CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage of International Application No. PCT/EP2019/071560 filed 12 Aug. 2019, and claims the benefit thereof. The International Application claims the benefit of European Application No. EP18203327 filed 30 Oct. 2018. All of the applications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The present disclosure relates to a safety apparatus for containing loads applied to shaft arrangements particularly, but not exclusively for turbo engines and turbo-machines having a compressor, a turbine or a power turbine mounted to an axial shaft.

BACKGROUND

In gas turbine engines, compressors and turbines typically have axially arranged sets of rotors, each comprising an array of blades mounted to rotor discs. The respective sets of rotors are located between end shafts on a tension stud that extends through all or part of the set of rotors. In operation, the rotation of the rotors causes high separation forces to develop in the rotors. To counter these separation loads, a compression load is applied to the shaft and the rotors prior to use to offset the separation loads that develop in operation. To develop the compression load in the shaft and rotors, the tension stud is stretched during assembly to develop a tension within the tension stud. The tension stud is then held in its stretched form by a load retainer that engages with the shaft. The tension stud will react against the shaft via the load retainer to apply the compression load to the shaft.

Due to the high loads required to counter the separation loads encountered in operation, the risk of injury to assembly fitters as a result of failure of one or more components of the rotor assembly is high.

To overcome this problem, each component of the tooling assemblies is designed with a high factor of safety, which leads to increased size and weight of each component as well as increased expense. Further, each component is subject to regular non-destructive testing, which is time-consuming.

An alternative solution to overcome this problem is to utilise a robotic assembly to avoid interaction of an operator with the tool assembly during loading of the tension stud. However, this leads to significant expense.

Hence a need for improved safety when applying loads to a tension stud is highly desirable.

SUMMARY

According to the present disclosure there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

According to a first aspect of the invention, there is provided a safety apparatus for containing a release of energy from a tension stud of a rotor assembly. The safety apparatus including a containment member configured to pivot about a pivot location. The containment member including a tail located on a first side of the pivot location, an elongate region on a second side of the pivot location, the elongate region defining a longitudinal axis and an arm located towards a distal end of the elongate region and projecting away from the longitudinal axis of the elongate region. The containment member is configured to be connected to a tool apparatus for applying a load energy to the tension stud. In use, the containment member is configured to pivot between an open position and a containment position in which the arm overlaps with at least part of the tool apparatus in the direction of the longitudinal axis of the elongate region to contain the load energy within the safety apparatus. Hence there is provided a safety apparatus suitable for containing a load applied to a tension stud of a rotor assembly in the event of a failure of one or more components and/or connections of the rotor assembly. The provision of the safety apparatus significantly reduces the risk to nearby workers and equipment as any energy released by a failure of one or more components will be restrained by the safety apparatus. Further, the provision of safety apparatus as part of the tool assembly avoids the necessity to redesign current components, which are already in operation.

The tail may be enlarged towards a proximal end and may be configured to engage with a lip of a shaft of a rotor assembly. Providing an enlarged region of the tail enables the safety apparatus to work with the existing geometry of the rotor assembly, i.e. no changes are required to the geometry of the rotor assembly.

In one example, the arm defines a second axis, wherein the longitudinal axis and the second axis are substantially perpendicular.

In one example, there is provided a tool assembly for applying a load to a tension stud of a rotor assembly. The tool assembly may include at least one safety apparatus and a tool apparatus. The tool apparatus may include a tool head for connecting to the tension stud, a compression body for engaging with a shaft of the rotor assembly and an actuator located between the tool head and compression body for applying a load to the tool head and the compression body. In this example, the at least one safety apparatus is connected to the tool apparatus and in the containment position at least part of the arm overlaps with at least part of the tool head in the direction of the longitudinal axis of the elongate region. The provision of the tool assembly including the safety apparatus enables the load to be applied to the tension stud and shaft of a rotor assembly in a safe manner.

The tool assembly may include two diametrically opposed safety apparatus connected to the tool apparatus. The provision of two diametrically opposed safety apparatus means that the energy released as a result of a failure will be shared between the two safety apparatus.

The tool assembly may include a biasing member configured to bias the containment member in the open position.

The tool head may include a removable insert and the removable insert may include a male thread for engaging with a co-operative female thread of the tool head and a female thread for engaging with a co-operative male thread of the tension stud. The removable insert may be made of a higher grade material compared with the rest of the tool head and so prolong the usable lifetime of the tool head.

In one example, the compression body includes a substantially cylindrical sidewall comprising an aperture. The provision of a substantially cylindrical sidewall comprising an aperture enables an operator to access the inside of the compression body. In one example, the operator is able to access a connector connected to a load retainer within the compression body.

The tool assembly may include a rotatable sleeve including a cam shaped outer profile. The tail of the containment member may be configured to engage with the outer profile of the rotatable sleeve such that rotation of the rotatable sleeve causes the containment member to move between the open position and the containment position. The sleeve with the cam shaped outer profile enables the containment member to be moved between the containment and open positions.

The rotatable sleeve may include at least one handle to enable the sleeve to be rotated.

In one example, the tool apparatus includes a location member and the sleeve comprises a slotted aperture configured to receive the location member, wherein the slotted aperture and location member are sized to restrict rotation of the sleeve through a pre-determined angle.

The tool assembly may include a measurement apparatus configured to measure the elongation of the tension stud. The measurement apparatus may be used to determine that the tension stud has extended by a pre-determined amount, equivalent to a pre-determined tension load being developed in the tension stud and hence, a pre-determined compression load being applied to the shaft.

According to another aspect of the invention, there is provided a method of applying a load to a tension stud of a rotor assembly, the method including connecting the tool head of the tool assembly to a tension stud, engaging the compression body of the tool assembly with a shaft of the rotor assembly, engaging the tail of the containment member with the shaft of the rotor assembly, moving the containment member of the safety apparatus to the containment position and actuating the actuator of the tool assembly to apply a compressive force to the tool head and the compression body to cause a tension load in the tension stud. This method enables a load to be safely applied to the tension stud.

The step of moving the containment member may include the step of rotating the sleeve.

The method may also include the steps of determining that the tension stud has elongated by a predetermined amount; and rotating a connector connected to a load retainer which is co-operatively threaded to the tension stud, wherein the load retainer is moved so that it engages with the shaft of the rotor assembly.

