JP2018108223A - Medical drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical drill which can easily perform bone perforation and can reduce a load on a patient and a doctor.SOLUTION: A solid medical drill has two cutting blades symmetrical with respect to a rotation axis, has thinning applied to an end part, composes the cutting blades of a thinning cutting blade and a main cutting blade, forms a thinning surface into an almost radial shape inclined in a drill shaft core direction when seen from a drill front surface side, and has a groove length of a cutting chip discharge groove shorter than cutting depth of the bone to be cut. A hollow medical drill is provided with an inner cavity going through from an end in an axial direction, has a plurality of cutting blades at an end part, forms the end part into a ball shape or an elliptic spherical shape with respect to the axis direction seen from a vertical direction when rotating in the axial direction, provides the cutting blade with a relief angle on the back surface, provides a cutting chip discharge groove from an internal diameter end of the end part to an outer peripheral part, gives the cutting chip discharge groove a twist in an axial direction, which forms a rake angle on a cutting blade front surface, and provides a cutting blade end part with a gash pocket.SELECTED DRAWING: Figure 16

Description

  The present invention relates to a medical drill, and more particularly to a medical drill that is less likely to wear and that has an excellent cutting force.

  In order to ensure the drilling depth and direction during bone drilling in bone surgery, a relatively small-diameter guide pin is inserted in advance in the desired direction and depth under fluoroscopy, and the guide pin shaft is removed. Surgical techniques have been used to drill bones in the same direction and depth with a relatively large diameter hollow drill having an insertable diameter lumen.

In such a bone surgical operation, at the stage where the hollow drill is rotated to advance the bone drilling by extrapolating the guide pin that has been inserted and positioned in advance, the guide pin does not rotate and the original position, that is, the depth and direction are originally not rotated. In actuality, bone waste generated around the cutting edge of the hollow drill tip penetrates into the gap between the hollow drill inner surface and the outer surface of the guide pin. The friction between the surface and the guide pin increases.
As a result, the rotational torque of the hollow drill may be transmitted to the guide pin. In that case, the guide pin rotates with the hollow drill and excessively penetrates into an unexpected depth, which may damage important nerves, blood vessels, muscle tendons, organs, and the like.

  In order to avoid the guide pin rotating with the hollow drill and excessively penetrating to an unexpected depth, it is necessary to suppress the influence of the invading bone waste. For this reason, it is necessary to provide means for removing the invading bone waste from the gap toward the outer surface of the hollow drill.

For example, a bone drilling device disclosed in Patent Document 1 is known as a device that satisfies such a need.
The bone drilling device of Patent Document 1 has a guide pin for determining the direction and depth of bone drilling and inserting it in advance in the bone in advance, and a cutting blade at the tip, and the guide pin can be inserted in the axial direction from the tip. A hollow drill having a hollow formed therein,
The hollow drill has a structural feature in that it has a bone waste outlet hole that communicates the lumen with the outer surface of the drill.

About medical drills including what was indicated by patent documents 1, it is used for various operation methods for perforation of a plate fixation bolt etc. of a fracture part focusing on a human bone.
In the bone drilling device of Patent Document 1, since the guide pin inserted in advance in the bone is used only for positioning, no rotational force is applied.
Depending on the part of the human body and the surgical procedure, after drilling the target location with a thin drill in advance, it stays in the state at the completion of drilling without removing from the bone, and the drill is used with the thin drill (101) as a guide. In many cases, a hollow drill (102) having a hole diameter that is equal to or slightly larger than the outer diameter of the hole is drilled with a hole having a diameter larger than that of the thin drill (101) (see FIG. 24).

For example, in the case of drilling in reconstruction performed by anterior cruciate ligament tear,
(1) A small-diameter drill (diameter: about 1 mm to 3 mm, length: about 200 mm to 600 mm) shown in FIG. 25A is drilled from a predetermined drilling location to a target location.
(2) A hole for rotating the hollow drill and passing the reconstructed ligament while it is inserted into the inner diameter of the hollow drill (see Fig. 25 (b)) with the small-diameter drill held on the bone as it was drilled. Perforate. In this step, the small-diameter drill serves as a guide for hollow drilling (see FIG. 25C).

  In the conventional hollow drill, as shown in FIG. 25 (d), a straight cutting edge (103) is provided from the end of the inner diameter (hollow part) to the outer peripheral part, and the twist angle is set along the outer peripheral part. In order to provide a chip discharge groove (21) while forming a linear cutting edge (103) at the tip, an arc-shaped gash pocket (22) is provided to cut from the tip to the outer periphery. The blade (103) is created (see (d) of FIG. 25).

However, in this shape, although a straight cutting edge is created, a clear rake of the cutting edge exists only in the vicinity of the outer periphery of the outer circumferential groove, so this portion is easily worn and there is a problem with the cutting force. There is.
Furthermore, since the conventional small diameter drill has a high cutting resistance and has a problem with the cutting force, it is difficult to position the hole at the time of cutting, and there is a possibility that the hole is displaced from a desired drilling position.

Japanese Patent Laid-Open No. 2006-52382

  The present invention has been made to solve the above-mentioned problems of the prior art, and in a solid medical drill, a drill with reduced cutting resistance and improved cutting force is provided. For hollow medical drills, the shape of each cutting blade is determined, and based on that shape, two or more cutting blades are arranged on the circumference and hung from the inner end to the outer periphery. An object of the present invention is to provide a medical drill that is hard to wear and has excellent cutting force by improving the cutting ability of the cutting blade that is created.

The invention according to claim 1 is a solid medical drill for bone cutting having two cutting blades formed symmetrically about the rotational axis, and thinning the tip.
When the cutting blade is viewed from the drill tip side, a thinning cutting blade extending in a shape including a curve from the chisel edge toward the drill outer peripheral side, and a main cutting blade extending from the end of the thinning cutting blade to the drill outer peripheral end Become
When the ridgeline at the boundary between the thinning surface and the chip discharge groove formed by the thinning cutting edge is viewed from the front side of the drill, which is the opening side of the chip discharge groove, the base from the drill tip side with respect to the drill axis direction. As it goes to the end side, it is formed in a substantially U-shape inclined in the direction of transition from the thinning cutting edge side to the main cutting edge side,
The rake angle θ ₁ formed by the main cutting edge and the rake angle θ ₂ formed by the thinning cutting edge satisfy θ ₁ > θ ₂ > 0 °,
The tip angle is 30 ° to 110 °, the twist angle is 5 ° to 25 °,
It is related with the solid medical drill characterized by the groove length of the said chip | tip discharge groove | channel being shorter than the cutting depth of the bone to cut.

  The invention according to claim 2 relates to the solid medical drill according to claim 1, wherein the tip angle is 40 ° to 90 °.

  The invention according to claim 3 relates to the solid medical drill according to claim 2, wherein the tip angle is 45 ° to 55 °.

  The invention according to claim 4 relates to the solid medical drill according to any one of claims 1 to 3, wherein the twist angle is 15 ° to 20 °.

  The invention according to claim 5 relates to the solid medical drill according to any one of claims 1 to 4, wherein the drill diameter is 1 mm to 3 mm.

The invention according to claim 6 is a solid medical device having a lumen that penetrates in the axial direction from the tip, has a plurality of cutting blades on the circumference of the tip, and has a drill diameter that passes through the lumen. A hollow medical drill for cutting bone for expanding the diameter of a hole drilled by a drill,
When the hollow medical drill is rotated in the axial direction, the shape of the tip portion is spherical or elliptical when viewed from the direction perpendicular to the axial direction,
The cutting blade has a clearance angle on the back surface,
A chip discharge groove is provided from the inner diameter end of the tip portion to the outer peripheral portion,
The chip discharge groove has a twist with respect to the axial direction, whereby a rake angle is formed on the front surface of the cutting blade,
The present invention relates to a hollow medical drill characterized in that a gash pocket is provided at the tip of the cutting edge.

  The invention according to claim 7 relates to the hollow medical drill according to claim 6, wherein the cutting blade includes a straight portion from the inner diameter end of the tip portion toward the outer peripheral portion.

  The invention according to claim 8 relates to the hollow medical drill according to claim 6 or 7, wherein the number of the plurality of cutting blades is 2 to 6.

  The invention according to claim 9 is characterized in that the diameter of the lumen is 0.1 mm to 0.2 mm larger than the diameter of the solid medical drill according to any one of claims 1 to 5. The hollow medical drill according to any one of claims 6 to 8.

The invention according to claim 10 is a tip portion for cutting a workpiece,
A solid medical drill for bone cutting that is thinned at the distal end with a proximal end fixed to the rotary drive device,
Two plane portions are provided from the distal end portion toward the proximal end portion,
A tip angle is provided at the tip,
One or more thinning surfaces are formed at the tip,
The tip has a chisel at the center,
The one or more thinning surfaces are formed substantially parallel to the cutting edge from the center of the tip toward the outer periphery;
The present invention relates to a solid medical drill characterized in that a flank is formed on the opposite side of the rake face of the cutting blade formed on the one or more thinning surfaces.

  The invention according to claim 11 relates to the solid medical drill according to claim 10, wherein the tip angle is 40 ° to 90 °.

  The invention according to claim 12 relates to the solid medical drill according to claim 11, wherein the tip angle is 45 ° to 55 °.

  The invention according to claim 13 relates to the solid medical drill according to any one of claims 10 to 12, wherein a drill diameter is 1 mm to 3 mm.

  The invention according to claim 14 is the solid medical drill according to any one of claims 1 to 5 and claims 10 to 13, and the hollow according to any one of claims 6 to 9. The present invention relates to a medical drill set including a medical drill.

According to a fifteenth aspect of the present invention, (1) the solid medical drill according to any one of the first to fifth aspects and the tenth to thirteenth aspects is used, and the diameter of the solid medical drill is determined. Drilling a cortex of the bone with a solid medical drill tip at a predetermined position of the bone to drill a pilot hole;
(2) Using the hollow medical drill according to any one of claims 6 to 9, the solid medical drill is inserted in the axial direction from the distal end of the lumen of the hollow medical drill. While expanding the pilot hole with the hollow medical drill,
(3) A solid medical drill and a hollow comprising a step of removing only the solid medical drill from the enlarged hole, passing a tendon through the enlarged hole, and fixing both ends of the tendon to the bone. The present invention relates to a bone drilling method for reconstruction of a ligament using a medical drill.

According to the solid medical drill according to the first aspect of the present invention, the tip angle is 30 ° to 110 °, so that the drilling is performed even if the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is shallow. Drilling to a precise point can be performed without the tip of the drill deviating from the point to be made.
In addition, since the twist angle is 5 ° to 25 °, the bone can be smoothly drilled without causing cracks.
When the ridgeline at the boundary between the thinning surface and the chip discharge groove formed by the thinning cutting edge is viewed from the front side of the drill, which is the opening side of the chip discharge groove, the base end from the drill tip side with respect to the drill axis direction It is formed in a substantially U-shape that is inclined in the direction of transition from the thinning cutting edge side to the main cutting edge side, and is formed by the rake angle θ ₁ formed by the main cutting edge and the thinning cutting edge. When the rake angle θ ₂ satisfies θ ₁ > θ ₂ > 0 °, the cutting resistance can be greatly reduced as compared with the conventional medical drill, and the bone can be easily drilled. A medical drill can be provided. In addition, since the cutting resistance is reduced, the drilling accuracy is improved, the drilling time is shortened, the work efficiency is improved, and the drill life can be greatly extended. Furthermore, since the cutting resistance is greatly reduced, the processing heat at the time of bone drilling can be suppressed, and the necrosis of the bone tissue can be suppressed.
Furthermore, when the rake angle θ ₁ formed by the main cutting edge and the rake angle θ ₂ formed by the thinning cutting edge satisfy θ ₁ > θ ₂ , the apparent rake angle is reduced and the bone tissue is reduced. The amount of biting is reduced and the bone tissue is easily cut. Further, by setting θ ₂ > 0 °, there is no problem when θ ₂ is changed from 0 ° to minus (negative) (cutting resistance increases and sharpness is deteriorated).
In addition, since the groove length of the chip discharge groove is shorter than the cutting depth of the bone to be cut, the strength of the drill is higher than that of the drill having the groove length longer than the cutting depth. Therefore, when used as a hollow drill shaft (guide) during cutting with a hollow drill, the drill is not easily damaged and the hollow drill can be supported more stably.

  According to the solid medical drill of the second aspect of the invention, since the tip angle is 40 ° to 90 °, the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is further reduced. However, even if the contact angle is shallow (small) to about 45 °, it is possible to perform drilling to a precise point without the tip of the drill being displaced from the point to be drilled.

  According to the solid medical drill of the invention of claim 3, since the tip angle is 45 ° to 55 °, the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is very shallow. Even more specifically, even when the contact angle is shallow (small) to about 30 °, drilling to an accurate point can be performed without the tip of the drill being displaced from the point to be drilled.

  According to the solid medical drill of the invention of claim 4, since the twist angle is 15 ° to 20 °, the function of smoothly drilling without causing a crack in the bone is more sure. It becomes possible to demonstrate to.

  According to the solid medical drill according to the invention of claim 5, since the drill diameter is 1 mm to 3 mm, the pilot hole can be formed at an appropriate diameter and position without damaging other than the target portion.

  According to the hollow medical drill of the sixth aspect of the invention, when the hollow medical drill rotates in the axial direction, the shape of the tip portion is spherical or elliptical when viewed from the direction perpendicular to the axial direction. A spherical shape is formed, the cutting blade has a clearance angle on the back surface, a chip discharge groove is provided from the inner diameter end to the outer periphery of the tip, and the chip discharge groove is twisted in the axial direction. As a result, a rake angle is formed on the front surface of the cutting blade, and a gash pocket is provided at the tip of the cutting blade. Therefore, it is possible to provide a hollow medical drill that is hard to wear and that has a high cutting ability. . Thereby, bone drilling can be performed easily and the burden on the patient or doctor can be reduced.

  According to the hollow medical drill of the seventh aspect of the present invention, the cutting blade is provided with the straight portion from the inner diameter end of the tip portion toward the outer peripheral portion, and therefore the cutting blade is less likely to be worn and more cutting is performed. A hollow medical drill with high capacity can be provided.

According to the hollow medical drill according to the invention of claim 8, since the number of cutting blades is 2 to 6, a hollow drill having higher cutting ability can be provided.
In addition, a hollow drill having an appropriate cutting ability can be selected according to the cutting purpose.

  According to the hollow medical drill according to the invention of claim 9, the diameter of the lumen is 0.1 mm to 0 than the diameter of the solid medical drill according to any one of claims 1 to 5. Since it is 2 mm larger, it is possible to eliminate the complications when inserting the hollow drill and the shake of the hollow drill shaft, and to smoothly drill the bone.

  According to the solid medical drill of the invention of claim 10, two flat portions are provided, a tip angle is provided at the tip portion, the tip portion has a chisel portion at the center portion, and one or more thinnings are provided. The surface is formed substantially parallel to the cutting edge from the center of the tip toward the outer periphery, and a flank is formed on the opposite side of the rake face of the cutting blade formed on one or more thinning surfaces. Therefore, it is possible to provide a solid medical drill in which rotary cutting can be performed efficiently and the sharpness (cutting ability) at the center of the tip is greatly improved. Moreover, since cutting resistance can be reduced significantly, heat generation during bone cutting can be suppressed, and necrosis of bone tissue during bone cutting can be suppressed.

  According to the solid medical drill of the invention of claim 11, since the tip angle is 40 ° to 90 °, the contact angle of the drill with respect to the surface of the work piece (bone tissue) is further reduced. However, even if the contact angle is shallow (small) to about 45 °, it is possible to perform drilling to a precise point without the tip of the drill being displaced from the point to be drilled.

  According to the solid medical drill of the invention of claim 12, since the tip angle is 45 ° to 55 °, the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is very shallow. Even more specifically, even when the contact angle is shallow (small) to about 30 °, drilling to an accurate point can be performed without the tip of the drill being displaced from the point to be drilled.

  According to the solid medical drill of the thirteenth aspect, since the drill diameter is 1 mm to 3 mm, the pilot hole can be formed at an appropriate diameter and position without damaging other than the target portion.

  According to the medical drill set of the fourteenth aspect, the solid medical drill according to any one of the first to fifth aspects and the tenth to thirteenth aspects, wherein the cutting resistance is low and the cutting ability is high. The hollow medical drill according to any one of claims 6 to 9, wherein the cutting blade hardly wears and has high cutting ability. Thereby, bone drilling can be performed easily and the burden on the patient or doctor can be reduced.

  According to the bone drilling method for ligament reconstruction using the solid medical drill and the hollow medical drill according to the invention of claim 15, it is easier and more accurate than the conventional bone drilling method for ligament reconstruction. Since bone drilling can be performed, the burden on patients and doctors can be reduced.

It is a figure which shows the solid medical drill which concerns on 1st embodiment of this invention, Comprising: (a) is a top view (figure which looked at the drill from the front end side), (b) is a front view of a front-end | tip part. . It is the figure which looked at the solid medical drill which concerns on this invention from the left direction a little rather than FIG.1 (b). It is a figure which shows an example of the usage method of the solid medical drill which concerns on this invention. It is a figure which shows the other example of the usage method of the solid medical drill which concerns on this invention. It is a figure which defines a clearance angle. It is a figure which shows the angle which applies a drill to a grindstone at the time of thinning formation. It is a figure which shows the angle of a thinning. It is a figure which shows the cross section orthogonal to a thinning part. It is a figure which shows an example of the edge part shape of a rake face. It is a figure which shows the solid medical drill which concerns on 2nd embodiment of this invention, Comprising: (a) is a top view (figure which looked at the drill from the front end side), (b) is a front view of a front-end | tip part. . It is a figure which shows the solid medical drill which concerns on 3rd embodiment of this invention, Comprising: (a) is a top view (figure which looked at the drill from the front end side), (b) is a front view of a front-end | tip part. . It is sectional drawing which cut | disconnected the solid medical drill which concerns on this invention to the vertical direction (drill length direction) along the chisel, (a) is the solid medical drill which concerns on 1st embodiment, ( b) is a solid medical drill according to the second embodiment, and (c) is a solid medical drill according to the third embodiment. It is a figure which shows the solid medical drill which concerns on 4th embodiment of this invention, Comprising: (a) is a side view, (b) is a front view of a front-end | tip part. It is a figure which shows the solid medical drill which concerns on 4th embodiment of this invention, Comprising: (a) is an expanded side view of a chisel part provided with a curvilinear shape, (b) is a linear shape (gear shape). It is an enlarged side view of the chisel provided. It is a figure which shows the example of the grindstone shape for creation of the thinning cutting blade in the solid medical drill which concerns on this invention, and has shown the rotating end part (outer peripheral part) of the grindstone. It is a figure which shows the example of the grindstone shape for creation of the thinning cutting blade in the solid medical drill which concerns on this invention, and has shown the rotating end part (outer peripheral part) of the grindstone. When the hollow drill of 6th embodiment of this invention rotates to an axial direction, it is a figure which shows the front-end | tip part seen from the orthogonal | vertical direction with respect to an axial direction, Comprising: (a) is a shape of a front-end | tip part, ( (b) is an elliptical sphere whose tip is horizontally long (long in the width direction), (c) is an ellipsoid whose tip is vertically long (long in the axial direction), and (d) is a corner where the tip is corner R It is a figure which shows a mode that it becomes a shape. When the hollow medical drill which equips the cutting blade of 6th embodiment of this invention with a linear part rotated in the axial direction, it is a figure which shows the front-end | tip part seen from the orthogonal | vertical direction with respect to the axial direction, (a ) Is a spherical shape with a tip including a straight line, (b) is a horizontally long (long in the width direction) elliptical sphere with a tip having a straight shape, and (c) is a vertically long (shaft) with a tip having a straight shape. (D) is a diagram showing how the shape of the tip becomes a corner R shape including a straight line. It is a figure which shows the hollow medical drill of 6th embodiment of this invention, Comprising: (a) is the figure seen from the left direction rather than the front of the front-end | tip part, (b) is a top view. It is a top view which shows the hollow medical drill of 6th embodiment of this invention, Comprising: (a) is a drill which equips the front-end | tip part with 2 blades, (b) is a drill which equips the front-end | tip part with 3 blades, (c) is a drill with a four-blade at the tip, (d) is a drill with a five-blade at the tip, and (e) is a drill with a six-blade at the tip. It is a top view which shows the hollow medical drill which equips the cutting blade of 6th embodiment of this invention with a linear part, Comprising: (a) is a drill provided with two blades in a front-end | tip part, (b) is 3 in a front-end | tip part. (C) is a drill with four blades at the tip, (d) is a drill with five blades at the tip, and (e) is a drill with six blades at the tip. It is. It is a figure which shows a mode that a bone tissue is cut using the solid medical drill of 6th embodiment of this invention. It is a figure which shows the position shift test at the time of the drilling in the inclination state using the solid medical drill which concerns on this invention, and the conventional solid medical drill, Comprising: (a) is the solid of 1st Embodiment The figure which shows the test result using the medical drill of no, (b) is a figure which shows the test result using the conventional solid medical drill. It is a figure which shows the mode at the time of drill drilling in the reconstruction performed by anterior cruciate ligament tearing. It is a figure which shows the drill used in the reconstruction performed by the conventional anterior cruciate ligament tear, Comprising: (a) is a side view of a thin diameter drill, (b) is a side view of a hollow drill, (c) is a hollow drill. The side view which shows a mode at the time of drilling using a small diameter drill as a guide, (d) is the front-end | tip part enlarged schematic diagram of the side view of a hollow drill.

[Embodiment 1]
Hereinafter, a preferred embodiment of a medical drill according to the present invention will be described with reference to the drawings.
1A and 1B are diagrams showing a first embodiment of a solid medical drill according to the present invention, in which FIG. 1A is a top view (view of the drill viewed from the tip side), and FIG. 1B is a front view of the tip portion. FIG.

The solid medical drill according to the present embodiment has two cutting blades formed symmetrically with respect to the rotational axis, and the tip portion is thinned.
The cutting blade is a thinning cutting blade (1) extending in a shape including a curve from the chisel edge toward the outer periphery of the drill when viewed from the drill tip side, and a main extending from the end of the thinning cutting blade (1) to the outer periphery of the drill It consists of a cutting blade (2). In the illustrated example, the main cutting edge (2) extends linearly from the end of the thinning cutting edge (1) to the outer peripheral edge of the drill, but may extend in a curved line, It may extend linearly including a curved portion. This is common to the first to fifth embodiments of the present invention.
In the figure, (3) is a flank, (4) is a chisel, (5) is a rake face formed by the main cutting edge (2), (6) is a new rake face formed by thinning, (W) Is the chisel width.

In the solid medical drill of the first embodiment, the cutting edge length in the extending direction of the main cutting edge (2) is the length of the main cutting edge (2) (A), and the thinning cutting edge (1) When the length is (B), A>B> 0. However, in the present invention, 0 <A ≦ B may be satisfied.
By setting the length (B) of the thinning cutting edge (1) to be equal to or longer than the length (A) of the main cutting edge (2), compared to the conventional medical drill where A> B It may be possible to greatly reduce the cutting resistance.

  In the solid medical drill according to the first embodiment, the larger the ratio (B / (A + B)) of the length (B) of the thinning cutting edge (1) to the full length (A + B) of the cutting edge, the higher the cutting resistance. Since it may be reduced, the length (B) of the thinning cutting edge (1) may be lengthened and the length (A) of the main cutting edge (2) may be shortened. However, when the length (A) of the main cutting edge (2) becomes 0, the surface accuracy of the drilled hole is lowered, so that 0 <A is necessary. Preferably, it is set so as to satisfy R × 0.1 ≦ A with respect to the drill radius (R).

FIG. 2 is a view of the solid medical drill of the first embodiment as seen from the left slightly from the front.
And rake angle formed by the main cutting edge (2) (θ _1), rake angle formed by the thinning cutting edge (1) (θ ₂₎ is, θ _1> θ _2> 0 satisfy °. However, just below the chisel (4), θ ₂ ≈0 ° (θ ₂ <0 ° close to 0 °).
The rake angle (θ ₂ ) formed by the thinning cutting edge (1) is smaller than the rake angle (θ ₁ ) formed by the main cutting edge (2). Means that it becomes smaller (relaxes).
If the rake angle is large, the amount of the blade bite into the drilling target increases, so there is no problem when drilling a metal workpiece using a machine tool or the like. Human power is lost to the load, and as a result, it cannot be cut.
In the present embodiment, by forming the thinning cutting edge (1) so as to satisfy θ ₁ > θ ₂ , the apparent rake angle is reduced, and the amount of biting into the work piece (bone tissue) is reduced. It becomes to cut.

The reason why θ ₂ > 0 ° is that when the rake angle (θ ₂ ) formed by the thinning cutting edge (1) is changed from 0 ° to minus, the cutting resistance is increased and the sharpness is worsened. Incidentally, the conventional drill is thinned so that the rake angle becomes minus (negative) because the cutting edge tends to be chipped if there is a rake at the center.

The solid medical drill (including the solid medical drill according to the first to third embodiments) according to the present invention has a tip angle set in a range of 30 ° to 110 °.
If the tip angle is less than 30 °, the tip of the drill becomes distorted and the sharpness is reduced. If the tip angle exceeds 110 °, the drill is tilted so as to reduce the contact angle with the surface of the work piece (bone tissue). Then, the tip of the drill slips and tends to be displaced from the drilling point, and there is a risk of damaging the human body (nerve etc.) at the time of drilling, and the contact angle cannot be set shallowly below 55 °, and drilling into the bone is difficult Since the number of cases increases, either case is not preferable.
By setting the tip angle in the range of 30 ° to 110 °, even if the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is made shallow, specifically, the contact angle is made shallow to about 55 °. Even if it is (smaller), it is possible to perform drilling to an accurate point without shifting the tip of the drill from the point to be drilled.

The tip angle is preferably set in the range of 40 ° to 90 °.
Even if the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is further reduced by setting the tip angle in the range of 40 ° to 90 °, specifically, the contact angle is reduced to about 45 °. Even if it is shallow (small), it is possible to perform drilling to an accurate point without shifting the tip of the drill from the point to be drilled.

The tip angle is more preferably set in the range of 45 ° to 55 °.
Even if the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is very shallow by setting the tip angle in the range of 45 ° to 55 °, the contact angle is specifically about 30 °. Even if it is shallow (small), it is possible to perform drilling to an accurate point without shifting the tip of the drill from the point to be drilled.
In the solid medical drill according to the present invention, the optimum value of the tip angle can be 50 °, for example. In this case, as shown in FIG. 3, even if the contact angle is shallow (small) to 30 °, there is almost no possibility that the outer periphery of the drill hits the drilling target, and the drill tip is not displaced from the point to be drilled. It becomes possible to drill a point.
In addition, even when the tip angle is larger, it is possible to perforate with a contact angle shallower (smaller) to 30 °. Taking the case where the tip angle is 90 ° as an example, as shown in FIG. 4, after first forming a pilot hole with a contact angle of approximately 90 °, the contact angle may be gradually reduced. Such a drilling method is difficult when the tip angle exceeds 110 °.

In the solid medical drill according to the present invention, the twist angle is set in the range of 5 ° to 25 °.
When the twist angle is less than 5 °, the cutting resistance increases and the sharpness decreases. When the twist angle exceeds 25 °, the cutting edge easily bites like a wedge with respect to the drilling target, and the work piece (bone tissue) is broken. In either case, there is a fear that there is a risk.
By setting the twist angle in the range of 5 ° to 25 °, it is possible to smoothly perforate the workpiece (bone tissue) without causing cracks.

More preferably, the twist angle is set in a range of 15 ° to 20 °.
By setting the twist angle in the range of 15 ° to 20 °, it is possible to more reliably exhibit the function of smoothly drilling without causing cracks in the work piece (bone tissue).

Included angle formed by the main cutting edge (2) and (alpha _1), the cutting edge angle formed by the thinning cutting edge (1) (alpha ₂₎ is, α ₁ <α ₂ <satisfy 90 ° (Note, alpha ₍ Refer to FIG. 8 for ₁ and α ₂ ).

Here, a supplementary explanation of the rake angle and the edge angle will be given.
The rake angle inherent to the drill (rake angle before thinning formation) is too sharp and the cutting edge bites into the workpiece like a wedge, so that the cutting resistance increases.
By performing thinning, the rake angle is reduced and the edge angle is increased, thereby improving the sharpness (cutting resistance is reduced). In particular, according to the thinning applied to the solid medical drill according to the present embodiment, a gentle rake angle and a large cutting edge angle suitable for the treatment are created.

The clearance angle (β) is set so as to satisfy 5 ° <β ≦ 30 °.
In the solid medical drill according to the present invention, by setting the twist angle to be small, it is possible to smoothly drill without causing cracks in the drilled object (bone). By setting the clearance angle a little larger, it is possible to compensate for the reduction in cutting force caused by setting the twist angle smaller. In the solid medical drill according to the present invention, it is possible to cope with a workpiece (bone tissue) different from metal by setting the torsion angle to be small and setting the relief angle to be large.
In the solid medical drill according to the present invention, by setting the clearance angle (β) to 5 ° <β ≦ 30 °, the amount of biting into the workpiece (bone tissue) is adjusted, and the workpiece (bone tissue) ) Will be cut easily.

Here, the clearance angle (β) is defined by the following (A) or (B).
(B) The center of the drill tip is aligned with the horizontal center line of the grinding wheel outer periphery with a radius of 50 mm or more, the cutting edge of the drill tip is applied parallel (= horizontal) to the grinding wheel horizontal center line, and the rear end of the drill Is an angle formed by the grindstone horizontal center line and the drill center axis when the drill is lowered from the grindstone horizontal centerline with the drill tip as the center (see FIG. 5A).
(B) Align the center of the drill tip with the grindstone horizontal center line on the side of the grindstone (vertical plane), place the cutting edge of the drill tip parallel to the grindstone horizontal center line (= horizontal), and place the rear end of the drill The angle between the grinding wheel horizontal center line and the drill center axis when lowered from the grinding wheel horizontal center line around the drill tip (see FIG. 5B).

However, in (b) and (b), the angle (whetstone radius) generated by the grindstone radius shown in FIG. 5 (a) and the distance from the drill center to the cutting edge: 1/2 W (W: core thickness). When the thickness (W) is 50 mm at 50 mm, a difference of about 0.573 °, about 0.286 ° at a radius of 100 mm, and about 0.191 ° at a radius of 150 mm occurs.
Therefore, when calculating | requiring by (A), it is preferable to make into a clearance angle what added this difference. In other words, the clearance angle is preferably obtained as in the following formula.
(A) (FIG. 5A): clearance angle = β + tan ⁻¹ ((1−cos (sin ⁻¹ × 0.5 W / R)) R ÷ 0.5 W)
(B) (FIG. 5B): clearance angle = β
For example, the actual clearance angle of a drill having a diameter of 10 mm and a core thickness of 2 mm polished with a grinding wheel having a clearance angle of 3 ° and a radius (R) of 50 mm is about 3.573 °.

The chisel width (W) (see FIG. 1A) is preferably set to be small in order to easily cut the workpiece (bone tissue). Specifically, it is preferably set to 15% or less of the drill diameter. For example, when the drill diameter φ is 1 to 13 mm, the chisel width (W) is set to be increased or decreased within a range of 0.1 to 0.8 mm according to the increase or decrease of the drill diameter.
Although drill diameter (phi) is not specifically limited, For example, the thing about 1-6 mm is used suitably.

In the solid medical drill according to the present invention, the angle of thinning is set smaller than that of a conventional general drill.
In the conventional thinning, in order to give priority to the strength and rigidity of the drill itself, the angle (θ) at which the drill is applied to the grindstone during the thinning is increased (see FIG. 6A).
When the angle (θ) is reduced as much as possible and the center of the drill is brought closer to the grinding surface tangent of the grindstone, the resistance of the portion called the web at the center of the drill is not received, so the cutting resistance is greatly reduced (FIG. 6B). reference).

Next, the shape of the thinning will be described.
FIG. 8 is a view showing a cross section perpendicular to the thinning portion of the drill (a cross section having a line perpendicular to the line D in FIG. 1B as a cutting line).
In the example shown in FIG. 8, the edge of the rake face (6) formed by thinning (the boundary with the rake face (5) formed by the main cutting edge (2)) is the radius of thinning (R ₂ ). Are formed in an arc shape. Note that (R ₁ ) is the radius of the drill groove.
As shown, the main cutting edge (2) rake angle formed by the (theta _1), rake angle formed by the thinning cutting edge (1) (theta ₂₎ is, θ _1> θ _2> a 0 ° Fulfill.
Moreover, the main cutting edge angle formed by the (2) (α _1), the cutting edge angle formed by the thinning cutting edge (1) (α ₂₎ satisfy the _{α 1 <α 2 <90 °} .

  In the solid medical drill according to the present invention, the edge shape of the rake face is not limited to an arc shape, and may be a shape combining an arc and a straight line (see FIG. 9).

In the solid medical drill according to the present invention, when the ridgeline at the boundary between the thinning surface (8) and the chip discharge groove formed by the thinning cutting edge (1) is viewed from the drill front side, the drill axis direction It is formed in a substantially parabolic shape (substantially U-shape) inclined with respect to (C) (see FIG. 1B, FIG. 2, FIG. 10B, and FIG. 11B). In the present invention, the “front side of the drill” refers to the opening side of the chip discharge groove.
As shown in the figure, the direction of the inclination is the direction of transition from the thinning cutting edge (1) side to the main cutting edge (2) side as it goes from the drill tip side to the base end side (downward diagonally downward in front view). It is. The same applies to a solid medical drill according to the present invention described later.
The angle of inclination (γ) is set in the range of 10 ° to 25 ° (for example, 16.5 °). As described above, this angle setting is performed by setting the angle formed by the drill center axis with respect to the center line in the width direction of the grindstone to be thinned to be 10 ° to 25 ° (see FIG. 7). Can do. When thinning is performed, the angle at which the center of the grindstone (see the one-dot chain line (L) in FIG. 10A) is tilted with respect to the center axis in the longitudinal direction of the drill is determined by taking into account the twist angle of the drill. It is preferable to set in the range of ° to twist angle + 10 °. However, theoretically, this angle can be set from a twist angle of -10 ° to a half of the tip angle on the cutting edge side.
These configurations (the shape of the thinning cutting edge, the direction of inclination, and the angle of inclination) are common to the solid medical drills according to the first to fourth embodiments of the present invention.

The solid medical drill according to the first embodiment has a line extending along the deepest part (the deepest part scraped off by thinning) of the thinning surface (8) formed by the thinning cutting edge (1) in the drill tip direction. When viewed from the front side of the drill, the extension line (D) extended to is shifted to the heel side of the drill without crossing the drill tip center portion (7) (see FIG. 1B).
The deviation amount (d) is preferably within 10% of the drill diameter. This is because if it exceeds 10%, the cutting resistance increases and the sharpness decreases.

  A rake angle is formed at a portion of the thinning cutting edge (1) including the portion directly below the chisel (4). Since the rake angle is formed in the portion including directly under the chisel (4), a portion (9) in which the width in the direction parallel to the chisel is narrower than the chisel width (W) is formed immediately under the chisel (4). (See FIG. 12A).

[Embodiment 2]
FIGS. 10A and 10B are diagrams showing a solid medical drill according to the second embodiment of the present invention, in which FIG. 10A is a top view (view of the drill viewed from the distal end side), and FIG. 10B is a front view of the distal end portion. It is.
Also in the solid medical drill of the second embodiment, the thinning surface (8) formed by the thinning cutting edge (1) is inclined with respect to the drill axial direction (C) when viewed from the front side of the drill. It is formed in a substantially parabolic shape (substantially U-shape) (see FIG. 10B).
An extension line (D) extending along the deepest part (the deepest part scraped off by thinning) of the thinning surface (8) formed by the thinning cutting edge (1) extends in the direction of the drill tip is the front side of the drill When viewed from the side of the drill, it is shifted to the cutting edge side of the drill without intersecting with the center portion (7) of the drill tip.
The deviation amount (d) is preferably within 10% of the drill diameter. This is because if it exceeds 10%, the cutting resistance increases and the sharpness decreases.

  A rake angle is formed in a portion of the thinning cutting edge (1) in the vicinity immediately below the chisel (4) and not including the direct bottom. More specifically, a rake angle is formed on the main cutting edge (2) side from directly below the chisel (4) of the thinning cutting edge (1).

In the solid medical drill of the second embodiment, the cutting edge length in the extending direction of the main cutting edge (2) is the length of the main cutting edge (2) (A), and the thinning cutting edge (1) When the length is (B), A>B> 0 is satisfied.
And rake angle formed by the main cutting edge (2) (θ _1), rake angle formed by the thinning cutting edge (1) (θ ₂₎ satisfies the _{θ 1> θ 2> 0 °} . Only under the chisel (4), θ ₂ ≈0 ° (θ ₂ <0 ° close to 0 °).

[Embodiment 3]
11A and 11B are diagrams showing a solid medical drill according to the third embodiment of the present invention, in which FIG. 11A is a top view (a view of the drill viewed from the distal end side), and FIG. 11B is a front view of the distal end portion. It is.
In the solid medical drill of the third embodiment, the thinning surface (8) formed by the thinning cutting edge (1) is also inclined with respect to the drill axis direction (C) when viewed from the front side of the drill. It is formed in a substantially parabolic shape (substantially U-shape) (see FIG. 11B).
An extension line (D) extending in the drill tip direction from a line extending along the deepest part of the thinning surface (8) formed by the thinning cutting edge (1) is the center of the drill tip ( 7)

  A rake angle is formed in a portion of the thinning cutting edge (1) in the vicinity immediately below the chisel (4) and not including the direct bottom. More specifically, a rake angle is formed on the main cutting edge (2) side from directly below the chisel (4) of the thinning cutting edge (1).

In the solid medical drill of the third embodiment, the cutting edge length in the extending direction of the main cutting edge (2) is such that the length of the main cutting edge (2) is (A) and the thinning cutting edge (1) When the length is (B), A>B> 0.
And rake angle formed by the main cutting edge (2) (θ _1), rake angle formed by the thinning cutting edge (1) (θ ₂₎ is, θ _1> θ _2> 0 satisfy °. However, just below the chisel (4), θ ₂ ≈0 ° (θ ₂ <0 ° close to 0 °).

[Embodiment 4]
FIG. 13 is a view showing a solid medical drill according to a fourth embodiment of the present invention, in which (a) is a side view and (b) is a front view of a tip portion. 14A and 14B are diagrams showing a solid medical drill according to a fourth embodiment of the present invention, in which FIG. 14A is an enlarged side view of a chisel portion having a curved shape, and FIG. 14B is a straight shape (character shape). It is an enlarged side view of a chisel part provided with a shape.

The solid medical drill according to the present embodiment has features different from the first to third embodiments of the present invention. Specifically, a distal end portion (23) for cutting (piercing) a workpiece (bone tissue) and a proximal end portion (24) fixed to a rotation drive device (not shown) are provided. Two plane portions (25) are provided from the portion (23) toward the base end portion (24), and one or more thinning surfaces (26) are formed at the distal end portion (23). It has.
The solid medical drill according to the present embodiment does not have a twist, but may have a shape with a twist.

  In the solid medical drill according to the present embodiment, two flat portions (25) are provided on the tip side of the drill, the tip portion (23) is provided with a tip angle (ε), and the tip portion (23 ) Has a chisel portion (28) in the center portion (27), and one or more thinning surfaces (26) are substantially parallel to the cutting edge from the center portion (27) of the tip end portion (23) toward the outer peripheral portion (29). The flank (31) is formed on the opposite side of the rake face (30) of the cutting edge formed on the one or more thinning faces (26).

The flat surface portion (25) is formed from the distal end portion (23) toward the proximal end portion (24). From the viewpoint of cutting ability and durability, the plane portion (25) is desirably formed symmetrically with the rotational axis, but is not limited thereto, and may be formed asymmetrical with the rotational axis.
In FIG. 13 (a), the end on the base end (24) side of the plane portion (25) is curved, but is not limited to this, and may be, for example, a straight line or any shape. May be.

  Since the solid medical drill according to the present embodiment has two plane portions (25), the tip portion (23) is linear (a tip shape like a minus driver). Therefore, the tip angle (ε) is set like a normal drill, and the tip portion (23) is formed so that the tip portion (23) has a conical shape in the rotation state of the medical drill.

In the solid medical drill according to this embodiment, the tip angle (ε) is set in the range of 30 ° to 150 ° from the viewpoint of cutting ability and cutting resistance.
When the tip angle is less than 30 °, the tip of the drill becomes an irregular shape and the sharpness is lowered. When the tip angle exceeds 150 °, the drill is tilted so as to reduce the contact angle with the surface of the workpiece (bone tissue). Then, the tip of the drill slips and tends to be displaced from the drilling point, and there is a risk of damaging the human body (nerve etc.) during drilling, and the contact angle cannot be set shallowly below 75 °, and drilling into the bone is difficult Since the number of cases increases, either case is not preferable.
By setting the tip angle (epsilon) in the range of 30 ° to 150 DEG °, object to be cut be shallower contact angle of the drill to the surface of the (bone tissue), in particular contact angle 7 5 Even if it is shallow (small) to about 0 °, it is possible to perform drilling to a precise point without shifting the tip of the drill from the point to be drilled.

The tip angle (ε) is preferably set in the range of 40 ° to 90 °.
Even if the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is further reduced by setting the tip angle (ε) in the range of 40 ° to 90 °, specifically, the contact angle is set to 45. Even if it is shallow (small) to about 0 °, it is possible to perform drilling to a precise point without shifting the tip of the drill from the point to be drilled.

The tip angle (ε) is more preferably set in the range of 45 ° to 55 °.
By setting the tip angle (ε) in the range of 45 ° to 55 °, the contact angle can be set even if the contact angle of the drill with respect to the surface of the workpiece (bone tissue) is very shallow. Even if it is shallow (smaller) to about 30 °, it is possible to perform drilling to a precise point without shifting the tip of the drill from the point to be drilled.
In the solid medical drill according to the present embodiment, the optimum value of the tip angle (ε) can be 50 °, for example. In this case, as shown in FIG. 3, even if the contact angle is shallow (small) to 30 °, there is almost no possibility that the outer periphery of the drill hits the drilling target, and the drill tip is not displaced from the point to be drilled. It becomes possible to drill a point.
In addition, even when the tip angle (ε) is larger, it is possible to perforate with a contact angle shallower (smaller) to 30 °. Taking the case where the tip angle (ε) is 90 ° as an example, as shown in FIG. 4, first, after forming the pilot hole with the contact angle of approximately 90 °, the contact angle should be gradually decreased. Good. Such a drilling method is difficult when the tip angle (ε) exceeds 150 °.

The tip (23) of the solid medical drill according to the present embodiment is thinned, and one or more thinning surfaces (26) are formed.
The thinning surface (26) is formed substantially parallel to the cutting edge from the central portion (27) of the tip end portion (23) toward the outer peripheral portion (29), and is formed on one or more thinning surfaces (26). A flank (31) is formed on the opposite side of the rake face (30) of the blade (32). In this way, by forming the thinning surface (26) from the central portion (27) of the tip end portion (23) toward the outer peripheral portion (29) substantially parallel to the cutting edge, a rake face is provided on the entire cutting edge, thereby providing a clear cutting edge. A blade (32) can be created. The tip portion (23) has a chisel portion ( 28 ) in the center portion (27) like a drill, and is formed of a rake face (30) of a cutting edge (32) formed by providing a thinning surface (26). Since the flank (31) is formed on the opposite side, there is an advantage that the rotary cutting can be performed efficiently.
The chisel portion ( 28 ) may be a straight line, but if it has a shape including a curve (R) (see FIG. 14A), or a tip shape of a dogleg shape (L) (see FIG. 14B). Thus, the slip of the central portion (27) is suppressed, and an accurate treatment is performed in the bone perforation.

  The width of the chisel portion (chisel width) (W) (see FIG. 13B) is preferably set small so that the bone tissue can be easily cut. Specifically, it is preferably set to 10% to 20% of the drill diameter. For example, when the diameter φ is 0.5 to 6 mm, the chisel width (W) is desirably set to be increased or decreased in the range of 0.05 to 1.2 mm in accordance with the increase or decrease of the drill diameter.

Note that the shape of the thinning surface (26) is not limited to the above-described shape, and may be any shape as long as the cutting ability can be improved and the cutting resistance can be reduced.
Further, the length of the thinning surface (26) in the base end portion (24) direction (longitudinal direction) and the length in the width direction are not particularly limited, and may be a shape that can improve cutting ability and reduce cutting resistance. Any size is possible.

According to the solid medical drill according to the present embodiment, two plane portions are provided, a tip angle is provided at the tip portion, the tip portion has a chisel portion at the center portion, and one or more thinning surfaces are provided. The tip is formed substantially parallel to the cutting edge from the center to the outer periphery, and a flank is formed on the opposite side of the rake face of the cutting edge formed on one or more thinning surfaces. It is possible to provide a solid medical drill in which rotary cutting can be efficiently performed and the sharpness (cutting ability) of the center portion of the tip portion is greatly improved.
Moreover, since cutting resistance can be reduced significantly, heat generation during bone cutting can be suppressed, and necrosis of bone tissue during bone cutting can be suppressed.

[Embodiment 5]
A solid medical drill according to the fourth embodiment includes any of the features of the solid medical drill according to the first to fourth embodiments, and has a drill diameter of 1 mm to 4 mm, preferably 1 mm to 3 mm. It is a medical drill. By using the above-mentioned drill diameter, the pilot hole can be formed with a desired diameter at a desired location. In addition, since any of the features of the solid medical drill according to the first to fourth embodiments is provided, cutting resistance is lower than that of the conventional medical drill, and processing heat during bone drilling is suppressed. And a drill with high cutting ability can be provided.

In the solid medical drill according to the fifth embodiment, the length of the chip discharge groove (hereinafter referred to as the groove length (11)) is preferably shorter than the cutting depth (dep) of the bone to be cut (see FIG. 22). In the present specification, the groove length (11) refers to the length in the axial direction (longitudinal direction) where the chip discharge groove is provided.
In conventional drills (especially drills for cutting hard materials such as iron and stainless steel), the groove length of the chip discharge groove needs to be longer than the cutting depth of the workpiece (depth of the hole to be drilled). there were. By making the groove length (11) of the chip discharge groove longer than the cutting depth (dep), chips corresponding to the volume of the hole to be drilled are discharged out of the hole to be drilled through the chip discharge groove. However, if the groove length (11) of the chip discharge groove is increased, the strength of the drill is reduced. In addition, if the groove length (11) of the chip discharge groove is shorter than the cutting depth (dep), the chip cannot be discharged out of the hole, and the chip is clogged in the chip discharge groove and cutting is performed. As a result, there was a risk of breaking the drill.
The solid medical drill of this embodiment is intended for cutting bone tissue. Bone tissue has gaps between tissues as compared with iron, stainless steel, and the like, and a hole drilled at the time of cutting spreads in the width direction. Therefore, it is not necessary to discharge chips for the volume of the hole to be drilled out of the hole.
Since the solid medical drill of the present embodiment is used as a shaft (guide) of a hollow drill when cutting with a hollow drill after cutting bone tissue, the drill needs to have sufficient strength. is there. Therefore, if the groove length (11) of the chip discharge groove is the groove length of a conventional drill (groove length longer than the cutting depth of the workpiece), the strength of the drill is low, so when used as a shaft of a hollow drill There was a risk of damage such as the drill breaking.
Therefore, the solid medical drill of this embodiment has a cutting depth (dep) of the bone cut by the groove length (11) of the chip discharge groove so as to have sufficient strength and stability as the shaft of the hollow drill. Shorter than).

FIG. 22 is a diagram illustrating a state in which a bone (10) (for example, a femur) is cut using the solid medical drill of the present embodiment.
As shown in FIG. 22, in the solid medical drill of the present embodiment, the groove length (11) of the chip discharge groove is preferably shorter than the cutting depth (dep) of the bone to be cut. More specifically, the groove length (11) with respect to the cutting depth (dep) is preferably set to 8% to 30%, more preferably 10% to 20%.
With this ratio, when the solid medical drill of this embodiment is used as the shaft (guide) of a hollow medical drill, the drill is not easily damaged and the hollow medical drill is supported more stably. can do. However, the ratio of the groove length (11) to the cutting depth (dep) is not limited to the above ratio, and may be any ratio as long as the groove length (11) is shorter than the cutting depth (dep).

  Specific dimensions of each part of the solid medical drill according to the present invention are not particularly limited, but as a preferred example, drill diameter: 2.4 mm, groove core thickness: 20%, twist angle: 16 °, tip angle: 50 °, clearance angle (β): 25 °, and inclination angle (γ) of the thinning surface: 16.5 °.

The solid medical drills of the second to third embodiments are the same as the solid medical drill of the first embodiment when the thinning cutting edge (1) is viewed from the drill front side. In addition, it is characterized in that it is formed in a substantially parabolic shape (substantially U-shape) inclined with respect to the drill axis direction (C). Thereby, even if 0 <A ≦ B is not satisfied, the load applied to the chisel is reduced, and the chisel width can be narrowed. Specifically, the chisel width after thinning can be reduced to about 3 to 5% of the drill diameter. Therefore, the cutting resistance can be reduced and an excellent sharpness can be obtained, which has a great effect for drilling work (bone tissue), and an excellent sharpness for smoothly drilling bone etc. in a short time. A solid medical drill having
In addition, since the medical drills of the second to third embodiments have the tip angle and the twist angle set in the same manner as the medical drill of the first embodiment, the work piece (bone) Even if the drill contact angle to the surface of the tissue is shallow, it is possible to drill to an accurate point without shifting the tip of the drill from the point to be drilled, and to smoothly drill without causing cracks in the bone A solid medical drill that can be done.

Hereinafter, the shape of the grinding wheel for creating the thinning cutting edge (1) in the solid medical drill according to the first to third embodiments of the present invention will be described. 15-16 is a figure which shows the example of a grindstone shape, and has shown the rotating end part (outer peripheral part) of the grindstone.
The grindstone is a grindstone having one or more radii of curvature at the rotating end.
One of the curvature radius of the grindstone and R _1, to the R ₁ primarily radius for thinning cutting edge created across the cutting edge. Next adjacent to the R ₁ to the radius of curvature R ₂ that forms a curved surface smoothly connected to the R _1, mainly provided to strike the heel.

The _{R 1} and the two radii of curvature of the combination of _{R 2} to the basic, depending on the ratio of the diameter and web thickness of the drill, as shown in FIG. 15, the magnitude relation of _{R 1} and _{R 2 (R} 1 = _{R 2} , R ₁ <R ₂ , R ₁ > R ₂ ), a larger R ₃ between R ₁ and R ₂ to accommodate a thick drill, or a larger radius of curvature for the wheel width Therefore, small R ₄ and R ₅ are formed at the grindstone corner.
A grindstone that combines one or more radii of curvature may also be used.
Further, as shown in FIG. 16, thinning may be performed by including a straight portion between the R portions or by inclining the side surfaces.

[Embodiment 6]
The hollow medical drill according to the sixth embodiment includes a lumen (12) penetrating in the axial direction from the tip, and a plurality of cutting edges (15) are provided on the circumferential edge (14) of the tip (13). Have.
This hollow medical drill is mainly used for expanding a hole drilled by a solid medical drill having a drill diameter passing through the lumen (12).

  The shape of the cutting edge (15) (tip portion) of the hollow medical drill of the sixth embodiment is spherical when viewed from the direction perpendicular to the axial direction when the hollow medical drill rotates in the axial direction. Alternatively, an elliptical sphere is formed (see FIG. 17). More specifically, the shape of the tip portion side from the boundary line (17) between the tip portion (13) and the cylindrical portion (16) is spherical ((a) in FIG. 17), horizontally long (long in the width direction) elliptical sphere ( 17 (b)), a vertically long (long in the axial direction) ellipsoid (FIG. 17 (c)), or a corner R shape (FIG. 17 (d)).

Moreover, even if the cutting edge (15) of the hollow medical drill of the sixth embodiment includes the straight portion (20) from the inner diameter end (18) of the tip end portion (13) toward the outer peripheral portion (19). Good.
When the cutting edge (15) includes a straight line portion (20), the shape of the distal end portion (13) of the hollow medical drill according to the sixth embodiment is as shown in (a) to (d) of FIG. In addition, when the hollow medical drill rotates in the axial direction, a spherical shape or an elliptical shape including a straight line is formed when viewed from the direction perpendicular to the axial direction. More specifically, the shape of the tip portion side from the boundary line (17) between the tip portion (13) and the cylindrical portion (16) includes a sphere including a straight line ((a) in FIG. 18), a horizontally long shape including the straight line (in the width direction) (Long) elliptical sphere (FIG. 18 (b)), vertically long (long in the axial direction) ellipsoid (including the straight line) (FIG. 18 (c)), or corner R-shaped (including rounded corners) ((D) of FIG. 18).
The cutting blade (15) is provided with the straight portion (20) from the inner diameter end (18) to the outer peripheral portion (19) of the tip end portion (13), so that the cutting blade (15) is less likely to be worn and the cutting ability is reduced. Will improve.

As shown in FIG. 19A, the cutting edge (15) has a clearance angle (β ₂ ) on the back surface thereof. The clearance angle (β ₂ ) is set so as to satisfy 1 ° <β ₂ <20 °. Preferably, it is set to satisfy 3 ° <β ₂ <15 °, more preferably 5 ° <β ₂ <10 °.
Moreover, the front-end | tip part (13) is provided with the chip discharge groove | channel (21) hung from the internal diameter end (18) to the outer peripheral part (19). The chip discharge groove (21) is twisted with respect to the axial direction. The twist angle (twist angle (δ)) of the chip discharge groove (21) is set so as to satisfy 5 ° <δ <45 °. The angle is preferably set so as to satisfy 10 ° <δ <40 °, more preferably 15 ° <δ <30 °.
Since the chip discharge groove (21) is connected to the cylindrical part (16), chips are discharged from the outer peripheral part (19) during cutting.
Thus, the cutting edge (15) has a clearance angle (β ₂ ) on the back surface thereof, and a rake angle (θ ₃ ) is formed on the entire front surface of the cutting edge by twisting the chip discharge groove (21). can do.
The rake angle (θ ₃ ) on the front surface of the cutting edge is set so as to satisfy 2 ° <θ ₃ <20 °. Preferably, the angle is set to satisfy 5 ° <θ ₃ <15 °, more preferably 8 ° <θ ₃ <12 °.
In addition, a gash pocket (22) is provided on the inner diameter end (18) side of the cutting blade (15). By providing the gash pocket (22), it is possible to promote clear scooping and chip discharge.

A plurality of cutting blades (15) are preferably provided on the circumferential edge (14), more preferably 2 to 6 (see FIGS. 20 and 21). By providing a plurality of cutting edges (15), the cutting ability can be greatly improved. When seven or more sheets are provided, the cutting ability is improved, but the formation of the cutting edge becomes complicated, which is not preferable.
However, the number of cutting blades (15) may be one or seven or more depending on the cutting location and the desired cutting ability.
Further, in order to make the cutting force uniform, it is desirable that the plurality of cutting edges (15) be arranged on the circumferential edge (14) at equal intervals.

  The diameter of the lumen (12) of the hollow medical drill of the sixth embodiment is at least larger than the diameter of the solid medical drill of the first to fifth embodiments. The diameter of the lumen (12) of the hollow medical drill of the sixth embodiment is preferably 0.05 mm to 0.3 mm larger than the diameter of the solid medical drill of the first to fifth embodiments, More preferably, it is larger by 0.1 mm to 0.2 mm. As a result, it is possible to eliminate the complication of inserting the hollow drill and the shake of the hollow drill shaft, and smoothly perform bone drilling.

Although the first to sixth embodiments according to the present invention have been described above, it is desirable to use the two medical drills of the fifth and sixth embodiments as a set during bone drilling. However, the medical drills according to the first to sixth embodiments can be used alone or in combination.
Further, the material of the solid and hollow medical drills according to the first to sixth embodiments of the present invention is not particularly limited as long as it is a material allowed by the law of medical equipment, but stainless steel is preferably used. In particular, SUS420J, SUS440C and the like are preferably used.

  Below, an example of the bone drilling method for ligament reconstruction using the medical drill of 5th and 6th embodiment is described. It should be noted that bone drilling may be performed by combining the embodiments other than the above-described combinations or using them alone, and the drilling method may be any method commonly used for bone drilling.

Bone drilling consists of steps (1) to (3).
Step (1): Using the solid medical drill of the fifth embodiment, the bone medical cortex is placed at a predetermined position of the bone according to the diameter of the solid medical drill. A pilot hole is formed by drilling with the tip.
Step (2): The pilot hole is expanded with the hollow medical drill while the hollow medical drill of the sixth embodiment is inserted in the axial direction from the distal end of the lumen of the hollow medical drill.
Step (3): Only the solid medical drill is taken out from the enlarged hole, a tendon is passed through the enlarged hole, and both ends of the tendon are fixed to the bone.
In the bone drilling, the drills of the fifth and sixth embodiments are used, but the present invention is not limited to this.

By performing bone drilling according to the above method using the medical drill of the fifth and sixth embodiments, bone drilling can be performed more easily and more accurately than conventional bone drilling methods for ligament reconstruction. Can be reduced.
As a solid medical drill used with the medical drill of the sixth embodiment, the medical treatment described in “medical drill using Kirschner steel wire” filed separately by the applicant on the same day as the present application A drill can be used.

Cutting performance tests were conducted using the medical drills of the examples of the present invention and the comparative examples.
(Position displacement test during drilling in an inclined state)
The acrylic plate is tilted 45 ° and fixed to an NC milling machine (ON-3VII manufactured by Otori Kiko), the tip of a solid medical drill is rotated, and 9.57 mm is drilled in the vertical direction from the state swung on the acrylic plate. The amount of deviation in the axial direction and the Y-axis direction was measured by a laser type discrimination displacement sensor (Keyence (IL100) X direction, (IL300) Y direction) (see FIG. 23).
The following solid medical drills were used for the test.
Example: Solid medical drill according to the first embodiment Comparative example: Smith & Nephew guide pin Cutting with various solid medical drills was performed under the following conditions.
Number of revolutions: 13.33 s ⁻¹ (800 rpm)
Feeding speed: 5mm / min
In both the example and the comparative example, the protruding amount from the drill chuck to the drill tip was set to 110 mm.
The solid medical drills of Examples and Comparative Examples were those having a drill diameter of 2.4 mm.

(Test results)
Table 1 shows the deviations in the X-axis direction and the Y-axis direction that occurred during drilling with the solid medical drills of the examples and comparative examples.

As shown in Table 1, the displacement in the X-axis direction in the example was 0.344 mm, while the displacement in the X-axis direction in the comparative example was 0.970 mm.
Further, the deviation in the Y-axis direction in the example was 0.412 mm, while the deviation in the Y-axis direction in the comparative example was 1.162 mm.
As described above, it has been found that the solid medical drill according to the present invention has a very small deviation amount of the drill tip when drilling the inclined surface as compared with the conventional solid medical drill.
In actual operation, if the tip of a solid medical drill is placed at the drilling target location and the handpiece (hand drill for industrial use) is gradually rotated, the tip of the solid medical drill will be Since it is no longer a free end, a solid medical drill can drill a target location without slipping. At the same time, unlike a test with a machine tool, it is considered that the medical treatment drill is a solid medical drill capable of drilling at an extremely accurate position because it takes into account the control of the doctor who performs the operation.
Moreover, although the solid medical drill which concerns on 1st Embodiment was used in the said test, the solid medical drill which concerns on 1st Embodiment also in the solid medical drill which concerns on 2nd thru | or 4th embodiment. The test results similar to those for the drill were obtained.

Furthermore, a cutting performance test using the hollow medical drill according to the present invention and the conventional hollow medical drill was performed.
(Sharpness evaluation test for hollow medical drills)
For the cortex bone sheet (thickness: 10 mm) manufactured by Avis Co., Ltd., in the first embodiment where the tip is the same size and shape as that used in the above test (position displacement test during drilling in an inclined state). A real medical drill (2.4 mm in diameter x 255 mm in total length) is drilled vertically and the tip is kept in a state of about 1 mm, and then inserted into a cortical bone sheet. With the hollow medical drill inserted, the hollow medical drill was rotated using a striker handpiece, and the sharpness of the hollow medical drill was compared.

The length of the solid medical drill used as the guide pin is set so as to exceed the length of the hollow medical drill due to its nature.
When testing with a machine tool, etc., the chuck that grips the hollow medical drill hits the end of the solid medical drill and cannot be drilled. use. These handpieces have a structure in which the drill end can slide freely to the outside of the handpiece in accordance with the treatment method, so that the drilling is not impossible.

The following hollow medical drill was used for the test.
Comparative example: Smith & Nehue hollow drill (shape corresponding to (d) in FIG. 25), blade outer diameter: about 4.4 mm, hole diameter: about 2.6 mm, full length: about 203 mm, outer peripheral cutting edge Twist angle: 16 °
Example: Hollow medical drill according to the present invention in which the tip of a drill manufactured by Smith & Nehue Co. of Comparative Example is formed in a shape corresponding to FIG.

(Test results)
The sharpness of the comparative example and the example was confirmed by the evaluation by the three workers A to C that it was well cut (◯) and difficult to cut (Δ).
Table 2 shows the evaluation of sharpness by the hollow medical drills of Examples and Comparative Examples.

As shown in Table 2, all workers evaluated that the hollow medical drill of the example was better than the comparative example.
From this test result, it was found that the hollow medical drill according to the present invention has higher cutting ability than the conventional hollow medical drill.

  The medical drill according to the present invention is suitably used as a bone cutting drill, in particular, a bone drilling drill in reconstruction performed by anterior cruciate ligament tearing.

DESCRIPTION OF SYMBOLS 1 Thinning cutting edge 2 Main cutting edge 3 Relief surface 4 Chisel 5 Rake face formed by main cutting edge 6 Rake face formed by thinning 7 Drill tip center part 8 Thinning face formed by thinning cutting edge 11 Chip discharge groove Groove length 12 Lumen 13 Tip portion 14 Circumferential edge 15 Cutting edge 18 Inner diameter end 19 Outer portion 20 Straight line portion 21 Chip discharge groove 22 Gash pocket 23 Tip portion 24 Base end portion 25 Flat portion 26 Thinning surface 27 Center portion 28 Chisel portion 29 Outer peripheral portion 30 Rake face 31 Relief face 32 Cutting edge θ ₁ Rake angle formed by the main cutting edge θ ₂ Rake angle formed by the thinning cutting edge δ Torsion angle ε Tip angle α ₁ Formed by the main cutting edge Cutting edge angle α ₂ Cutting edge angle formed by thinning cutting edge β Clearance angle γ Inclination angle A Length of main cutting edge B Length of thinning cutting edge C Drill axis direction D Thin Extension line R at the deepest part of the ning surface Drill radius W Chisel width d Deviation

Claims (15)

A solid medical drill for bone cutting having two cutting edges formed symmetrically about the rotational axis and having a thinned tip.
When the cutting blade is viewed from the drill tip side, a thinning cutting blade extending in a shape including a curve from the chisel edge toward the drill outer peripheral side, and a main cutting blade extending from the end of the thinning cutting blade to the drill outer peripheral end Become
When the ridgeline at the boundary between the thinning surface and the chip discharge groove formed by the thinning cutting edge is viewed from the front side of the drill, which is the opening side of the chip discharge groove, the base from the drill tip side with respect to the drill axis direction. As it goes to the end side, it is formed in a substantially U-shape inclined in the direction of transition from the thinning cutting edge side to the main cutting edge side,
The rake angle θ ₁ formed by the main cutting edge and the rake angle θ ₂ formed by the thinning cutting edge satisfy θ ₁ > θ ₂ > 0 °,
The tip angle is 30 ° to 110 °, the twist angle is 5 ° to 25 °,
A solid medical drill, wherein the chip discharge groove has a groove length shorter than a cutting depth of a bone to be cut.   The solid medical drill according to claim 1, wherein the tip angle is 40 ° to 90 °.   The solid medical drill according to claim 2, wherein the tip angle is 45 ° to 55 °.   The solid medical drill according to any one of claims 1 to 3, wherein the twist angle is 15 ° to 20 °.   The solid medical drill according to any one of claims 1 to 4, wherein a drill diameter is 1 mm to 3 mm. It has a lumen that penetrates from the tip in the axial direction, has a plurality of cutting blades on the circumferential edge of the tip, and is drilled by a solid medical drill having a drill diameter that penetrates the lumen A hollow medical drill for cutting bone to expand a hole,
When the hollow medical drill is rotated in the axial direction, the shape of the tip portion is spherical or elliptical when viewed from the direction perpendicular to the axial direction,
The cutting blade has a clearance angle on the back surface,
A chip discharge groove is provided from the inner diameter end of the tip portion to the outer peripheral portion,
The chip discharge groove has a twist with respect to the axial direction, whereby a rake angle is formed on the front surface of the cutting blade,
A hollow medical drill for bone cutting, characterized in that a gash pocket is provided at the tip of the cutting edge.   The hollow medical drill according to claim 6, wherein the cutting blade includes a straight portion from an inner diameter end of the tip portion toward an outer peripheral portion.   The hollow medical drill according to claim 6 or 7, wherein the number of the plurality of cutting blades is 2 to 6.   The diameter of the said lumen | bore is 0.1 mm-0.2 mm larger than the diameter of the solid medical drill as described in any one of Claims 1 thru | or 5 characterized by the above-mentioned. The hollow medical drill according to claim 1. A tip for cutting the workpiece;
A solid medical drill for bone cutting that is thinned at the distal end with a proximal end fixed to the rotary drive device,
Two plane portions are provided from the distal end portion toward the proximal end portion,
A tip angle is provided at the tip,
One or more thinning surfaces are formed at the tip,
The tip has a chisel at the center,
The one or more thinning surfaces are formed substantially parallel to the cutting edge from the center of the tip toward the outer periphery;
A solid medical drill characterized in that a relief surface is formed on the opposite side of the rake face of the cutting blade formed on the one or more thinning surfaces.   The solid medical drill according to claim 10, wherein the tip angle is 40 ° to 90 °.   The solid medical drill according to claim 11, wherein the tip angle is 45 ° to 55 °.   The solid medical drill according to any one of claims 10 to 12, wherein a drill diameter is 1 mm to 3 mm.   A medical medical device comprising the solid medical drill according to any one of claims 1 to 5 and claims 10 to 13, and the hollow medical drill according to any one of claims 6 to 9. Drill set. (1) Using the solid medical drill according to any one of claims 1 to 5 and claims 10 to 13, the bone is determined at a predetermined position by the diameter of the solid medical drill. Piercing the bone cortex with the solid medical drill tip to drill a pilot hole;
(2) Using the hollow medical drill according to any one of claims 6 to 9, the solid medical drill is inserted in the axial direction from the distal end of the lumen of the hollow medical drill. While expanding the pilot hole with the hollow medical drill,
(3) A solid medical drill and a hollow comprising a step of removing only the solid medical drill from the enlarged hole, passing a tendon through the enlarged hole, and fixing both ends of the tendon to the bone. Bone drilling method for ligament reconstruction using a medical drill.