JP2013059988A - Core bit set for power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a core bit set for a power tool, in which a core bit and a shank part are stably fixed to each other without causing backlash and in which the core bit is attached to/detached from the shank part through good operability.SOLUTION: The core bit set for the power tool includes: a mounting shaft 21 to be mounted onto a power tool body; a fixed flange 22 fixed to the mounting shaft 21; and a push ring 26 and a movable flange 24 which are movable in an axial direction with respect to the mounting shaft 21 and the fixed flange 22, and further includes projections 23, 25 which are provided at outer circumferential surfaces of the fixed flange 22 and the movable flange 24, respectively. Engagement of the projections with a notch part 13 fixes the core bit 10 to the shank part 20. In the notch part 13, an axial-direction notch 13a extending in an axial direction, a first circumferential-direction notch 13b extending in a circumferential direction from the intermediate point of the axial-direction notch 13a, and a second circumferential direction notch 13c extending in the circumferential direction from a lower end of the axial-direction notch 13a are formed. Further a lock part 13g for limiting movement of the movable flange projection 25 is provided at a terminal of the second circumferential-direction notch 13c.

Description

  The present invention relates to a core bit group that can be attached to the tip of a power tool, and more particularly to a one-touch attachment structure to a shank portion of a core bit that can be drilled in a cylindrical shape.

  Currently, large diameter drilling of concrete or stone is often performed by attaching a core bit (diamond core bit) having a diamond core to the tip of a power tool such as a hammer drill. The diamond core bit has a plurality of diamond blade portions arranged in a segment shape (divided and arranged) at the edge of the tip of the cylindrical body. After drilling with such a diamond core bit, the cut material (core) remains inside the core bit, so when performing the next drilling operation, the core remaining inside the core bit must be taken out. Don't be. However, in drilling concrete or stone, it is often impossible to smoothly remove the remaining core from the tip opening (diamond blade) side, so remove the core bit from the shank and remove the core. The core bit that can be realized. In this structure, the core bit is attached to the power tool through the shank portion. In the case of such a core bit set, in order to take out the core, the core bit is separated from the shank portion, and the rear end side of the core bit ( The core can be removed by extruding the residual core from a hole on the shank portion side) with something like a stick.

  However, since the conventional core bit and the shank portion are fixed by screws, the core bit and the shank portion are tightly tightened during the drilling operation, and it may take considerable labor and time to separate the core bit and the shank portion after the drilling operation. In order to eliminate this drawback, in recent years, an attachment structure that can separate the core bit and the shank portion with one touch has been proposed. For example, a technique described in Patent Document 1 is known.

Japanese Patent Laid-Open No. 9-1413

  In Patent Document 1, since the shank portion and the fastening pin are not integral, the fastening pin moves downward in the axial direction in the case of a drilling operation in which the tool body is lifted upward, and between the flange portion of the shank portion and the core body. There is a risk of rattling, and noise and vibration may be deteriorated.

  The present invention has been made in view of the above background, and an object of the present invention is to provide a core bit set for a power tool which can be fixed without causing play between the core bit and the shank portion.

  Another object of the present invention is to provide a core bit set for a power tool that can be stably fixed to a shank portion without being unlocked unless it is manually operated.

  Still another object of the present invention is to provide a power tool core bit set with good operability when the core bit is attached and detached.

  The characteristics of representative ones of the inventions disclosed in the present application will be described as follows.

  According to one aspect of the present invention, there is provided a core bit set including a shank portion attached to a power tool and a cylindrical core bit detachably fixed to the shank portion, and the shank portion is attached to the power tool. Mounting shaft, a fixed member fixed to the mounting shaft and having a protrusion, a movable member having a protrusion provided to be movable in the axial direction with respect to the fixed member, and the movable member in the axial direction with respect to the fixed member And a spring for biasing. On the other hand, the core bit has a blade provided at the lower end of the cylindrical body, a first engaging means that engages with the protrusion of the movable member, and a second that engages with the protrusion of the fixed member in the axial direction. It has an engagement means. The first engaging means and the second engaging means are notches or grooves formed in the body, and the circumferential positions of the entrance portions of the notches or grooves in which the protrusions of the fixed member and the movable member are guided Are formed to be the same.

  According to another feature of the invention, the notch or groove comprises an axial portion extending in the axial direction from the open end of the body, a first circumferential portion extending in the circumferential direction from the middle of the axial portion, and the axial direction. It is formed from a second circumferential portion extending in the circumferential direction from the lower end of the portion, and the movement in the circumferential direction is restricted by moving the protrusion of the movable member at a small distance in the axial direction at the end of the second circumferential portion. A lock was provided. It is preferable that the fixing member is provided with a collar portion that contacts the upper edge portion of the core bit body. Furthermore, a push ring is provided above the fixed member to move the movable member, and the push ring is fixed to the movable member located below the fixed member by a plurality of pins that pass through holes formed in the fixed member. The spring is interposed between the push ring and the fixing member. The protrusion of the fixed member and the protrusion of the movable member are disposed at the same angular position and rotate together in the axial direction.

  According to still another aspect of the present invention, the body is connected to the shank portion by engaging the cylindrical body, the blade provided at one end of the body, the fixed member of the shank portion, and the protruding portion of the movable member. In the core bit having the protrusion locking means fixed to the protrusion, the protrusion locking means is a notch or groove formed in the body, the notch or groove extending in the axial direction from the opening end of the body, and A first circumferential portion extending in the circumferential direction from the middle of the axial portion, and a second circumferential portion extending in the circumferential direction from the lower end of the axial portion, and is movable at the end of the second circumferential portion. A lock portion is provided that restricts movement in the circumferential direction by moving the protrusion of the member by a small distance in the axial direction. The axial portion has a first circumferential width on the inlet side, a second circumferential width narrower than the first circumferential width on the back side, and the first to second circumferential width portions. The connecting portion is formed with an oblique cutout or groove so as to generate a component force that moves the core bit away from the shank portion when the body is rotated by the protrusion of the movable member coming into contact therewith.

  According to the first aspect of the present invention, the core bit is fixed to the shank portion by engaging the protrusion provided on the fixed member and the movable member and the protrusion locking means provided on the body of the core bit. The core bit can be fixed stably by the portion.

  According to the invention of claim 2, since the first engaging means and the second engaging means are notches or grooves formed in the body, the body can be easily processed and the manufacturing cost can be reduced. . In addition, since the entrance of the engaging groove with the fixed member protrusion and the engaging groove with the protrusion of the movable member is the same location, more circumferential notches and grooves can be formed in the core bit body. Become. Furthermore, compared with the case where the grooves are individually machined, it is possible to save the labor of machining, so that the manufacturing cost can be reduced.

  According to invention of Claim 3, a notch or a groove | channel is an axial direction part, the 1st circumferential direction part extended in the circumferential direction from the middle of an axial direction part, and the 2nd extended in the circumferential direction from the lower end of an axial direction part. Therefore, it is possible to realize the protrusion locking means having the entrance of the engaging groove at the same location. Moreover, since the lock part was provided in the terminal of the 2nd circumferential direction part, it can prevent that a core bit remove | deviates from a shank part while using a power tool.

  According to the invention of claim 4, since the fixing member is formed with the flange portion that contacts the upper edge of the body of the core bit, even when a force that lifts the power tool upward is applied during the drilling operation, There is no play between the collar and the upper end of the core bit body.

  According to the fifth aspect of the present invention, the push ring that is located above the fixed member and moves the movable member is provided, and the push ring is provided on the lower side of the fixed member by the plurality of pins that pass through the holes formed in the fixed member. Since the spring is interposed between the push ring and the fixed member, the movable member can be easily moved relative to the axial direction simply by moving the push ring located at the top. As a result, since the protrusion provided on the outer peripheral side of the movable member can be moved in the axial direction, the protrusion can be reliably engaged with the lock portion. In addition, since the movable member and the push ring are fixed by a pin penetrating the fixed member, a simple structure can be achieved and the manufacturing cost can be reduced.

  According to the sixth aspect of the present invention, the fixed member protrusion and the movable member protrusion are arranged at the same angle and rotate together, so that the attachment / detachment operation can be performed with one action.

  According to invention of Claim 7, the axial direction part extended in the axial direction from the opening end of a body, the 1st circumferential direction part extended in the circumferential direction from the middle of an axial direction part, and the circumferential direction from the lower end of an axial direction part Since the second circumferential direction portion is extended, and the lock portion is provided at the end of the second circumferential portion to limit the circumferential movement by moving the protrusion of the movable member by a small distance in the axial direction. A core bit that can be stably fixed to the shank portion can be realized.

  According to the invention of claim 8, since the notch or the groove is formed obliquely in the axial direction portion of the protrusion locking means, the direction in which the core bit is separated from the shank portion when the body is rotated by the contact of the protrusion of the movable member It is possible to easily release the close contact state between the core bit and the shank portion simply by rotating.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

It is a front view showing the whole core bit set 1 concerning the example of the present invention. It is a fragmentary perspective view which shows the attachment structure to the shank part 20 of the core bit 10 which concerns on the Example of this invention. It is a perspective view which shows the components structure of the movable part of the shank part 20 of FIG. It is a perspective view which shows the state which assembled the component of the movable part of the shank part 20 of FIG. It is a front view which shows the free state of the shank part 20 of FIG. It is a front view which shows the state at the time of engagement of the shank part 20 of FIG. It is a side view which shows the shape of the notch formed in the core bit 10 which concerns on a 2nd Example (at the time of mounting | wearing). It is a side view which shows the shape of the notch part formed in the core bit 10 which concerns on a 2nd Example (at the time of removal).

  Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same portions are denoted by the same reference numerals, and repeated description is omitted. Further, in the present specification, description will be made assuming that the vertical direction is the direction shown in each drawing. FIG. 1 is a front view showing the entire core bit set 1 according to this embodiment.

  The core bit set 1 includes a shank portion 20 that is attached to a power tool such as a vibration drill or a hammer drill, and a core bit 10 that is detachably fixed to the shank portion 20. The shank portion 20 is provided with a fixed flange protrusion 23 and a movable flange protrusion 25 which are protrusions protruding outward. The core bit 10 is mainly configured by a cylindrical body 11 and a blade portion 12 at the lower edge of the body 11. A protrusion locking means for holding the core bit 10 on the shank portion 20 by locking the fixed flange protrusion 23 and the movable flange protrusion 25 is provided at the upper edge of the body 11. In the present embodiment, the protrusion locking means is realized by the notch portion 13, and the notch portion 13 is provided at four positions separated by 90 degrees in the circumferential direction. The fixed flange protrusion 23 and the movable flange protrusion 25 protruding from the shank portion 20 engage with predetermined end portions of the notch portion 13.

  A mounting shaft 21 is provided on the shank portion 20. The mounting shaft 21 has a circular shape with three chamfered planes in a cross section perpendicular to the axial direction, and is attached to the output shaft of a power tool such as a vibration drill or a hammer drill. The fixed flange protrusion 23 is fixed to a fixed flange 22 (fixed member) that is not movable with respect to the mounting shaft 21. On the other hand, the movable flange projection 25 is fixed to a movable flange 24 (movable member) that can be moved relative to the mounting shaft 21 only in the axial direction (vertical direction), and thus can move in the axial direction within a predetermined range. . Near the center of the shank portion 20 in the vertical direction, a push ring 26 that can move relative to the mounting shaft 21 in the axial direction is provided. The push ring 26 is a member for moving the movable flange 24 in the axial direction to change the position of the movable flange protrusion 25 when removing the core bit 10 from the shank portion 20. The push ring 26 is fixed by the movable flange 24 and a plurality of fixing pins 27. A compression spring 28 is provided between the push ring 26 and the fixed flange 22. The push ring 26 is urged upward by the compression spring 28 with respect to the fixed flange 22.

  The body 11 of the core bit 10 of the present embodiment has a diameter d of 65 mm, and the body 11 has a height (axial length) H of 150 mm. The diameter d1 of the mounting shaft 21 is 13 mm. However, although the shank portion 20 is used in common, the size of the core bit 10 is arbitrary, and the size of the body 11 may be, for example, about 20 mm to 150 mm, and in some cases, may exceed 150 mm. The shank portion 20 may be prepared in a different size for each core bit 10 having a different diameter, but it is preferable that the shank portion 20 be as common as possible. At this time, in order to attach the core bit 10 having a size different from the diameters of the fixed flange 22 and the movable flange 24, the large diameter portion and the small diameter portion are stepped so that the diameters of the blade portion 12 side and the upper end side of the body 11 are different. It may be configured to be formed in a shape or connected so that the diameter smoothly changes to be thicker or thinner.

  FIG. 2 is a partial perspective view showing a structure for attaching the core bit 10 to the shank portion 20 according to the embodiment of the present invention. Each part of the shank part 20 is attached to a power tool and rotates together in the rotation direction. However, in the axial direction (the same as the vertical direction in the definition of this embodiment), a portion that does not move with respect to the mounting shaft 21 (fixed portion) and a portion that can move relative to the mounting shaft 21 ( It is divided into two (movable parts). Fixed portions that do not move with respect to the mounting shaft 21 are a fixed flange 22 and a plurality of fixed flange protrusions 23 that are attached to the outer peripheral side thereof. On the other hand, the movable part movable in a predetermined range in the axial direction with respect to the attachment shaft 21 is a plurality of push rings 26, four fixed pins 27, a movable flange 24, and a plurality of movable parts attached to the outer peripheral side of the movable flange 24. This is a flange protrusion 25. Since these movable parts are fixed to each other, they move together in the axial direction. Further, a compression spring 28 is interposed between the movable part and the fixed part. The compression spring 28 is interposed between the fixing flange 22 as a fixing portion and the push ring 26, and urges the push ring 26 to move upward in the axial direction.

  In the vicinity of the center of the push ring 26, a through hole 26a for penetrating the mounting shaft 21 is formed. The through hole 26 a is not fixed to the mounting shaft 21, and is held so that the through hole 26 a can slide with respect to the mounting shaft 21. As for the movable range in the axial direction of the push ring 26, the upper limit is the state shown in FIG. 2 in the upward direction, that is, the state in which the movable flange 24 abuts against the fixed flange 22. The downward movable range of the push ring 26 is from the upper surface of the fixed flange 22 to the vicinity of the compression limit of the compression spring 28. Note that the push ring 26 and the movable flange 24 are fixed to each other by a fixing pin 27 arranged at equal intervals (for example, every 90 degrees) in the circumferential direction. Four through holes 22c are formed in the circumferential direction of the fixed flange 22, and the fixed pin 27 extends from the push ring 26 side to the movable flange 24 side through the through hole 22c. The through hole 22c and the fixing pin 27 are slidable with each other and are not fixed. Further, a stepped portion 26b having a stepped shape was formed around the through hole 26a of the push ring 26. By comprising in this way, the length of fitting with the attachment axis | shaft 21 can be taken long, and a weight increase can be suppressed.

  The body 11 of the core bit 10 is formed in a cylindrical shape, and four notches 13 are formed at the upper end thereof. The cutout portion 13 includes an axial cutout 13a (axial portion) extending downward in the axial direction from the upper end surface of the body 11, and a first circumferential cutout 13b extending in the circumferential direction from the middle of the axial cutout 13a ( 1st circumferential direction part) and the 2nd circumferential notch 13c (2nd circumferential direction part) extended in the circumferential direction from the lower end of the axial notch 13a are formed. The circumferential direction in which the first circumferential cutout 13b and the second circumferential cutout 13c extend from the axial cutout 13a is determined according to the rotation direction of the mounting shaft 21 during the drilling operation. It is important to set the core bit 10 so as not to loosen with respect to the shank portion 20. The fixed flange protrusion 23 is engaged with the first circumferential notch 13b. Similarly, the movable flange protrusion 25 is engaged with the second circumferential notch 13c.

  The shank portion 20 is attached to the core bit 10 at the upper end of the fixed flange 22 by aligning the circumferential positions of the fixed flange protrusion 23 and the movable flange protrusion 25 of the shank portion 20 with the position of the axial notch 13a. The flange 22b and the upper end of the body 11 are brought into contact with each other. In this state, by pushing the push ring 26 downward against the urging force of the compression spring 28, the movable flange 24 is moved in the direction of the core bit 10 (the direction of arrow 2 in the figure). When the axial distance between the fixed flange protrusion 23 and the movable flange protrusion 25 is substantially equal to the axial distance between the first circumferential notch 13b and the second circumferential notch 13c, the shank portion 20 is connected to the core bit 10. Is rotated by a predetermined angle in the direction of arrow 3. The fixed flange protrusion 23 and the movable flange protrusion 25 are arranged at the same angular position. When the push ring 26 is rotated, the fixed flange 22 is fixed via the movable flange 24 fixed by the fixed pin 27 and the through hole 22c of the fixed flange 22. Rotate together. As a result, the fixed flange protrusion 23 comes into contact with the end portion of the first circumferential cutout 13b, and the movable flange projection 25 comes into contact with the end portion of the second circumferential cutout 13c. When the downward pressing of the push ring 26 is released in this state, the movable flange 24 and the movable flange protrusion 25 are moved upward by the force of the compression spring 28, and the movable flange protrusion 25 is engaged with the lock portion 13g. This prevents the movable flange 24 from rotating in the circumferential direction.

  The second circumferential notch 13c is formed to be slightly wider than the movable flange protrusion 25 so that the operator can easily rotate the push ring 26 and the movable flange 24 while being pushed down. For this reason, the operability when the core bit 10 is attached to and detached from the shank portion 20 is good. On the other hand, the first circumferential cutout 13b and the lock portion 13g are configured to have substantially the same width as the fixed flange protrusion 23 and the movable flange protrusion 25 so as not to cause backlash as much as possible during work. For this reason, since the core bit 10 is firmly held against the shank portion 20 during the drilling operation, the operation can be performed without causing rattling.

  As described above, the core bit 10 is fixed to the shank portion 20 by engaging the fixed flange protrusion 23 and the movable flange protrusion 25 provided on the fixed flange 22 and the movable flange 24 with the notch portion 13, so that the core bit 10 is fixed. It can be stably fixed to the shank portion 20. In addition, since the direction in which the push ring 26 is pushed during attachment is the same as the attachment direction of the shank portion 20 with respect to the core bit 10, it is easy for the operator to apply force and the core bit set 1 that can be easily attached can be realized.

  Next, the structure of the movable part of the shank part 20 is demonstrated using FIG.3 and FIG.4. FIG. 3 is a perspective view showing the component configuration of the movable part of the shank portion 20 and shows a state before assembling the components. The movable flange 24 is a circular metal member having a predetermined thickness in the axial direction, and a through hole 24a for penetrating the tip portion of the mounting shaft 21 is formed at the center. Holes 24b are formed at four locations on the upper surface of the movable flange 24, and the tip of the cylindrical fixing pin 27 is fixed by press-fitting. At four positions on the side surface of the movable flange 24, a cylindrical hole 24c formed in the radial direction is formed, and a movable flange protrusion 25 is formed in the hole 24c. How to form the movable flange protrusion 25 is arbitrary, but in this embodiment, it is formed by press-fitting a cylindrical spring pin into the hole 24c. Since the main purpose of the movable flange protrusion 25 is to be fitted to the notch 13, the movable flange protrusion 25 is formed integrally with the movable flange 24 by casting or shaving of metal without using a separate spring pin or the like. Alternatively, it may be manufactured according to other manufacturing directions. Although the movable flange 24 and the fixing pin 27 are fixed by press-fitting, female screws are formed inside the four holes 24b on the upper surface, and male screws (not shown) are formed at the lower end of the fixing pin 27. However, it may be screwed to a female screw formed in the hole 24b.

  The push ring 26 is a circular metal member having a predetermined thickness in the axial direction, and a through hole 26a for allowing the attachment shaft 21 to pass therethrough is formed near the center. In FIG. 3, the cylindrical outer peripheral surface of the push ring 26 is smoothly formed. However, a groove or the like is formed in the vertical direction so that the operator does not slip when the push ring 26 is rotated. Also good. Although not visible from the viewpoint of FIG. 3, cylindrical holes extending in the axial direction are formed at four locations on the lower surface of the push ring 26, and the tips (upper ends) of the four fixing pins 27 are formed in the holes. Press fit.

  The state assembled in this way is shown in FIG. For the sake of explanation, FIG. 4 shows a state in which only the movable part of the shank portion 20 is assembled, but in reality, a fixed flange 22 (see FIG. 2) is provided between the push ring 26 and the movable flange 24. Assembled in position. At that time, the fixing pin 27 is passed through the through hole 22c of the fixing flange 22, and the movement in the axial direction is not hindered. Similarly, the push ring 26 is positioned so that the through hole 26a penetrates the mounting shaft. With the configuration described above, the push ring 26 can be configured to move in the axial direction integrally with the movable flange 24 by the four fixed pins 27 penetrating the fixed flange 22.

  Next, the operation of the shank unit 20 will be described with reference to FIGS. FIG. 5 is a front view showing a free state of the shank portion 20. The push ring 26 and the movable flange 24 are fixed by a fixed pin 27 and are urged in a predetermined direction (in a direction in which the push ring 26 and the fixed flange 22 are separated) by a compression spring 28, so that the movable flange 24 is fixed. It moves in the direction of the arrow with respect to the flange 22 and the mounting shaft 21, and the state shown in FIG. At this time, the axial distance between the center points of the fixed flange protrusion 23 and the movable flange protrusion 25 is a. The outer peripheral surface of the fixed flange 22 is in contact with the inner peripheral surface of the body 11 of the core bit 10, but the outer diameter of the portion in contact with the inner peripheral wall of the body 11 is d3. The outer peripheral surface of the movable flange 24 is formed to have a slightly smaller diameter than the outer diameter d3 of the fixed flange 22, and is configured to have a minute gap with the inner peripheral surface of the body 11 of the core bit 10, so that the frictional resistance during mounting Can be reduced. Near the upper end of the fixing flange protrusion 23, a flange 22b for pressing the upper end surface, which is an opening on the rear end side of the body 11 of the core bit 10, is formed. It is preferable that the outer diameter of the flange portion 22b is substantially the same as that of the body 11 of the core bit 10. Further, the outer diameter d3 is larger than the outer diameter d2 of the push ring 26.

  FIG. 6 is a front view showing a state when the shank portion 20 of FIG. 2 is engaged. When the operator pushes the push ring 26 downward while holding the body 11 and moves the push ring 26 in the direction of the arrow in a state where the collar portion 22b is in contact with the body 11 of the core bit 10, the connection by the fixing pin 27 is performed. Therefore, the movable flange 24 also moves in the direction of the arrow. At this time, since the fixed flange 22 does not move relative to the mounting shaft 21, the fixed flange 22 and the movable flange 24 are separated from each other, and the axial distance between the center points of the fixed flange protrusion 23 and the movable flange protrusion 25 is approximately b. This distance b is configured to be at least larger than the axial distance between the first circumferential notch 13b and the second circumferential notch 13c shown in FIG. At this time, the movable flange 24 is lowered to the vicinity of the lower end 21 a of the mounting shaft 21.

  With the above configuration, it is possible to realize a core bit set in which the core bit 10 and the shank portion 20 can be attached and detached with one touch, and there is no backlash at the time of drilling work. In order to fix the shank part 20 to the core bit 10, the fixed flange protrusion 23 and the movable flange protrusion 25 are inserted in alignment with the axial notch 13 a of the notch part 13 provided at the upper end of the body 11, and The push ring 26 is pushed downward against the urging force of the compression spring 28 in a state where the portion 22 b is abutted against the upper end surface of the body 11. At the same time as the push ring 26 is pushed down, the movable flange 24 moves downward, and the movable flange protrusion 25 becomes movable to the second circumferential notch 13c. In this state, when the push ring 26 is rotated clockwise, the movable flange protrusion 25 can be moved to the deepest lock position along the second circumferential notch 13c. At this time, since the fixing flange 22 also moves clockwise, the fixing flange protrusion 23 can also move to the innermost part of the first circumferential notch 13b. Thereby, even when the shank portion 20 is lifted upward during the drilling operation, it is possible to prevent the upper surface of the fixing flange protrusion 23 and the upper surface of the first circumferential notch 13b from coming into contact with each other and the fixing flange 22 to be rattled. . Further, since the lock of the core bit 10 and the shank portion 20 is not released unless the push ring 26 is artificially operated, the core bit 10 can be stably held. Furthermore, since the core bit 10 can be attached / detached by pushing the push ring 26 downward, the operability is good, and the attaching / detaching work can be easily performed even when the core bit 10 remains attached to the power tool body.

  Next, another shape of the notch formed in the core bit 10 will be described with reference to FIGS. FIG. 7 is a partial side view showing the notch 63 formed in the core bit 10 according to the second embodiment (when mounted). The basic shape of the notch 63 is substantially the same as that of the notch 13 in FIG. 2, and the notch 13 in FIG. The width of the inlet portion of the axial cutout 63a (first circumferential width w1) is formed so as to be wider than the cutout portion 13 of FIG. The other portions, the second circumferential width w2, and the shapes and sizes of 63b to 63g are exactly the same as the corresponding notch portions 13. The first circumferential cutout 63b and the second circumferential cutout 63c are arranged continuously with the axial cutout 63a so as to be the same entrance.

  In the first circumferential cutout 63b, the lower edge 63e is horizontal, but the upper edge 63d is slightly inclined, and as the distance from the axial cutout 63a increases, the vertical width of the circumferential cutout 63b becomes narrower. Formed as follows. The position of the fixing flange protrusion 23 in FIG. 7 is a state during cutting using the core bit 10. The second circumferential notch 63c has exactly the same shape as the second circumferential notch 13c shown in FIG. At the end in the circumferential direction away from the axial notch 63a, a recess 63f that is recessed upward in the axial direction is formed. The position of the movable flange protrusion 25 in FIG. 7 is a state during cutting using the core bit 10. When the operator releases the push ring 26 from being pushed downward in the axial direction, the movable flange protrusion 25 is moved upward by the action of the compression spring 28 and is stably held at the position shown in FIG. . At this time, a part of the side near the axial notch 63a in the rotational direction is held by the lock portion 63g, so that the movable flange protrusion 25 is stably held without rattling in the rotational direction.

  FIG. 8 is a side view showing the shape of the notch formed in the core bit 10 according to the second embodiment, and is a view for explaining the state at the time of removal. When removing the core bit 10 from the shank part 20, the body 11 is rotated from the state shown in FIG. 1 in the direction opposite to that when the body 11 is attached while pressing the push ring 26 of the shank part 20 downward while holding the body 11 with one hand. By this rotation, the fixing flange protrusion 23 moves from the position of 123a to 123c and 123e. An arrow 122 connecting the center points of the positions 123a, 123c, and 123e indicates the movement locus of the center point of the fixed flange protrusion 23. As can be understood from the arrow 122, the fixed flange protrusion 23 moves only in the circumferential direction from the point 123a to 123e without moving in the axial direction.

  On the other hand, the movable flange protrusion 25 is different from the movement of the fixed flange protrusion 23. First, the push ring 26 is moved downward to move from the position 125a to the position 125b. Due to this movement, the movable flange protrusion 25 does not come into contact with the latching portion 63g, so that the rotation of the body 11 is started in this state. When the rotation reaches the position of 125c, 125d from the position of 125b, the movable flange protrusion 25 comes into contact with the edge of the groove-direction notch 63a, so that no further rotation is possible. Therefore, when the operator releases the push ring 26 downward in the axial direction, the movable flange protrusion 25 is automatically moved to the position 125e by the force of the compression spring. The positional relationship at this time (the positions of 123e and 125e) is the position of the distance a in the state of FIG. 5 and the fixed flange 22 and the movable flange 24 are in contact with each other by the compression spring 28. Normally, the core bit 10 can be easily removed by moving the body 11 away from the shank portion 20 in the axial direction from this state. However, the flange portion 22b and the fixed flange 22 are configured to be in close contact with the body 11 of the core bit 10 in order to ensure the mounting accuracy, and further, dust enters the joint surface and the fixed flange 22, the movable flange 24, and the core bit 10 The relative movement of the camera may not be smooth and may be difficult to remove. Therefore, in the second embodiment, the inclined portion 63h is formed so that the core bit 10 can be separated from the shank portion 20 smoothly.

  When the fixed flange protrusion 23 in FIG. 8 is at the position 123e and the movable flange protrusion 25 is at the position 125e, the width of the axial notch 63a in the rotational direction is widened, so the core bit 10 is further rotated. It is possible. In this rotation, the operator does not need to press the push ring 26 downward in the axial direction, and simply rotates the core bit 10 relative to the shank portion 20. Then, since the movable flange protrusion 25 at the position of 125e hits the inclined portion 63h, the movable flange protrusion 25 is guided by the inclined portion 63h and moves obliquely upward. This state is indicated by the movement locus of the last part of the arrow 124. At this time, since the upper surface of the movable flange 24 is in close contact with the lower surface of the fixed flange 22 as in the state of FIG. 5, the movable flange protrusion 25 is guided by the inclined portion 63h and moves obliquely upward, thereby moving the fixed flange. The protrusion 23 also moves obliquely upward. As a result, the core bit 10 moves in a direction away from the shank portion 20, so that the core bit 10 can be easily moved away from the shank portion 20 simply by rotating. Thus, in the second embodiment, the core bit 10 can be separated from the shank portion 20 by rotating the core bit 10 using the inclined portion 63h, so that the core bit 10 can be removed with a small force.

  As described above, in the second embodiment, when removing the core bit 10 and the shank portion 20, if the push ring 26 is rotated counterclockwise while the push ring 26 is pushed down, the movable flange protrusion 25 is formed on the axial notch 63a. The core bit 10 and the shank portion 20 can be easily unlocked. Furthermore, after the core bit 10 and the shank part 20 are unlocked, the core bit 10 can be moved away from the shank part 20 in the axial direction by rotating the core bit 10 only slightly. It becomes easy to remove, and a core bit set for a power tool that is easy to use can be realized.

  As mentioned above, although this invention was demonstrated based on the Example, this invention is not limited to the above-mentioned Example, A various change is possible within the range which does not deviate from the meaning. For example, in the above-described embodiment, the portion of the core bit 10 to which the fixed flange protrusion 23 and the movable flange protrusion 25 are locked is realized by the notch formed in the body 11, but the inner wall of the body 11 is not limited to the notch. It may be formed on the side by a groove formed outward in the radial direction. Further, not all of the latching portions are formed by grooves, but only the portions corresponding to the axial cutouts 13a are used as the grooves and correspond to the first circumferential cutouts 13b and the second circumferential cutouts 13c. Only the portion may be formed by a notch or a hole penetrating from the inner wall side to the outer wall side. In this way, if the portions corresponding to the first circumferential cutout 13b and the second circumferential cutout 13c are formed with through holes, the fixed flange projection 23 and the movable flange projection 25 are securely locked to predetermined positions. As a result, it is possible to realize an easy-to-use core bit set.

DESCRIPTION OF SYMBOLS 1 Core bit group 10 Core bit 11 Body 12 Blade part 13 Notch part 13a Axial notch 13b 1st circumferential notch 13c 2nd circumferential notch 20 Shank part 21 Attachment shaft 21a (attachment shaft) lower end 22 Fixation Flange 22b flange 22c through hole 23 fixed flange protrusion 24 movable flange 24a through hole 24b, 24c hole 25 movable flange protrusion 26 push ring 26a (push ring) through hole 26b (push ring) stepped portion 27 fixed pin 28 compression Spring 63 Notch 63a Axial notch 63b First circumferential notch 63c Second circumferential notch 63d Upper edge 63e Lower edge 63f Depression 63g Locking part 63h Inclined part

Claims (8)

A core bit set composed of a shank portion attached to a power tool and a cylindrical core bit fixed to the shank portion in a detachable manner,
The shank portion is
A mounting shaft for mounting on the power tool;
A fixing member fixed to the mounting shaft and having a protrusion;
A movable member provided so as to be movable in the axial direction with respect to the fixed member, and having a protrusion;
A spring for urging the movable member in the axial direction relative to the fixed member;
The core bit is
A blade provided at the lower end of the cylindrical body;
First engaging means for engaging with the protrusion of the movable member;
A core bit set for a power tool, characterized in that a projection portion of the fixing member and a second engaging means for engaging in the axial direction are provided. The first engaging means and the second engaging means are notches or grooves formed in the body,
2. The power tool core bit set according to claim 1, wherein circumferential positions of notches or groove entrance portions where the protrusions of the fixed member and the movable member are guided are the same. The notch or groove has an axial portion extending in the axial direction from the opening end of the body, a first circumferential portion extending in the circumferential direction from the middle of the axial portion, and a first portion extending in the circumferential direction from the lower end of the axial portion. Formed from two circumferential portions,
The locking part which restricts the movement of the circumferential direction is provided in the terminal of the said 2nd circumferential direction part by moving the protrusion part of the said movable member to a small distance in an axial direction, The characterized by the above-mentioned. Core bit set for power tools.   The core bit set for a power tool according to any one of claims 1 to 3, wherein the fixing member has a flange portion in contact with an upper edge portion of the body of the core bit. A push ring is provided above the fixed member to move the movable member,
Fixing the push ring to the movable member located below the fixing member by a plurality of pins penetrating through a hole formed in the fixing member;
The core bit set for a power tool according to claim 4, wherein the spring is interposed between the push ring and the fixing member.   6. The power according to claim 1, wherein the protrusion of the fixed member and the protrusion of the movable member are arranged at the same angular position and rotate together in the axial direction. Core bit set for tools. A cylindrical body;
A blade provided at one end of the body;
A protrusion locking means for fixing the body to the shank portion by engaging with a fixed member of the shank portion and a protruding portion of the movable member,
The protrusion locking means is a notch or groove formed in the body,
The notch or groove has an axial portion extending in the axial direction from the opening end of the body, a first circumferential portion extending in the circumferential direction from the middle of the axial portion, and a first portion extending in the circumferential direction from the lower end of the axial portion. Formed from two circumferential portions,
The core bit according to claim 1, wherein a lock portion is provided at a distal end of the second circumferential direction portion to limit movement in the circumferential direction by moving the protrusion of the movable member by a minute distance in the axial direction. The axial portion has a first circumferential width on the inlet side, a second circumferential width narrower than the first circumferential width on the back side, and the first to second circumferential directions. The connecting portion of the width portion is formed with an oblique cutout or groove, and when the body is rotated by the contact of the protrusion of the movable member, a component force is generated that moves the core bit away from the shank portion. The core bit according to claim 7, wherein the core bit is formed as described above.

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