WO2006001551A1

WO2006001551A1 - Drill with disposable blade

Info

Publication number: WO2006001551A1
Application number: PCT/KR2004/001554
Authority: WO
Inventors: Sharon Moshe; Chang Hee Choi; Seok Ki Hwang
Original assignee: Taegutec Ltd.
Priority date: 2004-06-25
Filing date: 2004-06-25
Publication date: 2006-01-05

Abstract

Drill with a disposable blade including a blade (8) having a 'V' projection (8c) from a bottom side and a clamping groove started from a side of the V projection (8c) in a direction oblique to a drill axis, a drill body (7) having blade holders (7a) at opposite sides in a fore end part thereof and a 'V' slot (7e) in conformity with the 'V' projection (8c) on the blade (8) between the holders (7a), a locking pin (9) inserted through a pin inserting hole (7b) in the holder (7a) in the fore end part of the drill body (7) and positioned in the clamping groove, for clamping/unclamping the blade (8) to/from the drill body (7) by means of a cam action coming from angular rotation, and a stopper (10) provided in the drill body (7) at a circumference of the locking pin (9) for controlling an angle of rotation of the locking pin (9), thereby permitting easy fitting/removal and clamping of the blade (8) without removal of the locking component from the drill body (7) in replacement of the blade (8), to permit an easy handling of the drill with a disposable blade (8) and improve workability.

Description

DRILLWITH DISPOSABLE BLADE Technical Field The present invention relates to drills with a disposable blade used widely in drilling, and more particularly, to a drill with a disposable blade, in which the blade can, not only be firmly fastened to a drill body quickly, but also removed from the drill body, easily. Background Art In general, the drill with a disposable blade is provided with the drill body of steel and a blade of cemented carbide, which is fastened to the drill body with a screw, firmly. A related art drill with a disposable blade will be described with reference to FIGS. 1 and 2, briefly. FIG. 1 illustrates a perspective assembled view of one exemplary related art drill with a disposable blade. When it is intended to remove the disposable blade 2 from the drill body 1 , it is required to unscrew, and remove the screw 3 from the drill body 1, fully. In the meantime, FIG. 2 illustrates a disassembled perspective view of another exemplary related art drill with a disposable blade, wherein, in this case too, when it is intended to remove the disposable blade 5 from the drill body 4, it is required to unscrew, and remove the screw 6 from the drill body 4, fully. However, the related art drill with a disposable blade has the following problems. First, handling of the related art drill with disposable becomes the more difficult as a diameter of the drill becomes the smaller. Second, the many times of turn of the screw required for removal of the blade is cumbersome in view of handling. Third, the frequent loss of a small screw occurred in removal/fitting of the blade leaves the drill unable to use. Fourth, for the possible loss of the screw, a storage of extra screws has been required. At the end, above different problems causes a poor workability in making holes, and increases manpower and material managerial costs. Disclosure of Invention Accordingly, the present invention is directed to a drill with a disposable blade that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. An object of the present invention is to provide a drill with a disposable blade, in which blade fitting and removal and clamping are made easy and fast by means of a fast change method without removing locking components from a drill body in replacement of the blade for easy handling and improvement of workability of drilling. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the drill with a disposable blade includes a blade having a 'V projection from a bottom side and a clamping groove started from a side of the V projection in a direction oblique to a drill axis, a drill body having blade holders at opposite sides in a fore end part thereof and a 'V slot in conformity with the 'V projection on the blade between the holders, a locking pin inserted through a pin inserting hole in the holder in the fore end part of the drill body and positioned in the clamping groove, for clamping/unclamping the blade to/from the drill body by means of a cam action coming from angular rotation, and a stopper provided in the drill body at a circumference of the locking pin for controlling an angle of rotation of the locking pin. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Brief Description of Drawings The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention: In the drawings: FIG. 1 illustrates a perspective assembled view of one exemplary related art drill with a disposable blade; FIG 2 illustrates a disassembled perspective view of another exemplary related art drill with a disposable blade; FIG. 3 illustrates a perspective assembled view of a drill with a disposable blade in accordance with a preferred embodiment of the present invention; FIG 4 illustrates a back view of FIG 3; FIG 5 illustrates a disassembled perspective view of FIG. 3; FIG. 6 illustrates a perspective view of the locking pin in FIG. 5; FIG. 7 illustrates a left side view, a front view, and a right side view of the locking pin; FIG 8 illustrates a front view showing a state before the blade is inserted; FIG. 9 illustrates a front view showing a state after the blade is inserted; FIG. 10 illustrates a working state diagram showing relative positions of a clamping groove in a blade and an eccentric cam on a locking pin in a state insertion of the blade is completed; FIG. 11 illustrates a front view at a maximum fastening; FIG. 12 illustrates a working state diagram showing relative positions of a clamping groove in a blade and an eccentric cam part on a locking pin at the maximum fastening in FIG. 11 ; FIG. 13 illustrates a front view in a state the locking is maintained; FIG. 14 illustrates a working state diagram showing relative positions of a clamping groove in a blade and an eccentric cam on a locking pin in a state the locking is maintained as shown in FIG. 13; and FIG. 15 illustrates a graph showing a position of the locking pin vs. a locking torque when a blade is fitted to a drill with a disposable blade of the present invention. Best Mode for Carrying Out the Invention Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. FIG. 3 illustrates a perspective assembled view of a drill with a disposable blade in accordance with a preferred embodiment of the present invention, FIG. 4 illustrates a back view of FIG. 3, and FIG. 5 illustrates a disassembled perspective view of FIG 3. Referring to FIGS. 3, 4, and 5, the drill with a disposable blade includes a blade 8 having a 'V projection 8c from a bottom side and a clamping groove started from a side of the V projection 8c in a direction oblique to a drill axis, a drill body 7 having blade holders 7a at opposite sides in a fore end part thereof and a 'V slot 7e in conformity with the 'V projection 8c on the blade 8 between the holders 7a, a locking pin 9 inserted through a pin inserting hole 7b in the holder 7a in the fore end part of the drill body 7 and positioned in the clamping groove, for clamping/unclamping the blade 8 to/from the drill body 7 by means of a cam action coming from angular rotation, and a stopper 10 provided in the drill body 7 at a circumference of the locking pin 9 for controlling an angle of rotation of the locking pin 9. The clamping groove in the blade 8 includes a straight guide groove part 8a formed along an oblique line to the drill axis, and a recess 8b of a circular, oval, or polygonal form, or a combination thereof at an end of the guide groove part 8a positioned away from the drill axis. FIG. 6 illustrates a perspective view of the locking pin in FIG 5, and FIG. 7 illustrates a left side view, a front view, and a right side view of the locking pin. Referring to FIGS. 6 and 7, the locking pin 9 includes a cylindrical body part 9b to be inserted through the pin inserting hole 7b in the drill body 7, an eccentric cam part 9a at one end of the body part 9b with an axis away from an axis of the body part 9b for positioning in the recess 8b of the clamping groove in the blade 8 when assembled, for applying a pressure to an inside surface of the recess 8b in the clamping groove and pushing the blade 8 toward the drill body 7 according to a position of rotation, and a head part 9c having a cam recess 9c- 1 recessed inwardly from and along a part of a circumference thereof at the other end of the body part 9b for controlling a range of rotation of the locking pin 9 by means of interference with the stopper 10. The head part 9c of the locking pin 9c has a diameter D2 greater than a diameter Dl of the body 9b on the whole. This is for prevention of further insertion of the locking pin 9 by catching the head part 9c at a ledge 7c inside of the pin inserting hole 7b when the cylindrical body part 9b is inserted to the pin inserting hole 7b. The eccentric cam part 9a of the locking pin 9 has a major diameter greater than a width 'W of the guide groove part 8a of the clamping groove, and a minor diameter smaller than the width 'W of the guide groove part 8a of the clamping groove. The head part 9c has a wrench hole 9c-2 at a top for inserting a wrench 11 therein when it is intended to rotate the locking pin 9. The cam recess 9c- 1 in the locking pin head part 9c is formed in a range of angle 'α' of 60° ~ 320°, and preferably 90° ~ 270°. The cam recess 9c- 1 has a cam recess surface 9c-l-l concentric with the body part 9b for making interference with the stopper 10 to stop or rotate the locking pin 9. The cam recess surface 9c- 1-1 has a contact cam recess surface 9c-l-la concentric with the body part 9b for making contact with an outside circumference of the stopper 10, and stopping cam recess surfaces 9c-l-lb each having a curvature opposite to the contact cam recess surface extended from both ends of the contact cam recess surface 9c-l-la concentric with the body part 9b. Moreover, the eccentric cam part 9a has a sloped surface 9a- 1 in a region thereof formed to be the closer to the axis of the locking pin 9 as it goes closer to the end thereof along the axis, for easy engagement/disengagement of the locking pin 9 with the blade 8. In the meantime, the stopper 10 is provided such that a part of the head 10a is positioned in a region of the locking pin insertion hole 7b. That is, when the stopper 10 is screwed into a stopper fastening hole 7d in a state the locking pin 9 is inserted in the locking pin insertion hole 7b, the head 10a of the stopper is positioned at the cam recess 9c- 1 in the locking pin 9, for preventing the locking pin 9 from falling off the locking pin insertion hole 7b. The stopper 10 and the locking pin 9 are formed not to be projected from an outside surface of the drill body 7. In the meantime, the 'V projection 8c of the blade 8 has a sloped surface at one side for easy insertion into an inside of the holders 7a on opposite sides of the fore end part of the drill body 7 in assembly. A process for fitting/removal of the blade to/from the drill with a disposable blade of the present invention will be described. It is needless to say that a process for inserting the locking pin 9 into the pin insertion hole 7b of the drill body 7, and fitting the stopper 10 to the drill body 7 is required before fitting the blade 8 to the drill body 7. The following description will be given on the assumption that the drill with a disposable blade is in a state the locking pin 9 and the stopper 10 are fitted to the drill body 7, already. FIG. 8 illustrates a front view showing a state before the blade is inserted, and FIG. 9 illustrates a front view showing a state after the blade is inserted. Referring to FIGS. 8 and 9, after inserting the wrench 11 in the wrench hole 9c-2 in the head part 9c of the locking pin, the wrench 11 is rotated in an anti-clockwise direction when the drawing is looked down until the rotation ends, to stop the wrench at a position rotated by 'A⁰' in the anti-clockwise direction with reference to a vertical line as shown in FIG. 8. Since a direction of the major axis of the eccentric cam part 9a of the locking pin 9 is the same with a length direction of the guide groove part 8a of the clamping groove in this state, enabling insertion of the blade 8 into the drill body 7, the blade 8 is moved in a direction of an arrow in the drawing (i.e., in a direction the guide groove part 8a is formed) in a state the clamping groove part in the blade 8 is positioned opposite to the locking pin 9 fitted to the drill body 7, to insert the blade 8 into the drill body 7. When the blade 8 is moved in the direction of the arrow in FIG. 8 and inserted into the drill body 7, a state as shown in FIG. 9 is brought about. In the meantime, referring to FIG. 9, in a state the blade 8 is inserted in the drill body 7 simply, if a positional relation of the clamping groove in the blade 8 and the eccentric cam part 9a in the locking pin 9 is examined on a working state drawing as shown in FIG 10, it can be known that the eccentric cam part 9a of the locking pin 9 is positioned at a center part of the recess 8b of the clamping groove, substantially. Under this state, for fastening the blade 8 to the body 7 firmly, the wrench 11 in the wrench hole 9c-2 in the head part 9c of the locking pin is rotated in a clockwise direction, to rotate the locking pin 9, when a rotation torque on the locking pin 9 becomes the maximum at a position the locking pin is rotated by 'B⁰' in the clockwise direction with reference to the vertical line as shown in FIG. 11. That is, FIG. 12 illustrates a section of key parts of FIG. 11 of a working state diagram showing relative positions of a clamping groove in a blade 8 and an eccentric cam part 9a on a locking pin 9 in a state the wrench 11 is at the maximum fastening position, wherein it can be known that the rotation torque applied to the locking pin 9 is the greatest as a contact area between the eccentric cam part 9a of the locking pin 9 and the inside surface of the recess 8b of the clamping groove is the greatest. In the meantime, as can be known from FIG 12, in this case, since the eccentric cam part 9a on the locking pin 9 is eccentric from the drill axis by a distance, and a center of the contact area between the eccentric cam part 9a of the locking pin 9 and the recess 8b is positioned high, the clamping force to the blade 8 mostly acts as a force pushing the blade 8 in a lateral direction. That is, in this case, a surface pressure acting between the 'V projection 8c on the blade 8 and the slot 7e in the drill body 7 is greater than a force pushing the blade 8 down, vertically. In the meantime, FIG. 13 illustrates a front view of the drill with a disposable blade in a state the locking is maintained, and FIG. 14 illustrates a front view of a section of key parts of FIG 13 for describing an operation of the present invention. Referring to FIGS. 13 and 14, in continuation from the state of FIGS. 11 and 12 described before, when a stronger torque is applied to the wrench 11 in the clockwise direction, a locking force drops a little as the contact area between the eccentric cam part 9a of the locking pin 9 and the recess 8b in the clamping groove starts to reduce, and at a position the wrench 11 is rotated by 'C°' with reference to the vertical line, the stopping cam recess surface 9c-l-lb of the cam recess 9c-l in the head part 9c of the locking pin is caught at the head 10a of the stopper at a side of the locking pin 9, allowing no more rotation of the locking pin 9. According to this, the blade 8 is fitted to the drill body 7 firmly, and, in this state locking of the blade 8 is maintained, the 'V projection 8c and other lower surface of the blade 8 firmly maintain a closely fitted state with the 'V slot 7e and other fore end surface of the drill body 7. Meanwhile, in this instance, as can be known from FIG 14, since the center of contact area between the eccentric cam part 9a of the locking pin 9 and the recess 8b is high, a clamping force acting on the blade 8 mostly acts as a force pushing the blade 8 down, vertically. That is, in this instance, the surface pressure between a horizontal bottom surface of the blade 8 and a horizontal fore end surface of the drill body 7 becomes relatively greater than the surface pressure acting between the 'V projection 8c of the blade 8 and the 'V slot 7e in the drill body 7. As described, for replacing the blade 8 again in a state the blade 8 is fitted to the drill body 7, as a reverse process of the fitting process, after removing the blade 8 from the drill body 7 in a state the locking pin 9 is rotated to 'A⁰' position in the anti- clockwise direction with reference to the vertical line, a new blade may be fitted to the drill body 7 readily through the foregoing fitting process, again. In the meantime, FIG 15 illustrates a graph showing a position of the locking pin vs. a locking torque when a blade is fitted to a drill with a disposable blade of the present invention. Referring to FIG 15, it can be noted that no torque acts in a simple assembly state of the blade 8 to the drill body 7 by rotating the wrench 11 by 'A°' in the anti-clockwise direction with reference to the vertical line, and, when the wrench 11 is rotated in the clockwise direction beyond the vertical line, the torque to the locking pin 9 increases gradually starting from the moment the eccentric cam part 9a of the locking pin 9 starts to contact with the inside surface of the recess 8b. It can be further noted that the greatest torque acts on the locking pin 9 at a position the wrench 11 is rotated by 'B°' in the clockwise direction with reference to the vertical line, and, thereafter, the torque is reduced gradually such that the locking state is maintained by the stopper 10 in a state the wrench 11 is rotated by 'C⁰' in a clockwise direction with reference to the vertical line, where the locking of the locking pin 9 can not be loosened in any worst drilling condition, because the locking pin 9 is out of a peak torque. That is, in the drilling, even though a rotation torque onto the locking pin 9 coming from a resistance of a working object following rotation direction of the drill acts to rotate the locking pin 9 in the clockwise direction when the drawing is looked down, the clockwise direction rotation of the locking pin 9 is impossible due to the stopper 10. Moreover, in the drilling, even though a vibration onto the drill acts as a torque for rotating the locking pin 9 in the anti-clockwise direction, which needs to be greater than the torque acting to the locking pin 9 at the maximum fastening position for loosening the locking pin 9 in the anti-clockwise direction, since there is no torque greater than this onto the locking pin 9 in the drilling, the locking pin 9 is not loosened in the anti-clockwise direction. Accordingly, different from the related art drill with a disposable blade in which components, such as the locking screw, is removed completely in removal of the blade from a small sized drill with a disposable blade by using small components, since the drill with a disposable blade of the present invention can remove the blade 8 in a state the components, such as the locking pin 9, is not removed, the loss of the components can be prevented. Along with this, different from the related art drill with a disposable blade in which the blade is removed by turning the locking screw many times, and a new blade is fitted by turning the locking screw many times again, since the drill with a disposable blade of the present invention can replace the blade 8 by rotating the locking pin 9 within a 360° range, not only the inconvenience of replacement of the blade 8 can be solved, but also a time period required for the replacement can be shortened. Industrial Applicability As has been described, the present invention provides a drill with a disposable blade, which, not only requires no removal of a locking component from the drill body in replacement of the blade, but also permits easy fitting/removal and clamping of the blade by rotating the locking pin within a 360° range. According to this, the present invention prevents loss of components as the blade replacement can be carried out without removal of the locking component, and resolves the inconvenience of working caused by many times of turning of the locking screw like the related art. Moreover, the reduction of a blade replacement time period coming from the easy replacement of the blade improves workability of drilling. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

What is Claimed is: 1. A drill with a disposable blade comprising: a blade having a 'V projection from a bottom side and a clamping groove started from a side of the V projection in a direction oblique to a drill axis; a drill body having blade holders at opposite sides in a fore end part thereof and a 'V slot in conformity with the 'V projection on the blade between the holders; a locking pin inserted through a pin inserting hole in the holder in the fore end part of the drill body and positioned in the clamping groove, for clamping/unclamping the blade to/from the drill body by means of a cam action coming from angular rotation; and a stopper provided in the drill body at a circumference of the locking pin for controlling an angle of rotation of the locking pin.

2. The drill as claimed in claim 1, wherein the clamping groove in the blade includes; a straight guide groove part formed along an oblique line to the drill axis, and a recess of a circular, oval, or polygonal form, or a combination thereof at an end of the guide groove part, the recess being positioned away from the drill axis.

3. The drill as claimed in claim 1, wherein the locking pin includes; a cylindrical body part inserted through the pin inserting hole in the drill body, an eccentric cam part at one end of the body part with an axis away from an axis of the body part for positioning in the recess of the clamping groove in the blade when assembled, for applying a pressure to an inside surface of the recess in the clamping groove and pushing the blade toward the drill body according to a position of rotation, and a head part having a cam recess recessed inwardly from and along a part of a circumference thereof at the other end of the body part for controlling a range of rotation of the locking pin by means of interference with the stopper.

4. The drill as claimed in claim 3, wherein the head part of the locking pin has a diameter greater than a diameter of the cylindrical body part.

5. The drill as claimed in claim 3, wherein the eccentric cam part of the locking pin has a major diameter greater than a width 'W of the guide groove part of the clamping groove, and a minor diameter smaller than the width 'W of the guide groove part of the clamping groove.

6. The drill as claimed in claim 3, wherein the head part includes a wrench hole in a top thereof for inserting a wrench therein when it is intended to rotate the locking pin.

7. The drill as claimed in claim 3, wherein the cam recess in the locking pin includes a cam recess surface for stopping or rotating the locking pin by means of interference with the stopper, wherein the cam recess surface includes; a contact cam recess surface concentric with the body part for making contact with an outside circumference of the stopper, and stopping cam recess surfaces each having a curvature opposite to the contact cam recess surface extended from both ends of the contact cam recess surface concentric with the body part.

8. The drill as claimed in claim 3, wherein the cam recess is formed in a range of angle 'α' of 60° ~ 320°

9. The drill as claimed in claim 3, wherein the eccentric cam part includes a sloped surface in a region thereof formed to be the closer to the axis of the locking pin as it goes closer to the end thereof along the axis.

10. The drill as claimed in claim 1, wherein the head of the stopper is fitted such that a part of the head is positioned in a region of the locking pin inserting hole.

11. The drill as claimed in claim 1 or 10, wherein the stopper and the locking pin are fitted not to be projected from an outside surface of the drill body.

12. The drill as claimed in claim 1, wherein the 'V projection on the blade includes one sloped side for easy insertion into an inside of holders at opposite sides of a fore end part of the drill body when the blade is assembled with the drill body.