second end of the insert. An electrode is compressed to retain the insert using radial compression. The invention also includes a method for forming the electrode, and a method of operation of an electrode in a plasma torch.
Claims20
An electrode for a plasma arc torch having a prolonged service life, the plasma arc torch including a plasma chamber defined by the electrode and a nozzle, the electrode comprising:
- an electrode body having a front face at a first end of the electrode body;
- an orifice in the front face of the electrode body;
- and
- an elongated emissive insert made of a high thermionic emissivity material and located within the orifice, the insert having a forward end and a rearward end, wherein the forward end of the insert is oriented toward the front face of the electrode body,
- wherein the insert has an initial configuration and an operational configuration, the operational configuration being formed after a plurality of operations of the torch,
- the initial configuration of the insert having the rearward end of the insert located at a first distance (D1) from the front face, and the operational configuration of the insert having the rearward end located at a second distance (D2), wherein D1 is at least 0.6 mm greater than D2 based upon at least two of the following:
- (i) the electrode is formed of a high purity copper containing at least 99.81% copper;
- (ii) radial compression is applied at the first end of the electrode body to retain the insert;
- or
- (iii) the insert is tapered, such that a diameter of the forward end of the insert is less than a diameter of the rearward end of the insert.
A method for extending service life of an electrode for a plasma arc torch, the method comprising:
- forming a pit in a first end of an insert, the insert formed of a high thermionic emissivity material having the first end and a second end and disposed within a cavity in a front face at a first end of the electrode, the insert having an initial configuration and an operational configuration, the operational configuration being formed after a plurality of operations of the plasma arc torch;
- cycling the electrode thermally, thereby causing melting of a portion of the insert based upon emission of a plasma arc from the insert during each operation of the torch, the insert advancing toward the front face of the electrode in connection with the thermal cycling;
- and
- preventing a premature failure of the electrode due to the advancement of the second end of the insert toward the front face of the electrode by a distance of at least 0.6 mm during the thermal cycling of the torch, such that in the initial configuration the rearward end of the insert is located at a first distance (D1) from the front face and wherein in the operational configuration the rearward end is located at a second distance (D2), wherein D1 is at least 0.6 mm greater than D2,
- wherein the preventing of the premature failure includes using at least two of the following:
- (i) the electrode is formed of high purity copper comprising at least 99.81% copper;
- (ii) radial compression is applied at the first end of the electrode body to retain the insert;
- or
- (iii) the insert is tapered, such that a diameter of the first end of the insert is less than a diameter of the second end of the insert.
Dependencies are inferred from the claim text.