German IHG springs IHG models IHG prices

IHG springs are a special type of extension spring, suitable for applications with large elongation and non-increasing load. Constant-force springs consist of spiral metal strips; the inner side of the strip is curved so that each coil wraps tightly around the inner coil. When the metal strip is stretched (twisted), internal stress resists the load force, just like a standard extension spring, but the spring rate is nearly constant (zero). See the load/torsion diagram. In use, an ID is typically used to wind this spring tightly onto a drum, with its free end connected to the load, similar to a counterweight. However, it can also be reversed, with the free end fixed and the spring itself providing the working force, similar to carbon brushes in electrical devices.

IHG spring installation and removal

Hydraulic hand pallet trucks are widely used in production. During maintenance of their pressure oil pumps, we found that the pressure spring responsible for returning the pump piston rod and the truck's pressure arm is difficult to install and remove. Its wire diameter is n, and it stores an elastic force of up to 1000N. This often delays troubleshooting and directly affects production schedules. Previous measures yielded poor results. Therefore, I designed the pressure spring installation/removal tool shown in Figure 1. The tool consists of a lower pressure lever 1, pressure blocks 10, connecting pins 14, nuts 1, spherical washers 12, upper pressure lever 13, positioning sleeves 16, and levers. To operate, rotate the nut 11 to the appropriate position so that the cylindrical head claw of the lower pressure lever 1 contacts the truck body 2. The two pressure blocks 10 press symmetrically on the washer 6. Rotate the compression nut n to pull the tie rod 15, causing relative movement between the upper pressure lever 13 and the lower pressure lever 1, thereby compressing the pressure spring. When the washer 6 clears the cylindrical pin 7, the pressure wheel shaft 9, pressure wheel 8, and cylindrical pin 7 can be removed. Then, loosen the nut 11, remove the installation/removal tool, and take out the pressure spring to disassemble, inspect, and repair the pressure oil pump. The positioning sleeve 16 on the tool is a critical component. During manufacturing, one end features an internal spherical surface with a slot-shaped hole in the middle, and the other end has an inclined flat surface. It forms an interference fit with the pressure lever. It must make good contact with the spherical washer 12 and the ball head of the lever 15. The pressure block 10 and connecting pin 14 have a clearance fit to ensure flexible rotation. The connecting pin 14 and upper pressure lever 13 have an interference fit. The connecting shaft 18 and pressure lever have a clearance fit.

IHG spring rebound control measures

1) Select materials with good bending performance: Using materials with low yield limit and high elastic modulus as bending parts can achieve higher bending quality. In addition, the thickness tolerance of the blank, surface quality, and flatness significantly affect bending rebound. For workpieces with high bending precision requirements, the quality of the blank in these aspects should also be screened. 2) Select a smaller relative bending radius: A small r/t value indicates a high degree of deformation. Generally, when r/t ≤ 3-5, it is considered that the bending zone of the sheet metal has fully entered the plastic state. A smaller bending radius helps reduce rebound, but an excessively small radius may cause cracking in the bending zone. The minimum bending radii provided in references are mainly empirical data and can serve as a reference for sheet metal designers. 3) Select the required die gap: For V type bending, the gap value is achieved by high-speed machine tools and is independent of the die itself. For U type bending, rebound decreases as the die opening depth increases and as the die gap decreases. For workpieces requiring high bending precision, the single-side bending gap can be set to Z = t; if higher precision is needed, bending with slight thinning is more effective in reducing rebound. Because zero or negative gap bending changes the stress state of the sheet metal, converting ordinary bending into draw bending, the inner side of the neutral layer of the blank is under compressive stress, so the entire cross-section of the blank is under tensile stress in the tangential direction. After unloading, the rebound of the inner and outer fibers cancels out, reducing rebound (Figure 4). Therefore, using draw bending processes and dies with adjustable gaps is beneficial for controlling rebound. 4) Design reasonable workpiece shapes: U type bent parts have less rebound than V type parts. Complex workpiece shapes involve more mutual constraints between parts, making rebound difficult. Therefore, ? type rebound is smaller than U type. If suitable reinforcing ribs are pressed at the bending location, rebound is further reduced. Therefore, flanging or hemming bending parts can both increase stiffness and reduce rebound. 5) Adopt appropriate microstructural states: Materials after cold working hardening have large bending rebound. For bending parts with high precision requirements, if the blank has cold work hardening, it should be annealed before bending. Where necessary and permissible, heating the blank during bending can eliminate rebound for thicker blanks. The rebound angle in corrected bending is significantly smaller than in free bending, and the greater the correction force, the smaller the rebound. 6) Correct the punch shape for bending: This is because the correction bending force concentrates the punching force in the bending deformation zone, forcing the inner metal layer to be compressed. After the sheet is corrected, both inner and outer fibers are elongated and will shorten after unloading. Since the rebound trends of the inner and outer layers are opposite, the rebound amount is reduced, thereby overcoming or minimizing rebound. Thus, corrected bending is a bending method similar in nature to draw bending, with a wider application range. Generally, the punch for corrected bending adopts the shape shown in Figure 5.

IHG spring functions and applications

1) Reset function: Springs deform under external force and return to their original state when the force is removed. Many tools and devices utilize this property for resetting. For example, reset springs are installed on the hinges of many building doors, allowing them to automatically reset after people pass through. This function is also used in automatic umbrellas, mechanical pencils, and other convenient items. In addition, various buttons and keys require reset springs. 2) Drive function: Mechanical clocks and wind-up toys are driven by tightening the mainspring. When the mainspring is tightened, it undergoes bending deformation and stores elastic potential energy. Upon release, the elastic potential energy converts to kinetic energy, driving rotation through the transmission mechanism. Toy guns, starting pistols, and military firearms also operate based on this spring property. 3) Buffering function: Springs are installed between the frame and wheels of locomotives and automobiles to use elasticity to reduce vehicle vibration. 4) Vibration and sound generation function: When air flows through the reed holes of harmonicas and accordions, it impacts the reeds, causing them to vibrate and produce sound.

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