Constant force spring is used in removing an implanted object using laser cut hypotubes

source：Qianye Precision time：2022-9-14

Removal or extraction of the lead may be difficult. As mentioned above, the body’s natural healing process forms scar tissue over and along the lead, and possibly at its tip, thereby encasing at least a portion of the lead and fastening it even more securely in the patient’s body. In addition, the lead and/or tissue may become attached to the vasculature wall. Both results may, therefore, increase the difficulty of removing the leads from the patient’s vasculature.

A device for removing an implanted object from a body vessel, may comprise a sheath assembly comprising an outer sheath assembly and an inner sheath assembly, and a pin, the outer sheath assembly comprising an outer sheath and an outer band, the outer band coupled to the pin, the inner sheath assembly comprising an inner sheath and a tip, wherein the tip has a cutting surface, the inner sheath comprising a proximal end and a distal end, wherein the distal end of the inner sheath is coupled to the tip, the tip comprising a cam slot for receipt of and cooperation with the pin, and a handle assembly comprising a trigger and a barrel cam cylinder, the trigger comprising a trigger pin, the barrel cam cylinder comprising a barrel cam cylinder slot for receipt and cooperation with the trigger pin, wherein the proximal end of the inner sheath is coupled to the barrel cam cylinder such that upon the trigger pin moving proximally in a longitudinal direction, the barrel cam cylinder rotates in both a clockwise direction and a counter clockwise direction, thereby causing the tip to rotate in both the clockwise direction and the counter clockwise direction while the tip moves longitudinally.

As you can see from the picture an exemplary spring assembly 412 is depicted. The spring assembly 412 includes a constant force spring 472 and a spool 474. One end of the constant force spring 472 is connected to the spool 474, and the other end of the constant force spring 472 is connected to the post 440 extending from the trigger 408. As a clinician pulls the trigger 408 proximally, the sliders 432, 436 travel and slide in the grooves within the handle frame 404, thereby preventing the trigger 408 from moving vertically within the handle assembly 108 and only allowing the trigger 408 to move along the longitudinal axis of the surgical device 106 from its distal end toward its proximal end and/or vice versa. As the trigger 408 moves proximally, the constant force spring 472 uncoils, thereby creating tension and a distally directed force. Accordingly, when the trigger 408 is released by the clinician, the constant force spring 472 recoils and pulls the trigger 408 back towards its original and most distal position.

Constant force spring is made of steel strip. When it is straightened by external force, the spring will naturally roll back and produce elastic force. The advantages of constant force spring over traditional wire spring are as follows:

1.High elastic output can be achieved in a very small device space.

2.Maintain a certain elasticity in all strokes. The preload stroke is short, that is, the required elasticity can be achieved through a short stroke. The original long-term is smaller than the line spring, and the stroke is unlimited.

When designing or specifying a constant force spring, many basic engineering parameters need to be considered. Material, fatigue life, tensile load, torque and friction, speed and acceleration, installation, safety considerations and application environment are all key factors.

Shenzhen Qianye Precision Metal Co., Ltd. is a global spring manufacturer with more than 20 years of spring manufacturing experience. As a professional spring supplier, we can provide all kinds of spring springs, as well as the application design and solutions of all kinds of springs. We sincerely suggest that customers obtain consulting services from our R&D engineers at the initial stage of product introduction and development. Assist in product design, development and proofing according to your needs, so that your products can find the best solution to meet your application needs.