Core Bit

Abstract

This provides a core bit that can accurately drill holes to a predetermined depth without interrupting a series of operations. [Solution] The present invention is a core bit 10 used for machining a workpiece, having a cylindrical body and a cutting edge portion made of a diamond tip fixed to the tip of the body, and is equipped with a ring-shaped depth adjustment member 20 attached to the outer circumference of the body to adjust the drilling depth. The depth adjustment member 20 is characterized by comprising a ring-shaped main body portion 21 having a stopper surface 23 on one surface that restricts the drilling depth, and an engagement portion provided on the main body portion 21 so as to be able to protrude from the main body portion 21 toward the outer circumference of the body and which can engage with and disengage from the outer circumference of the body.

Description

Technical Field

[0001] The present invention relates to a core bit for core drills used for drilling into concrete structures, stone materials, asphalt, tiles and the like (these are collectively referred to as workpieces in the present specification). Background Art

[0002] Conventionally, various drilling devices for drilling holes in workpieces such as concrete have been proposed. In this drilling device, a core bit provided at the tip of a drill is rotationally driven to drill the workpiece.

[0003] In addition, when drilling a hole of a predetermined depth with this drilling device, for example, marking is applied to a position corresponding to the predetermined depth on the side surface of the core bit, and the workpiece is drilled by the core bit until the marking reaches the drilled surface of the workpiece.

[0004] On the other hand, the following Patent Document 1 proposes a drilling device for drilling a hole of a predetermined depth in a workpiece. This drilling device includes a support column erected on an upper part of the workpiece, and a graduated scale is provided on the support column. In this drilling device, the moving distance of the core bit (that is, the depth of the hole) can be read by the scale, and a hole of a predetermined depth can be obtained. Prior Art Literature Patent Literature

[0005] Patent Document 1 Japanese Unexamined Patent Publication No. Hei 7-299817 Summary of the Invention Problem to be Solved by the Invention

[0006] In conventional methods of drilling holes to a predetermined depth in a workpiece, marking the core bit can be problematic. During drilling, dust or other particles can make it difficult to see the markings, or the markings may fade and become illegible. Furthermore, this method requires interrupting the drilling process to check the position of the markings relative to the drilled surface, which is time-consuming. Moreover, this method carries the risk of drilling beyond the markings.

[0007] Furthermore, devices capable of monitoring the movement distance of the core bit, such as the drilling device described in Patent Document 1, are expensive and difficult to introduce easily. In addition, although methods such as attaching markers or stoppers to the support column of the core drill can be considered, even with such methods, it is necessary to set the drilling depth after attaching the core bit to the core drill body, which is time-consuming.

[0008] This invention was devised in view of the above-described circumstances, and aims to provide a core bit that can accurately drill holes to a predetermined depth without interrupting a series of operations. [Means for solving the problem]

[0009] The present invention relates to a core bit used for drilling a workpiece, having a cylindrical body and a cutting edge fixed to the tip of the body, wherein the core bit is equipped with a ring-shaped depth adjustment member attached to the outer circumference of the body to set the drilling depth, and the depth adjustment member is equipped with a ring-shaped main body portion having a stopper surface on one side that restricts the drilling depth, and an engaging portion provided on the main body portion so as to be able to protrude from the main body portion toward the outer circumference of the body and can engage with and disengage from the outer circumference of the body.

[0010] In the core bit of the present invention, the engaging portion comprises an engaging tip portion at its tip that engages with the body and a cylindrical screw member having male threads on its outer circumference. Preferably, the main body portion is provided with a through hole that penetrates from the outer surface to the inner surface of the main body portion and into which the screw member is inserted, and the inner circumference of the through hole is provided with female threads into which the male threads of the screw member are screwed.

[0011] In the core bit of the present invention, an elastic ring member is provided on the outer circumference of the main body portion and covers the rear end of the screw member, and it is desirable that the ring member elastically contacts the rear end of the screw member so as to press the screw member against the outer circumference of the body.

[0012] In the core bit of the present invention, it is preferable that the stopper surface comprises a contact surface that abuts against the surface of the workpiece and a depth confirmation surface that is recessed from the contact surface and allows for confirmation of the drilling depth. [Effects of the Invention]

[0013] The core bit of the present invention, having the above-described features, can accurately drill holes to a predetermined depth without interrupting a series of operations. [Brief explanation of the drawing]

[0014] [Figure 1] A front view showing a core drill according to an embodiment of the present invention. [Figure 2] Figure 1 is a schematic diagram of the appearance of a core bit that is attached to a core drill. [Figure 3] Figure 2 is a partially enlarged cross-sectional view of the depth adjustment member attached to the core bit. [Modes for carrying out the invention]

[0015] The core bit 10 of an embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows a core drill 1 to which a core bit 10 is attached. As shown in Figure 1, the core drill 1 comprises a base 3 that is removably fixed to the workpiece 2, a support column 5 that protrudes upward from the base 3 and has a rack 4 attached to it, a main body 6 that is slidably mounted on the support column 5 and has a pinion (not shown) that meshes with the rack 4, a shaft 7 that is rotatably supported on the main body 6, and a motor 8 that rotates the shaft 7.

[0016] The core bit 10, which is removably attached to the shaft 7, includes a cylindrical body 11, a coupling 12 integrally provided at the rear end of the body 11 (corresponding to the upper end in the height direction when in use) and screwed onto the shaft 7 for connection, and a cutting edge portion 13 fixed to the tip of the body 11 (corresponding to the lower end in the height direction when in use) and consisting of a tip (diamond tip) formed of diamond abrasive grains.

[0017] Figure 2 shows a schematic diagram of the core bit 10 when it has been removed from the coupling 12. As shown in Figure 2, in this embodiment, a ring-shaped depth adjustment member 20, which acts as a stopper to set the drilling depth during processing, is loosely fitted to the outer circumference of the body 11.

[0018] Figure 3 shows a partially enlarged cross-sectional view of the depth adjustment member 20. As shown in Figure 3, the depth adjustment member 20 has a ring-shaped main body 21. The main body 21 has an inner circumferential surface 22 with an inner diameter equal to or slightly larger than the diameter of the body 11 (shown in Figure 2), stopper surfaces 23, 23 facing each side of the body 11 in the axial direction (i.e., the upper or lower side), and an outer circumferential surface 24. One of these stopper surfaces 23, 23 (the downward-facing surface in this embodiment) can restrict the drilling depth as described later. The main body 21 is provided with through holes 25 that penetrate from the outer circumferential surface 24 to the inner circumferential surface 22. Multiple through holes 25 are provided, for example, in the circumferential direction of the main body 21 (the direction along the outer circumference of the body 11). In this embodiment, the main body 21 has three through holes 25 spaced at an angle of approximately 120° with respect to the circumferential direction.

[0019] Into this through-hole 25, a columnar screw member 26 is inserted as an engaging portion capable of engaging with and disengaging from the outer periphery of the body 11. A male screw is provided on the outer periphery of the screw member 26, and a female screw screwed with the male screw is provided on the inner periphery of the through-hole 25. An engaging distal end portion 26a that bites into and engages with the outer periphery of the body 11 is provided at the distal end portion of the screw member 26, and a hexagonal hole (not shown) for rotating the screw member 26 using a rotary tool (not shown) or the like is provided at the rear end portion 26b. This hexagonal hole is merely an example, and the present invention is not limited thereto. Further, neither the male screw nor the female screw needs to be provided over the entire length of the through-hole 25 or the screw member 26. The engaging distal end portion 26a may be a flat surface, may have a shape along the circumference of the outer periphery of the body 11, or may be tapered so as to bite into the outer periphery of the body.

[0020] On the outer peripheral surface 24 of the main body portion 21, a ring groove 27 having a width covering the through-hole 25 and a shallow depth is provided. As shown in Figures 2 and 3, an elastic ring member 30 is fitted into the ring groove 27. The ring member 30 is formed of an elastic material such as rubber, for example. Since the inner diameter of the ring member 30 is slightly smaller than the diameter of the bottom surface of the ring groove 27, a force acts in a direction to elastically press the ring member 30 against the ring groove 27 of the main body portion 21, so that the ring member 30 is firmly held in the ring groove 27. In this way, the ring member 30 covers and hides the screw member 26 to function as a protective cover, which can prevent the rear end portion 26b of the screw member 26 from protruding and being exposed. Thereby, safety during operation is improved, and adhesion and accumulation of dust, processing dust and the like on the screw member 26 can be prevented.

[0021] Also, the length of the screw member 26 is slightly larger than the length of the through hole 25. Accordingly, when the screw member 26 is inserted into the through hole 25, and the engaging distal end portion 26a of the screw member 26 bites into and engages with the outer peripheral surface of the body 11, the screw member 26 has such a length that both the engaging distal end portion 26a and the rear end portion 26b slightly protrude from the through hole 25 (for example, 5 mm or less). In addition, since the rear end portion 26b slightly protrudes from the bottom surface of the ring groove 27, the inner periphery of the ring member 30 comes into contact with the rear end portion 26b of the screw member 26 and presses the screw member 26 toward the body 11, so a loosening prevention effect for the screw member 26 can also be expected.

[0022] Although the ring groove 27 is provided to have a dimension for fitting the ring member 30 therein, the ring groove 27 may be omitted. Instead, the screw member 26 may be provided such that its rear end portion 26b slightly protrudes from the outer peripheral surface 24, and the ring member 30 may be provided to cover the entire outer peripheral surface 24 including the rear end portion 26b and even cover a part of the stopper surface 23. In this case, since the entire outer peripheral surface 24 of the main body portion is covered by the ring member 30, exposure of the metal corner portions of the main body portion can be prevented, further improving safety.

[0023] The stopper surface 23 includes a contact surface 23a that comes into contact with the surface of the workpiece 2, and a depth confirmation surface 23b that is recessed from the contact surface 23a with a step and indicates the drilling depth. The depth confirmation surface 23b is provided in a ring shape over the entire outer circumference of the stopper surface 23, so that the drilling depth can be confirmed from any direction. Since the contact surface 23a is likely to have its surface damaged due to contact with the drilled surface of the workpiece 2, the depth confirmation surface 23b is provided at a position recessed from the contact surface 23a. Although the contact surface 23a and the depth confirmation surface 23b are provided with a step, the contact surface 23a and the depth confirmation surface 23b may be connected by an inclined surface in order to eliminate the step edge.

[0024] Furthermore, since the depth confirmation surface 23b is recessed from the contact surface 23a by a step and provided on the outer peripheral side, dust and debris are less likely to accumulate on this depth confirmation surface 23b, and even if they accumulate, they can be discharged to the outside immediately, which is suitable for depth confirmation.

[0025] As the present invention is configured as described above, when forming a hole of a predetermined depth on the drilled surface of the workpiece 2 as shown in Figure 1, first, the drilling depth adjustment member 20 is attached to the core bit 10 such that the depth confirmation surface 23b (shown in Figure 2 or Figure 3) of the stopper surface 23 of the depth adjustment member 20 is positioned at a length dimension from the tip of the core bit 10 to the predetermined depth.

[0026] Next, by moving the core drill 1 while rotating the core bit 10, a hole determined by the outer diameter of the core bit 10 is formed in the surface to be drilled. After this, the drilling is completed when the contact surface 23a (shown in Figure 2 or Figure 3) of the stopper surface 23 of the drilling depth adjustment member 20 comes into contact with the surface to be drilled, thereby forming a hole of a predetermined depth.

[0027] As a result, it is not necessary to check the position of the core bit 10 markings and the surface to be drilled during drilling, allowing drilling to be performed without interrupting the series of operations. Furthermore, since the drilling depth is kept constant by the depth adjustment member 20, it is possible to accurately drill holes to a predetermined depth.

[0028] Furthermore, according to the present invention, the depth adjustment member 20 can be detachably attached to the outer circumference of the core bit 10, allowing the drilling depth to be set in advance, and the position of the depth adjustment member can be visually confirmed even during drilling. The depth adjustment member 20 abuts against the surface of the workpiece 2 when the cutting edge portion 13 of the core bit 10 reaches a predetermined lowest point, preventing the core bit 10 from penetrating further into the workpiece 2, thus preventing drilling beyond this depth. In addition, in the core bit 10 of this embodiment, the depth adjustment member can be easily moved in the longitudinal direction of the body by removing the ring member 30 and loosening the screw member 26, so the drilling depth can be easily changed.

[0029] As shown in Figure 3, in this embodiment, stopper surfaces 23, 23 are provided on both sides, but it is also acceptable to have them on only one side. Furthermore, although the rear end 26b of the screw member 26 is configured to protrude slightly from the through hole 25, the rear end 26b of the screw member 26 may be configured to be flush with or slightly recessed from the through hole 25, so that the inner circumference of the ring member 30 fits into the through hole 25 and pushes in the rear end 26b of the screw member 26. The depth adjustment member 20 of the present invention functions as a stopper by being fitted onto the outer circumference of the core bit 10, and can be used with existing core bits 10. The core bit 10 of this embodiment can be used with both dry and wet core drills. [Industrial applicability]

[0030] The present invention is advantageously applicable to core bits for core drills used for drilling into concrete structures, stone, asphalt, tiles, and the like. [Explanation of Symbols]

[0031] 1 Core Drill 2 Work material 10 Core Bits 11 Body 20 Depth adjustment member 21 Main body 23 Stopper surface 23a Contact surface 23b Depth confirmation surface 25 Through holes 26 Screw component 27 Ring groove 30 Ring component

Claims

1. A core bit having a cylindrical body and a cutting edge fixed to the tip of the body, used for drilling a workpiece, The body is equipped with a ring-shaped depth adjustment member attached to its outer circumference for setting the drilling depth, The depth adjustment member is A ring-shaped main body having a stopper surface on one side that regulates the drilling depth, An engaging portion is provided on the main body so as to be able to protrude from the main body toward the outer circumference of the body, and is capable of engaging with and disengaging from the outer circumference of the body, A core bit characterized by having the following features.

2. In the core bit according to claim 1, The engagement portion comprises an engagement tip that engages with the body at its tip, and a cylindrical screw member having male threads on its outer circumference. The main body portion is provided with a through hole that penetrates from the outer circumferential surface to the inner circumferential surface of the main body portion, into which the screw member is inserted. A core bit characterized in that the inner circumference of the through hole is provided with a female thread into which the male thread of the screw member is screwed.

3. In the core bit according to claim 2, The main body is provided with an elastic ring member that covers the rear end of the screw member, The core bit is characterized in that the ring member elastically contacts the rear end of the screw member so as to press the screw member against the outer circumference of the body.

4. In the core bit according to claim 1, The core bit is characterized in that the stopper surface comprises a contact surface that abuts against the surface of the workpiece and a depth confirmation surface that is recessed from the contact surface and is used to confirm the drilling depth.

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