• Mechanical expansion bolts made of high-strength steel enables precise, displacement-controlled, radial and axial preloading

• Pre-tensioning using the proven HEICO-TEC® Tension Nut

• Designed to user specific requirements

• Operation from one side

• Selectable dimensions

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DESIGN AND FUNCTION

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The blind bore expansion bolt is suitable for applications in threaded blind bores. This blind bore expansion bolt is pre-tensioned using the proven HEICO-TEC® Tension Nut.

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The blind bore expansion bolt consists of four components: the longitudinally slotted conical sleeve, the conical bolt, a HEICO-TEC® Tension Nut and a clamping nut. Due to its size and weight, blind bore expansion bolts are not installed as one unit, but in individual parts. First, the tension nut is connected to the conical sleeve. Depending on the design of the blind bore expansion bolt, this can be done with or without a thread by means of a collar at the end of the conical sleeve. The conical sleeve including the tension nut is then pushed into the bore until the tensioning element rests on the coupling flange. Due to the slotted design of the conical sleeve, it has enough flexibility to be inserted effortlessly, even if the bores are slightly misaligned.

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The conical bolt is threaded on both ends. The conical bolt is inserted into the conical sleeve with the tapered side facing downward. Next, the clamping nut is fastened to the end of the conical bolt. The expansion of the conical sleeve is adjusted using a feeler gauge. A defined gap is set between the conical sleeve and the clamping nut, corresponding to the required distance to achieve the desired radial pre-tension. Then, the pressure bolts of the HEICO-TEC® Tension Nut are tightened. As a result, the slotted conical sleeve is pulled upward and expanded by the internal conical bolt. The expansion continues until the conical sleeve touches the clamping nut, at which point the radial expansion stops. Further tightening of the pressure bolts generates additional axial force, which clamps the coupling flanges together. This process allows tensile loads or bending moments to be transmitted, while also creating additional frictional contact in the joint, thus increasing the transmittable coupling torque.

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To disassemble the blind bore expansion bolt, first loosen the pressure bolts. Then tighten the clamping nut and release the conical sleeve from the conical bolt. The conical bolt, along with the clamping nut, is untightened. Thanks to the slots, the conical sleeve contracts and the HEICO-TEC® Tension Nut is easily removed from the bore with minimal effort.

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ADVANTAGES

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• Simple pretensioning using HEICO-TEC® Tension Nut

• Defined radial preload through strain-controlled tightening

• Axial and radial preload ensure maximum clamping force

• No additional costs for special tools or unnecessary reworking of bores and fitted bolts

• Simple assembly and disassembly

• Reusable