GB2456024A

GB2456024A - An assembly jig for rebar cages

Info

Publication number: GB2456024A
Application number: GB0814337A
Authority: GB
Inventors: Ron Packman
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-12-29
Filing date: 2008-08-05
Publication date: 2009-07-01
Also published as: GB0800639D0; GB0814337D0; GB0725375D0

Abstract

An assembly jig arrangement for rebar cages comprising supporting trestles bearing a plurality of movable clamps 3, 6 carrying reinforcement support frames 4, where the clamps selectively retain template elements 5 adjacent to the reinforcement support frames, the clamps and templates each bearing co-operating attachment features thereon, to accurately position the template to define a predetermined configuration of longitudinal reinforcement rods in a cage structure. The assembly jig will permit safer and quicker assembly of rebar cages. With the templates in position the operatives may then assemble the rebar cage with minimum reference to the engineer's drawings.

Description

A Jig for the Assembly of Rebar Cages for Reinforced Concrete

Description

The cages of reinforcing steel (rebar cages) that give strength to reinforced concrete are designed by structural engineers and set out on complex diagrams for the contractor to assemble.

The contractor will usually assemble the reinforcement bars into a cage with reference to a drawing and with the bars supported freely on an arrangement of trestles.The spacing of the reinforcing bars is set out using chalk marks on the bars and the whole assembly is held together with light gauge tying wire'. As the cage has more and more elements added to it becomes progressively more rigid, but at the outset the assembly can be flexible and imprecise.

The invention described herein is in the first part a more rigorous means of assembling a reinforcing cage by the creation of a purpose built Assembly Jig, and in the second part a means of forming reinforcement cages on the Assembly Jig using a system of templates that are derived from the design engineers drawings.

Thus according to the present invention, there is provided an assembly jigusinga rigid base to support fixtures that in turn support the steel reinforcement components that are to be fixed together. The jig is able to accommodate a wide variety of different reinforcement cages and permits a safer, more speedy and accurate assembly of reinforcement cages.

The basis of the assembly system is the base', which is a rigid bench or beam or column that is able to have support fixtures attached to it along its length. It could equally be based on a firm floor or slab that is accurate and strong enough to accept the loads entailed. Support fixtures are capable of being positioned along the length of the base at intervals that relate to the reinforcement cage to be buil1, or at a convenient repeating interval if the fixtures are to be non-moveable.

The support fixtures in turn support an adjustable rigid framework that is capable of holding the reinforcing bars in their correct relationship one to the other so that their positions may be checked and confirmed. When the positions of the rebars are correctly adjusted the entire assembly may be fixed together using whatever means preferred and then removed from the assembly.

In its basic form the assembly jig makes the process of assembling a reinforcement cage a more speedy and accurate process. However the invention is also capable of receiving templates that define the position of the various rebars without resort to measurements.

The templates used to form a reinforcement cage may either be disposable or of a material that may be allowed to remain in the concrete after it has been poured. If left in 2.

the concrete, the template may form part of the reinforcement of the beam, and may indeed be manufactured from steel sheet or reinforcing bar.

The invention is shown on the attached figures one to six.

Figure I shows the typical cross section of a reinforced concrete element, where the outline of the concrete has set within it the required airangement of rebars. Alongside this cross section is a typical template that may be used on the Assembly Jig to facilitate the location of rebars in the framework.

Figure 2 shows the Assembly Jig base member with one of the support fixtures (i.e. a clamp unit) in place. The clamp unit is shown with the adjustable support framework fixed in position. There may be any number of clamp units used on any given base member, but typically three to six clamp units may be used. The clamp unit shown may be moved along the length of the base member and then fixed in the required position.

Alternatively there may be a plurality of clamp units or support fixtures fixed at intervals along the length of the base member. The clamp unit holds a framework that is used to support the rebars in their designated positions so that they may be rigidly fixed to each other with accuracy. The framework is adjustable to suit the arrangement of the rebars required. It may be left in place within the rebar cage when it is lifted from tl jig for transport to site, or left behind and adjusted to receive the next rebar cage. The diagram also shows the means of positioning a template to one of the clamp units to facilitate the positioning of the rebars. The template is a full size derivatiw of the engineering drawing and has slots that receive the rebars and hold them on the supporting framework in their correct positions. Each slot may be marked with the identifying code of the rebar it receives. The fixing of the template to the clamp unit can be polarised, as shown, so as to prevent incorrect assembly.

Figure 3 shows one of the clamp units fitted with an adjustable support framework and a template, and ready to receive rebars. It is positioned at the appropriate point along the length of the base member, as informed by the engineer's drawings or description. Once all of the required clamping units are in position the assembly of the rebar cage may begin.

Figure 4 shows a base member with three clamp units in place. Each clamp unit is equipped with a template as described previously.

Figure 5 shows the completed rebar cage assembled on thejig and ready to have all of the elements fixed to each other using tying wire or some other form of fixing.

It is important to note that the jig may be used without the templates whereby the operatives will work from an engineers drawing as in the traditional manner.

FIGURE 1 1. During the Engineering design stage the basic outline of the required beam is drawn. This then provides the basis for the template. It is then sent to a fabricator who will cut out the required templates set for each location along the length of the beam.

2. The template is then sent to site along with the reinforcement for assembly into a reinforcement cage.

FIGURE 2 Typical template made from thin plywood, MDF or similar sheet material with appropriately sized holes as shown in Figure 1. These figures represent the actual locations of the reinforcing bars together with a unique template identifier.

3. Main clamp unit. This is able to move along the bench or steel section to its appropriate location and secured accurately in place.

4. Reinforcement support fixed to main clamp unit. This takes the weight of the bars and is demountable upon completion of fixing the reinforcement.

5. Template clamped into holding frame on main clamp unit. This will allow the template to be fixed accurately for fixing of reinforcement.

6. Front holding frame clamp. This block that will hold the templates in place. The circle and rectangle slots enable ease of fixing to avoid confusion.

FIGURE 3 6. Once the template has been securely fixed into the clamp system it can then be positioned on the bench/section to the required location as specified on the template.

*:*::* 7. This same procedure is then carried out for all the templates within the required beam length. * * ****

FIGURE 4 8. Reinforcement can now be fixed in place to suit require holes as formed on template. S... * *....

* FIGURE 5 : 9. Continue with fixing all required reinforcement bars until beam reinforcement complete.

e 10. Once reinforcement complete the template can be removed.

*:5. 11. Unsecure the reinforcement cage from the clamping system and crane into place in pre-dug trench in the ground ready to be concreted.

12. This whole process can then be repeated for all required site beams, using various templates from the design stage. 4.

Claims

Claims For the Assembly Jig used with or without templates.

1. The invention allows safe assembly of reinforcement cages without distortion of the cages under their own weight.

2. The invention may be set at a working height that suits the individual operative.

3. The invention allows accurate repetition of any given rebar cage using the same settings for the clamps and adjustable support frames.

4. The invention allows for the assembly of rebar cages in a wide variety of sizes and lengths.

5. The invention allows the completed rebar cage to be lifted directly off of the jig using crane or lifting vehicles.

6. The invention may be moved from place to place within a site to follow the work programme.

7. The demountable trestles allow for easy relocation of the invention to different sites.

8. The invention allows for additional clamp units to be positioned so as to receive rebars that will be fixed into intersecting rebar cages For the Assembly Jig used with Templates.

9. The invention translates the engineer's intentions directly into templates for the creation of a rebar cage without the need for interpretation or coordinatbn, thereby eliminating a source of error.

10. With each template given a unique identifier within the project documentation the possibility of using incorrect information is reduced.

II. The use of a fully templated work space allows more speedy assembly of rebar cages.

12. The use of a fully templated workspace allows safer working conditions for operatives.

13. With the templates left in place the rebar cage is more rigid for the rigours of transportation.

14. With the template system left in place it can form the basis ofconstructing the formwork around the cage.