Cutting – With means to monitor and control operation – Including means to correct the sensed operation
Reexamination Certificate
1999-12-22
2004-07-27
Goodman, Charles (Department: 3724)
Cutting
With means to monitor and control operation
Including means to correct the sensed operation
C083S210000, C083S211000, C083S282000, C083S361000, C083S367000, C083S368000, C083S370000, C083S421000, C083S422000, C083S466100, C083S486000, C083S886000
Reexamination Certificate
active
06766720
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention pertains to making precision cuts in catheters and guidewires. Specifically, a device for holding, advancing, rotating and then cutting a catheter or guidewire is provided which is able to manipulate the catheter or guidewire in two degrees of freedom to enable precision control of the location of the cuts. Various clamping mechanisms are provided for manipulating the catheter or guidewire, as well as mechanisms for wear detection of saw blades and depth of cuts are used to make the cuts resulting in controlled variation in mechanical properties.
2. State of the Art
Making cuts in catheters and guidewires requires precision in order to ensure reliability because of the medical applications in which they are used. However, it is also important to control costs of production so that costs to the health care industry can be minimized.
The state of the art is typified by such devices as grinding wires, wound coils, and lasers for making the cuts. Electro Discharge Machining (EDM) is also used. Unfortunately, these devices often suffer from high cost or imprecise or difficult control mechanisms for properly positioning both the device to make the cut and the cylindrical object to be cut. With these devices it is also difficult to control the depth of cut, especially as wear increases on the cutting apparatus.
What is needed is a method and apparatus for making cuts in catheters and guidewires which allows precise control of characteristics of the cuts. This entails precision holding, advancement and rotation of the generally cylindrical object while at least one saw blade is itself advanced to make the cut and retracted afterward. A system is also needed which allows for highly precise detection of the point of contact of the blade and the cylindrical object, thus allowing precise control of the depth of cut and detection and correction for slight shape defects in the cylindrical object and wear of the blade.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and apparatus for forming precision cuts in catheters and guidewires.
It is another object to provide a method and apparatus for forming precision cuts in cylindrical objects.
It is yet another object to provide a method and apparatus for forming precision cuts by manipulating a cylindrical object in two degrees of freedom to control the parameters of the cuts.
It is still another object to provide a method and apparatus for holding, advancing and rotating a cylindrical object to be cut.
Still another object of the invention is to provide a method and apparatus for increasing throughput of a device which forms cuts in cylindrical objects by providing multiple saw blades on a single cutting tool.
It is another object to provide a method and apparatus for detecting the extent of wear of a saw blade in order to more precisely control the position of the saw blade.
It is still another object to provide a system which precisely detects the point of contact between the cutting blade and the cylindrical object, so as to correct for blade wear and for shape defects in the cylindrical object.
It is yet another object to provide a system for precisely measuring and controlling the depth of cut.
These and other objects of the present invention are realized in a preferred embodiment of a device for making cuts in a catheter, guidewire or other cylindrical object. The device includes a base which has at least one circular saw blade mounted on a spindle member, and a clamp for manipulating and positioning the object to be cut. The circular saw blade is rotatably mounted on the spindle member. The spindle member is free to move vertically and horizontally with respect to the base to thereby control the location, length, depth and angle of the cuts in a cylindrical object disposed adjacent thereto. The clamp is able to hold the object to be cut, as well as position it by, for example, rotation to thereby expose the entire circumference of the cylindrical object to the saw blade. By releasing the clamp, a pinch roller advances the cylindrical object before the clamp is re-engaged to securely hold the cylindrical object for cutting.
Another aspect of the invention is the ability to make precision cuts by providing means for controlling the rotation and advancement of the object to be cut and movement of the saw blade spindle member. Sensors are also provided to enable detection of wear on the saw blade so as to signal needed replacement or adjustment of the location of the saw blade spindle member to compensate.
Another aspect is the ability to simultaneously make a plurality of cuts in the object. This is accomplished with a saw blade having a plurality of blades in parallel. Even more cuts can be made by providing more than one saw blade spindle member, where each is independently movable in two degrees of freedom.
Another aspect of the invention is to provide more than one spindle member so that blades can simultaneously make precision cuts at different locations along the length of the cylindrical object.
Another aspect of the invention is to provide a system for electrical detection of contact and/or proximity between the cutting blade and the cylindrical object. The cylindrical object is grounded, while an electrical potential, either AC or DC, is applied to the blade and detected by a controller. When the blade contacts the cylindrical object, the electrical current detected by the controller jumps because of the ground connection, allowing the controller to very accurately detect the point in the blade's travel where contact occurred.
Another aspect of the invention is to provide a system wherein the electrical proximity/contact detection system is employed at a plurality of points around the circumference of the cylindrical object, so as to detect flaws in the shape of the cylindrical object, and to correct the depth of cut accordingly in order to produce a catheter/guidewire with the desired characteristics.
These and other objects, features, advantages and alternative aspects of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description taken in combination with the accompanying drawings.
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Davis Clark C.
Jacobsen Stephen C.
Goodman Charles
Sarcos LC
Thorpe North & Western
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