Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1999-10-12
2001-03-20
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S323120, C310S323190, C310S346000
Reexamination Certificate
active
06204592
ABSTRACT:
BACKGROUND OF THE INVENTION
This present invention relates to a ultrasonic nailing and drilling apparatus for nailing and drilling. More particularly, this present invention relates to toward a highly efficient and effective ultrasonic nailing and drilling for various precision use, such as medical or dental surgery. However, although the present invention is specially adapted as a medical device, but its application is not limited to the medical field.
Surgical procedures involving the use of an ultrasonic probe for removing tissue are well known. Various ultrasonic probes having operative tips that are caused to vibrate at frequencies between about 30,000 Hz and 60,000 Hz with a stroke of about 20 &mgr;m to 150 &mgr;m are applied depending on its usage for industrial or medical purpose.
For conventional drilling method, material and drill bits are stuck with each other thereby resulting in more friction. In addition, their effectiveness and efficiency has yet to be improved. That is, it is necessary for a drilling machine to generate a lower speed at high torques but torque versus speed characteristics in known electrical motors do not meet the requirements for such precision works.
When a drilling bit is turned (resonated) by ultrasonic wave and rotated by a power train such as motor, it will be more effective. The drill bit is almost floated from material (not stuck with each other) because of its rotational speed and longitudinal amplitude (stroke) both of which can be adjusted to each other so as to create the best efficiency. Moreover, certain drilling bits can be nails. When it is fully plugged into a material, it also can be removed by a machine tool due to reversed rotation. In addition, it can be used as anchor preparation. It can drill a small hole where anchor can be nailed tightly into a bone or other material.
Similarly, in ultrasonic drilling, although the drilling was useful to drill into hard materials, such as boron carbide, glass, titanium carbide, steel, bone, and the like, the drill itself was limited to chipping away the surface with a tubular drill bit. However, it has been very impractical to drill a deep hole, even with the diamond tipped drill bit, as the material became harder and as the chipped away materials were trapped within the hollow bit.
Therefore, it is an object of this invention to provide a ultrasonic nailing and drilling apparatus that not only impart vertical impact on the material, but also a rotational force simultaneously upon the material through the bit.
Also, it is another object of the invention to rapidly drill holes or nail into hard surfaces without undue mechanical or thermal stress to the bit or the material. Moreover, it is an object of this invention to be able to use various nails and drilling bits, including drilling bits similar to conventional drill bits.
It is also another object of the invention to make the use of the present invention simple and the device small enough to be held in a single hand of the user. Moreover, it is also desired that bits can be easily changed without much downtime or difficulties.
Additional objects, advantages, and novel features of the present invention will be set forth in part in the description that follow, and in part will be apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
SUMMARY OF THE INVENTION
To achieve the foregoing objects and other objects, and accordance of the purpose of this invention, as embodied and broadly described herein, a highly efficient and effective ultrasonic nailing and drilling apparatus for various precision use, such as medical (bone) surgery, comprises of a piezoelectric transducer means to give an axial thrust and a motor to give a rotation to a bit.
The ultrasonic nailing and drilling apparatus further comprises an elongated horn. Either exponential horn or stepped horn can be used depending on purpose. The exponential horn has low Q (quality factor) and wider resonating frequency range. The stepped horn has high Q and high gain (amplitude) which can be measured by surface ratio of a front area of horn, a rear area of horn and a shape of horn.
The piezoelectric transducer means is a source of a mechanical longitudinal stroke to the elongated horn which amplifies and transmits the amplified mechanical axial stroke to the operative tip. Here, the length of the elongated horn is determined by [&lgr;(2n+1)]/4 (&lgr;=wave length, n=0, 1, 2 . . . ) from a nodal point to maximize the amplitude to its highest stroke.
This ultrasonic nailing and drilling apparatus combines the best of the ultrasound nailing or drilling bit and the best of the rotational drill. Moreover, although the present invention is specially adapted as a medical device, but its application is not limited to the medical field.
The ultrasonic nailing and drilling apparatus further comprises of an elongated horn. The elongated horn has two ends, a first horn end and a second horn end. The first horn end forms an operative tip, wherein a bit can be fixedly attached. The operative tip can be in any form designed to for ultrasonic machines, and even can be in a similar shape as a flat screwdriver tip, as a Phillips head tip, or even as a conventional drill bit. However, the bits should be made of a high strength material such as a stainless steel and a titanium alloy.
The ultrasonic nailing and drilling apparatus further comprises of a shroud that houses the piezoelectric transducer means. The piezoelectric means is generally a ceramic piezoelectric transducer, but other piezoelectric transducer can be used. The piezoelectric transducer means should have an axial bore, and wherein the second horn end of the elongated horn extends through the axial bore of the piezoelectric transducer means. The second horn end of the elongated horn extending through the axial bore helps to transmit the vibration of the piezoelectric transducer means to the elongated horn; thus to the operative tip.
The ultrasonic nailing and drilling apparatus further comprises of a housing, wherein the shroud is rotatably attached within the housing. The piezoelectric transducer means and the elongated horn are fixedly attached within the shroud, but the elongated horn and the operative tip extend out of the shroud. The shroud should be able to freely rotate within housing. For the best performance, the housing should be a self lubricating bearing so the shroud can rotate nearly frictionless within the housing.
For better performance of the ultrasonic nailing and drilling apparatus, housing can comprises of a horn cover and a house bearing. The horn cover has a first cover end and a second cover end, wherein the horn cover encloses a substantial portion of the elongated horn. The first cover end is located toward the operative tip, and the second cover end is fixedly attached to the house bearing. In this configuration, the house bearing is the portion of the housing that rotatably houses the shroud.
The motor has a rotating arm. The motor is fixedly attached to the housing, but the rotating arm is fixedly attached to the shroud so that the shroud rotates as the rotating arm rotates. Therefore, when the ultrasonic nailing and drilling apparatus is switched on, the piezoelectric transducer means is activated to give axial impulses on the elongated horn, and the rotating arm of the motor rotates the shroud (and the piezoelectric transducer means within the shroud) to give rotation to the elongated horn. Therefore, the piezoelectric transducer means exerts axial impulses on the operative tip and the rotating arm of the motor exerts a rotation on the operative tip simultaneously.
For a best performance the motor should be a ultrasonic motor that is able to rotate the rotating arm bi-directionally; both clockwise and counter-clockwise, according to the need of the u
Dougherty Thomas M.
Park John K.
Park & Sutton
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