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Introduction to construction and application of cold extruding connection for steel bar sleeve
Edit:Ningbo Okeer Machinery Technology Co., Ltd.   UpDate:2018-04-25

The cold extruding connection of steel bar sleeve is a new technology of reinforcing bar connection in the construction of reinforced concrete structure. Several large hydroelectric projects have been built and constructed in China, which are widely used in the Three Gorges Hydropower station, Xiaolangdi project, Gongboxia Hydropower station and Laxiwa diversion tunnel. At present, in order to make this new construction technology in the LAXIWA project reasonable use, the following on the steel sleeve cold extrusion technology for some brief introduction.

 

1. Characteristics of cold extrusion technology of steel sleeve


(1) The cold extruding connection technology of steel sleeve is simple and easy to master.

(2) The cold extruding connection technology of the steel sleeve is fast, and the traditional welding method can save a lot of time in the construction.

(3) The cold extruding connection technology of the steel sleeve can lower the engineering cost than the traditional steel welded joint construction.

(4) The cold extruding connection technology of the steel sleeve is applicable to the radial extrusion connection of ribbed steel bar with φ16-φ40 steel bar diameter in the reinforced concrete structure.


2. Technical requirements for cold extrusion of steel sleeve

It is necessary to adopt suitable extruding process and reasonable acceptance standard in the construction of extrusion connection of ribbed bar to ensure that the quality of construction meets the design requirement completely. The specific use of this technology should be in line with the "gb1499-91", "gb13014-91" "GBJ10-89", "gb50204-92", "gb8162-87", "jgj107-96", "yb9250-93" and other normative requirements.


The cold extrusion connection method is a kind of mechanical connection method, which is put on the steel pipe at the end of the two steel bars to be connected, and then squeezed by a portable hydraulic press, so that the casing is deformed and two steel bars are connected together into one. This method is suitable for industrial and civil Construction (construction), high-rise building, foundation engineering, etc. All kinds of reinforced concrete structure of Φ20~40ⅰ, Ⅱ grade steel joints and different diameter rebar joints, ribbed bar connection can connect vertical, horizontal and any inclination of the steel bar, its joint strength, stiffness, toughness uniformity and the base material is equal.

I. Material

The ⑴ ribbed bar conforms to the gb1499-91 standard of reinforced concrete.

⑵ casing material conforms to gb5310-85 standard.

Mechanical equipment

The complete equipment of the steel bar extruding connection is composed of the extruding connection clamp, the ultra-high pressure electric pump, the ultra-high pressure tubing, the hanger (manual hoist) and so on.

The steel bar Extrusion clamp has yj~40 type extrusion clamp, used for butt-φ40~36 ribbed bar, yj~32 type extrusion clamp, for φ32~20 ribbed bar butt, yj~23 type extrusion clamp, for φ25~18 ribbed steel bar docking.

Operating conditions

⑴ before pressing to remove the steel sleeve and rebar crimping parts of rust, oil, mud sand, etc., the end of the steel bar to be straight, if there is bending, it must be straightened.

⑵ hydraulic system is strictly prohibited to mix impurities, when the connection is removed over the hose, its end should be kept good, can not stick to dust sand.

  

Ii. Operation Process

Extrusion process and Sequence

The steel bar extrusion connection is divided into two steps.

The first process is to first on the ground in each to be connected to the end of the bar in accordance with the required half of the casing pressure.

The second process is to squeeze half of the joint of the steel bar into the already waiting for the end of the bar, and then press the squeeze clamp, so that the entire joint extrusion work.

The extrusion joint must be extruded from the middle of the sleeve to the end in order of marking.

Semi-joint connection technology of reinforcing steel bar

The first process described above is as follows:

⑴ installed high pressure tubing and steel bar with a limiter, casing die, and in the die also coated with lubricating oil;

The ⑵ presses the hand to control the switch, causes the casing to the positive pressure mold inside hole, then presses the hand off switch;

The ⑶ is inserted into the reinforcing bar to the position-limiting device.

The ⑷ presses the hand to control the switch, carries on the extrusion;

⑸ when you hear the overflow sound of hydraulic oil, then press the hand-controlled switch, return the plunger, remove the die;

⑹ Remove the half casing connector and end the half joint extrusion operation.

Extrusion process of steel bar

The second procedure mentioned above is as follows:

The ⑴ is inserted into the steel bar of the structure to be connected, and the extruder is seated;

⑵ placement of die and cushion for reinforcement;

⑶ according to the trigger control on the switch, to squeeze, when you hear the hydraulic oil issued overflow sound, according to the hands of the switch;

⑷ return plunger and guide plate, put on cushion block;

⑸ according to the start control on the switch, to squeeze;

⑹ according to the start control on the switch, return to the plunger and add cushion block;

The ⑺ presses the hand to control on the switch, carries on the extrusion, then presses the hand controls the switch to return the plunger;

⑻ Remove the cushion block, die, and remove the extruder, the steel bar connection is completed.


III. Quality Standards

Guarantee Project

⑴ steel material conforms to the gb1499-91 standard of rebar.

⑵ casing materials should be quality inspection orders and certification, geometric dimensions to meet the requirements.

⑶ continuous reinforcement joint strength must reach the same type of steel strength value, according to each type of connector, to each 500 for a batch (less than 500 are still a batch) for the tensile test, three consecutive unqualified, acceptance of the number of batches to double.


Basic projects

⑴ casing Joints After the length of the casing extrusion, did not reach the paint mark Line, error more than 5mm, will not reach the paint mark line of this end casing and steel welded together, the weld height must not be less than 5mm.

⑵ dosage gauge to check the outer diameter of the extrusion casing joint, pass that is qualified, otherwise unqualified, need to press mold again, squeeze again.

Iv. Precautions for construction

Avoid the common problems of engineering quality

Tool Sleeve BlanksThe geometrical size of the garbage bar joint position to meet the design requirements.

The connecting end of the ⑵ steel bar and the casing inner wall are not allowed to have oil, rust and silt; the grease outside the casing joint must be wiped clean.

The steel bar joint of the ⑶ pillar should be 1m higher than the concrete surface to facilitate the steel bar extrusion connection operation.

⑷ is not allowed to hit flat ribbed bar pattern.

The end of the ⑸ bar should be straight, if there is bending, it must be straightened.


Main safety technical measures

⑴ no hard pull wires or high-pressure tubing.

⑵ high-pressure tubing shall not be beaten to death.

⑶ to participate in the cold extrusion of the staff must be training, assessment, holding certificate.

⑷ operators must comply with the construction site construction work related regulations.

Product protection

Connect the finished product not to throw at random.