FIELD OF INVENTION

The present invention relates to the field of civil and mechanical engineering more particularly a hinge/pivot/gimbal to either structural systems e.g. columns, guyed mast, beam ends, trusses, etc. or mechanical systems e.g. rotary shafts/components, crane boom ends, etc. It helps in eliminating the torsional forces on the guyed mast or temporary support structural system under unbalanced lateral loads generated during the erection and service life, facilitates the horizontal assembly of guyed structural mast and then allows lifting of assembled mast for erection purpose by pulling the structure using wire rope through Y-frame, provides pivot to the rotary mechanisms, etc.

BACKGROUND AND PRIOR ART OF THE INVENTION:

Structural hinges are analogue parts of the structural systems to transfer forces efficiently and economically from columns or latticed masts or truss ends or beam/girder ends to the foundations/bases. Other forms of hinges in mechanical systems are also the essential components to form mechanisms or to support rotary shafts pivot ends or to support equipment bases or crane booms, etc.

Based on the literature review, it is found that the research towards the development of two pin gimbal joint is the state-of-the-art. To this, there are different solutions available in market but either their concept, design and construction/fabrication is quite different or cumbersome or handling is difficult. Most of the literature is pertaining to the mechanical hinges, reference may be made to Hopkins (1915) and Preston (1966), wherein the universal joints were developed with a coupling fork and used as pivot to a rotary shaft or the high angular torque is transmitted between the shafts using a bevel gear system or reference may be made to Wood and krch (1993), wherein a quick acting gimbal joint was developed as an improved linkage assembly for locking the pivotable position of one member relative to another member by using combination of apertures and splines. All the above hinges reviewed are mechanical systems and many more such systems are invented over the period of time but the present invention is focused for its primary use to support heavy structural systems and it also can be used for mechanical systems. Hence, literature related to mechanical hinges is reviewed for limited systems. Very few systems related to structural hinges are available in market, reference may be made to Lindsey (1988) and Zhao (2009) wherein structural hinge used for guyed masts of temporary support structures to power lines is developed using a specially manufactured gimbal shafts or reference may be made to Zhu (2008) wherein a steel structure gimbal is invented, which relates to a steel structure universal supporting seat formed by movable connection of a bottom board and a gusset plate. The drawbacks of these systems that either they are made with spherical components or special gimbal shafts thus requiring precision machining or complicated forging of components. Moreover, whole assembly of the gimbal joint needs to be handled at site which is bulky and heavy.

In addition, the available systems design and construction/fabrication is cumbersome, handling is difficult at site and their cost is very high. In view of the above, a cost effective two pin gimbal joint with improved, safe and stable lightweight design, easy to fabricate, assemble, dismantle and install at site is the need of the hour.

Patent citation:

1. US1153789, 14/09/1915, H.F. Hopkins and C. Hopkins - Universal joint

2. US3260070, 12/07/1966, M. Preston - Universal joint

3. US5197817, 30/03/1993, W.B. Wood and G.D. Krch - Quick acting gimbal joint

4. US4769959A, 13/09/1988, K.E. Lindsey - Temporary power line tower assembly and method of installing same

5. CN100363566C, 23/01/2008, Zhu Xinggang - Steel structure gimbal

6. CN201372599Y, 30/12/2009, Zhao Mingxing and Wei Haiou - Fast first-aid repair system for transmission line

OBJECTS OF THE INVENTION

1. The main object of the present invention is to provide a two pin gimbal joint which obviates the drawbacks of the hitherto known prior art as detailed above.

2. Another object of the present invention is to design and fabricate lightweight two pin gimbal joint with plate elements made of structural grade aluminum alloy which will confirms the qualification criteria as per IEEE 1070 standard for its use as structural hinge of guyed mast of temporary support structural systems for power lines

3. Still another object of the present invention is to design and fabricate the two pin gimbal joint made of steel which will be of higher capacity to support heavy structural systems or mechanical systems. 4. Yet another object of the present invention is to design the structural hinge to facilitate horizontal assembly of bottom conical panel and first panel of a guyed mast of temporary support structural system for power lines and then allow lifting of assembled mast for erection purpose by pulling the structure using wire rope through Y-frame.

SUMMARY OF THE INVENTION

An easy to fabricate and use, two pin gimbal joint has been developed to support the guyed mast of temporary support structural system or other guyed mast, truss ends, beam/girder ends or rotary shafts or crane boom ends, etc. While developing the present system, number of inventive features has been added which makes the system more efficient, cost effective and novel compared to other solutions available in market. In this system the top and bottom plate assemblies are designed with plates made of structural grade aluminum alloy which makes it lightweight. Experimental investigations were carried out as per IEEE 1070-2006(R2012) standard on its assemblies at sub-structure level as a component of temporary support structural system and a prototype of a temporary support structural system equivalent to 220 kV single circuit transmission line tower using present inventions as structural hinge is also tested as per IS: 802 (Part III) - 1978 (Reaffirmed 2003) and IEC 60652: 2006 standard for the design loads calculated as per IS 802 (Part 1/Sec 1): 2015. This is to ascertain the structural responses for their comparison with the design standards values. The design, development and experimental works has been completed.

Performance evaluation of two pin gimbal joint used in demo temporary support structural system for power line for a typical configuration (double circuit) with a typical voltage class (400 kV) suspension type tower confirming to IS 802 (Part 1/Sec 1): 2015 and CBIP Manual on Transmission Lines Publication No. 323, July 2014 has been observed over three years’ period under practical conditions.

BRIEF DESCRIPTION OF THE FIGURES

The present invention is illustrated in figure 1 to 8 of the drawings accompanying this specification. In the drawings like reference numbers/letters indicate corresponding parts in the various figures.

Figure 1 (a to c) represents the perspective view (a), elevation (b) and side view (c) of the two pin gimbal joint indicating all the main components/parts of the joint. Figure 2 represents the plan (a), elevation (b) and side view (c) of the top plate assembly of the two pin gimbal joint.

Figure 3 represents the plan (a), elevation (b) and side view (c) of the bottom plate assembly of the two pin gimbal joint.

Figure 4 represents the test setup for the compression test on prototype two pin gimbal joint.

Figures 5 represents the schematic of gimbal articulation test a qualification criterion for gimbal joint as per IEEE 1070 standard.

Figures 6 represents the schematic (a) and test setup (b) of gimbal compression test along with bottom conical panel of temporary support structural system a qualification criterion for gimbal joint as per IEEE 1070 standard.

Figures 7 represents the schematic (a) and test setup (b) of gimbal transverse test along with bottom conical panel of temporary support structural system a qualification criterion for gimbal joint as per IEEE 1070 standard.

Figure 8 represents the view of horizontal assembly of bottom conical panel and first panel of a temporary support structural system for power lines during its erection.

STATEMENT OF THE INVENTION

1. Accordingly, the present invention provides two pin gimbal joint (1) which comprises a. top plate assembly (2) directly connected with the bottom part of supported guyed mast or structure or other structural/mechanical systems using high strength steel fasteners; b. the top plate assembly (2) and bottom plate assembly (3) are connected with a horizontal pin (4) made of high strength steel fastener, thus it allows rotation of top plate assembly (2) with supported structure at 180° in vertical plane. c. the bottom plate assembly (3) is connected to the supporting structure/base/box of foundation plate used in temporary support structure with a vertical pin (5) which allows rotation of the gimbal joint assembly along-with supported structure at 360° in horizontal plane. d. the whole assembly of joint (1) allows movement of supported structure virtually to any point on top half surface of sphere. e. In an embodiment of the present invention, a two pin gimbal joint is developed which obviates the drawbacks of the hitherto known prior art. f. In another embodiment of the present invention, the design is carried out for the fabrication of lightweight two pin gimbal joint with plate elements made of structural grade aluminum alloy which will confirm the qualification criteria as per IEEE 1070 standard for the use as structural hinge of guyed mast of temporary support structural systems for power lines and also tested for evaluating its compression load carrying capacity.

In yet another embodiment of the present invention, the design is carried out for the fabrication with plate elements made of steel which is tested for evaluating its compression load carrying capacity for the use in other systems viz. as structural hinge in columns, trusses ends, beam/girder ends, etc. and as mechanical hinges to support rotary shafts, crane booms, etc.

In still another embodiment of the present invention, the two pin gimbal joint is designed to facilitate horizontal assembly of bottom conical panel and first panel of a guyed mast of temporary support structural system for power lines and then it allows lifting of assembled mast for erection purpose by pulling the structure using wire rope through Y-frame.

DETAILED DESCRIPTION OF THE INVENTION

Details of the present inventions are shown in Figures 1 to 3. The proposed two pin gimbal joint (1) is used to support the guyed mast of structural systems or temporary support structural system or the structural columns or beam ends or truss ends or the rotary shafts of mechanical systems or crane boom ends, etc. The top plate assembly (2) of the present invention is directly connected with the bottom part of supported stricter or other systems using high strength steel fasteners. The top plate assembly (2) and Bottom plate assembly (3) of the two pin gimbal joint (1) are connected with a horizontal pin (4) made of high strength steel fastener, thus it allows rotation of top plate assembly (2) with supported structure at 180° in vertical plane. Further, the bottom plate assembly (3) of two pin gimbal joint (1) is connected to supporting structure/base/box of foundation plate used in temporary support structure with a vertical pin (5) which allows rotation of the gimbal joint assembly with supported structure at 360° in horizontal plane. Thus, by using present invention i.e. two pin gimbal joint (1). movement of supported structure can be achieved virtually to any point on the top half surface of the sphere.

The above explained components (2) and (3) are manufactured using structural grade aluminum alloy which makes it lightweight. Further, the components are simple to fabricate, easy to transport as lightweight and easy to assemble or dismantle at site finds it most suitable to be used as structural hinge in the guyed mast of temporary support structural system for power lines. For other systems explained above, the two pin gimbal joint (1) components may be designed using the different materials desirable in the particular system. The simple construction makes two pin gimbal joint (1), a cost effective structural/mechanical hinge with wide range of applications.

Although the invention has been described in detail herein, it should be understood that the invention is not limited to the embodiments herein disclosed. Various changes, substitutions and modifications can be made thereto by those skilled in the art without departing from the spirit or scope of the invention as described and defined by the appended claims.

EXAMPLES

The following examples given by way of illustration of the working of the invention in actual practice and should not be construed to limit the scope of the present invention in any way.

EXAMPLE- 1

Based on the typical assembly/configuration of two pin gimbal joint numerical results and analytical equations are derived to design its components. The gimbal joint and its components are designed for the various probable failure modes that occur in an actual system under applied loads and their combinations which will occur during its service life. Figure 4 shows the test setup for compression test carried out using a 2500 kN universal testing machine to study the behaviour of two pin gimbal joint under compression load and to evaluate its compression load carrying capacity for the comparison with analytical/numerical estimates. The various components of the joint were instrumented using foil type strain gauges and responses were monitored during the test. The observed responses were well within the limits and as expected linear up to the elastic limit. The test load carrying capacity was in good agreement with the numerical and analytical estimates.

Different qualification criteria’s such as gimbal articulation test, gimbal compression test and gimbal transverse test are suggested in IEEE 1070 standard for the gimbal joint used in temporary support structural system for power lines. Figure 5 shows the schematic of gimbal articulation test which specifies test on minimum rotation requirement i.e. rotation of support structure in 360° about vertical axis with an inclination of 45°. Since the present invention facilitates movement of supported structure virtually to any point on top half surface of sphere, the developed gimbal joint qualifies the test. The test schematic and setup for gimbal compression test given in IEEE standard is in Figure 6 a and b respectively. The two pin gimbal joint connected to the bottom conical panel of guyed mast of a temporary support structural system is placed in a test frame and compression load indicated in schematic is applied using a 1000 kN capacity hydraulic actuator. The test specimen withstood the test load successfully and no distress was observed on any part of the joint.

Further, the gimbal transverse test as suggested in IEEE standard is carried out on the present invention, the test schematic and set up is shown in Figure 7 a and b respectively. For this test an assembly of foundation plate with box, two pin gimbal joint and bottom conical panel of guyed mast of a temporary support structural system is placed in a test frame such that the foundation plate, its box and bottom plate assembly of gimble joint will in right angle with the top plate assembly of gimbal joint, bottom conical panel and loading mechanism. The test load is applied using the 1000 kN capacity hydraulic actuator. The test specimen withstood the test load successfully and no distress or deformation was observed on any part of the gimbal joint or any part of test assembly.

EXAMPLE-2

Prototype test on temporary support structural system for an equivalent to 220 kV single circuit suspension type transmission line tower was conducted using the present invention i.e. two pin gimbal joint as a structural hinge. The guyed mast for equivalent system was erected on test pad and rigging was carried out using steel wire ropes for the application of test loads at various load points, At the tower end of load points, load cells were employed to monitor the test loads. The other ends of wire ropes were connected to hydraulic actuators for load applications. The loads cells were calibrated with the standard proving rings and real time digital control system. Further the real time digital control system is connected with the load cells and hydraulic actuators in servo control close loop circuit. The equivalent guyed mast along with the present invention was tested as per IS: 802 (Part III) - 1978 (Reaffirmed 2003) and IEC 60652: 2002 guidelines for the test loads derived using IS 802 (Part 1/Sec 1): 2015 for 220 kV voltage class. To maintain the initial stability and verticality of guyed mast the guy wire pretensions were kept at 5% of the breaking load of respective guy wire. The guy wire tensions were monitored throughout the test using load cells at anchor end and found to be in limits. The measured mast deflections are as expected and mostly linear throughout the test. Further, the stresses measured in different members of test structure were well within the limit of elastic range and there is no visible deformation/cracking/overstressing/buckling of any component observed or ovalisation of pin holes happened, of the two pin gimbal joint during and after the test. This is the main requirement of scalable and repeat use structure/component.

The results of experimental investigations indicated in above examples proved that all the envisaged objectives related to the invention are successfully achieved.

Advantages of the present invention

The main advantages of the present invention are:

1. Simple to fabricate and requires less hardware.

2. Compact and economically affordable system.

3. Usage of lightweight materials makes it easy to transport and handle.

4. Allows rotation of the supported structure at 360° in horizontal plane and 180° in vertical plane e.g. virtually movement to any point on top half surface of sphere

5. It’s a cost effective solution to its closest prior arts.

6. It is easy to assemble and dismantle at site.

7. The components of the assembly of the system represented in present invention are analyzed and designed using finite element software and the assembly is proof tested for the qualification criteria’s as per the IEEE 1070 standard,

8. A prototype of temporary support structural system equivalent to 220 kV single circuit transmission line tower along with the two pin gimbal joint is tested for the design loads calculated as per IS 802 (Part 1/Sec 1): 2015 and the test carried out as per IS: 802 (Part III) - 1978 (Reaffirmed 2003) and IEC 60652:2002 standards.

9. The structural performance of this system is monitored for long term (more than 3 years) along with a demo structure installed simulating temporary support structural system equivalent to 400 kV double circuit transmission line suspension type tower confirming to IS 802 (Part 1/Sec 1): 2015 and CBIP Manual on Transmission Lines Publication No. 323, July 2014.