FI68544B - SAETT ATT REPARERA ELLER AOTERSTAELLA SLITNA ELLER SKADADE DRIVAXLAR SAERSKILT PROPELLERAXLAR - Google Patents

Description

RSCiTl rRl M ,, ANNOUNCEMENT s nc λ λ • 5§Ri Β <11) utläggningsskrift 6 8544 • JSS (45) (51) Kv.lk. «/ Lnt.CI.4 Β 23 Ρ 6/00 FINLAND —FINLAND ( 21> Patent application - Patentansökning 760353 (22) Application date - Ansöknlngsdag 12.02.76 (23) Starting date - Giltighetsdag 12.02.76 (41) Has become public - Blivlt offentlig 14.08.76

National Board of Patents and Registration / 44) Date of sight and hearing | - 28.06.85

Patent and registration authorities of the United Kingdom of Great Britain and Northern Ireland (32) (33) (31) Privilege requested - Begird priorltet 13-02.75 Iso-Br i Tann ia-Storbr itann ien (GB) 6163/75 (71) ( 72) Donald Kenneth Healey, 31 Harbor View Road, Poole, Dorset,

Iso-Br i Tann ia-Storbr i Tann ien (GB) (7 * 0 Berggren Oy Ab (5 * 0 Way to repair or replace worn or damaged drive shafts, especially propeller shafts - Sätt att reparera eller äterställa slitna ellad skadade drivaxlar, särskilt propelleraxlar

The present invention is directed to a method of repairing or rebuilding damaged drive shafts, especially propeller shafts, by electrically welding a helical welding wire to the shaft and machining it to provide a finished surface.

It is previously known to repair worn drive shaft areas by a metal spray method or flame coating, but such repairs involve certain disadvantages. A particular disadvantage is that the coating metal does not adhere properly to the shaft and can thus become detached during use. In addition to this, the injected metal is porous in nature, which under sea conditions results in the intrusion of brine causing early detachment and damage to the bearings. Electrolytic effects or simply poor adhesion of the sprayed layer also lead to damage. It has also been proposed to weld the wires to the length of the damaged area of the shaft. However, this method is not only time consuming and difficult to apply to automated processes, but also results in a significant change in the bending shape of the shaft, which can only be partially corrected by placing successive wires on opposite sides of the shaft cross section, greatly complicating the method.

It is an object of the present invention to provide a method which avoids the above-mentioned damage and which can be applied to the repair of shafts of all sizes. In addition, it is intended to provide a method which can be easily applied to the repair of a wide variety of worn or corroded areas.

To achieve this, the invention is characterized in that the shaft is rotated and the welding wire is passed through an inert gas shielded gun located immediately adjacent to the shaft and moved synchronously with the rotation of the shaft in its longitudinal direction, the current being selected so that the contact zone between the shaft and wire heats up to the welding temperature and the fusible material is welded to the turns adjacent to the welding wire as well as to the shaft.

Thus, a method is achieved in which a continuous weld made of a metal identical to or compatible with the shaft is fixed around the worn or damaged area of the shaft by rotation and the continuously fed wire turns are simultaneously welded to the shaft as a layer of compatible welding metal using a noble gas or other fused

The voltage and current used in this connection guarantee a correct and even penetration suitable for the shaft and the welding material in question. In most cases, the welding is self-normalizing, and if the welding process is performed to a suitable end point that allows heat conduction, then the risk of surface damage is low.

The process according to the invention has proved to be less time-consuming than previously known processes and poses a lower risk of deformation on the shaft or of the composition of the parent metal li 3 68544 in the deeper layers.

The invention will now be described in more detail in the form of examples and with reference to the accompanying drawing, which shows an apparatus for carrying out the method according to the invention by means of a conventional lathe.

As shown in the figure, the shaft 1 to be repaired is mounted on the support bearings 3 and b for rotation via the machine rotating plate 5. The lathe carriage 5 supports an arc welding device 6 provided with a shielding gas supply and a wire 7. The height of the welding device can be changed. The carriage 5 also supports the cutting tool and the bracket 9.

The following examples, together with the table, show the various parameters for the numerous combinations and shaft and wire dimensions.

The examples use Norman Butter and Company Limited's marks NBC 350 or NBC 500 for currents of 350 A and 500 A, respectively, as the welding device, the parameter "wire feed speed" being read from the meter of said device. All examples had. polarity positive for welding electrode and negative for workpiece. Other sizes with different diameters can be calculated on the basis of the presented data to achieve satisfactory results. The wire brush is used for welding:. On the opposite side of the stool in the workpiece to remove any splashes that can cause porous spots, especially when attaching successive layers. The constant voltage is kept the same in all cases.

In the preferred example of repairing a marine drive shaft, worn or damaged areas are chemically or mechanically cleaned, straightened as needed, and then the metal wire is fed to the rotating shaft and heat is applied locally to the wire-shaft joint to connect the two, said _____-IL. --- il 68544 as the process continues under lateral displacement along the damaged area until the helical layers of the formed metal coating cover this area to a depth sufficient to allow subsequent machining to its original cross-sectional dimension, or to a greater or lesser extent.

The attached wire is preferably the same or similar metal alloy as the shaft, although very different metals may be used, depending on their ability to form a connection with the shaft. The goat is wound on the shaft by twisting it and feeding the welding wire with a gas- or fusible-protected welding gun, which is placed close to the shaft and moved longitudinally as the wrapping continues. In this way, a homogeneous association of the metal with the metal of the original shaft is achieved along the damaged area, and subsequent machining allows the surface to be corrected to its original condition and thickness or to be increased in diameter.

The method is particularly suitable for use with metal coating of worn bearing areas or corroded areas on a shaft.

Shaft rotation speed, wire diameter, wire type, operating speed, current, shielding gas or gas mixture or molten material, gas flow, electrode lateral speed, wire feed speed, live workpiece conditions, induction, electrode polarity and workpiece weather, workpiece polarity the welding method used. The rotational speed of the workpiece, its configuration and the size and composition of the wire, its feed rate and the associated arc voltage and current, including the shielding gas or molten material mixture, depend on each combination of workpiece, wire and material composition and are different from each other.

These interrelationships are complex and require experiments to be performed to achieve optimal results. The parameters for special applications are given in connection with you as an example.

5,68544

The invention can also be applied to the repair of bearing or aluminum bronze or alloy bearing bushes in marine propeller shafts. In the past, even after a slight wear, such shafts have been machined away and a new jog has been made to fit and shrink the shaft, after which the shaft has been finished by machining and straightened.

When using the method of the invention in propeller shafts or other marine component parts exposed to brine, a chemical desalination process is used as part of the preliminary cleaning procedure.

In practice, repairs to worn shafts or similar parts are performed by rotating a shaft in a lathe or similar machine that is capable of rotating at a precisely controlled speed. The speed can be as low as 0.2 rpm and is determined by the shaft diameter and the degree of metal coating. Furthermore, the speed of the transverse feed for the welding head in the region of the axis to be repaired varies and is closely monitored in relation to the rotational speed by means of a speed-independent motor, which in turn is monitored by a variable potentiometer.

Existing machines can be easily modified to carry out the method according to the invention, in which case special attention must be paid to the sliding surfaces of the machine to protect them from hit splashes and to the way of supplying power to the shaft. Due to the high DC currents used, the supply through the machine bearings is usually unsuitable for use, as the high current and the subsequent generation of sparks damage the bearing surfaces of the machine and lead to changes in the welding current.

This problem is overcome by equipping the machine with a brush member in contact with the spindle shaft of the machine or a contact sleeve thereon, or the brush member can also be connected to the workpiece by means of a belt connection to close the circuit.

6 6 85 4 4

As an example, a fifty millimeter diameter stainless steel shaft was rotated at four rpm, and a 0.8 mm stainless steel wire was connected to the shaft and fed through a low voltage argon gas shielded arc. The shaft area was then turned and ground to its final dimensions. This type of work can be performed on the basis of predetermined data, whereby heat conduction can be minimized and all detrimental effects can be reduced in the parent metal or associated welding.

Conventional repair methods using metal spraying cannot be used due to the porosity of the repair, which allows brine to penetrate through and the subsequent detachment of the metal layers. This is avoided by the method according to the invention.

Marine propeller shafts use a chemical desalination process as a preliminary step.

68544 7

Example Shaft Wire Welding machine 1 Stainless steel EN18C Aluminum bronze NBC350 BS2901 part 3 2 Aluminum bronze DGS8452 "NBC500 3 Aluminum bronze" "4 Monel K500 Monel 60 NBC350 5" "" "NBC500 6 Stainless steel EN18C Stainless steel 29 / 9R NBC350 BSC350 EN58J Inconel 625 NBC500

g Tl TT M 11 TT TT

9 Bearing bronze BS1400 Phosnic NBC350 (Ni 1.38: Mn 0.22:

Si 0.46: P 0.021:

Sn 5,22: Residual part Cu) 10 Bearing bronze BS1400 Phosnic NBC500 1969 11 Bearing bronze, British Phosnic N "Age Adm.Spec. DGS203 or LG4 12 Cast steel EN3C PZ.6000 BS2901 NBC350 part 1, AI 6 13 Cast steel EN3B" "14 Cast steel EN3C "NBC500 15 EN5K C: 0.25 * 0.35 PZ.6000 C: 0.25-0.3"

Si: 0.0 5_0.35 Si: 0.3 ~ 0.5

Mn: 0.6-1.0 Mn: 1.3-1.6 S: 0.0 5 P: 0.05 S: 0.04 P: 0.04 16 Cast steel EN3L PZ.6000 BS.2901 "part 1 AI 6 t »tr ir n 18 EN5K PZ.6000" 68544 8

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SETTING UP A SPECIFIC DEVICE

EXAMPLE # -

Coarse Force- Fine Inductance- Voltage scaleVoltage monitoring 1 D Low 4 100 2 B Low 5 100 3 D Low 2 100 4 D Low A 100 5 C Low 4-6 100 6 D Low A 100 7 D Low 5-6 6, 5 8 D Low 3-5 70 9 D Low 4-5 0 10 D Low 5 0 11 A High 3 0 12 D Low 4 100 13 D Low 4 100 14 C Low 5-6 6.5 15 D Low 3 70 16 D Low 3 70 17 D Low 3 70 18 A High 1 70

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