Drill guard and manufacturing method of drilled item

Abstract

To avoid work of protecting a work material with a cover or the like in order to prevent damage of the work material when a drill is broken in a case where drilling is performed to the work material with the drill.SOLUTION: A drill guard according to an embodiment is attached to a positioning drill bush, which has a through hole for inserting a drill and is inserted into a positioning through hole to be used, to be used or integrated with the drill bush. The drill guard includes: a cylindrical part having an outer diameter or a maximum width which is larger than an outer diameter in an insertion part of the drill bush for insertion into the positioning through hole; and a coupling part for coupling one end of the cylindrical part to the insertion part of the drill bush. The other end of the cylindrical part is formed as an opening end to allow the drill to be inserted from the opening end side into the through hole of the drill bush. The structure causes fragments of the drill to remain in the cylindrical part while preventing scattering of the fragments when the drill is broken.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] Embodiments of the present invention relate to a drill guard and a method for manufacturing a workpiece to be drilled.

Background Art

[0002] When drilling a workpiece using a drill, it is important to prevent the broken drill from scattering when the drill breaks (see, for example, Patent Document 1). In the assembly work of large parts such as aircraft parts, holes for inserting fasteners such as rivets and bolts are often machined using a drill held by an operator with a hand-held tool rotating device. Therefore, the workpiece is protected in advance with a cover or the like so that the workpiece is not damaged when the drill breaks during the drilling operation.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional method, an operation for the operator to protect the workpiece with a cover or the like is required as a setup before drilling. In particular, when the workpiece is large, such as an aircraft part, the size and weight of the cover for protecting the workpiece become large, and there is a problem that the working time and labor of the operator are increased.

[0005] Therefore, an object of the present invention is to avoid an operation of protecting a workpiece with a cover or the like so that the workpiece is not damaged when the drill breaks when drilling the workpiece with a drill.

Means for Solving the Problems

[0006] ​The drill guard according to an embodiment of the present invention has a through-hole for inserting a drill, and is used by being attached to a positioning drilling bush that is inserted into the positioning through-hole or integrated with the drilling bush. The drill guard has a cylindrical portion having an outer diameter or a maximum width larger than the outer diameter of the insertion portion of the drilling bush for insertion into the positioning through-hole, and a connecting portion for connecting one end of the cylindrical portion to the insertion portion of the drilling bush. By making the other end of the cylindrical portion an open end, the drill can be inserted into the through-hole of the drilling bush from the open end side, and when the drill breaks, the fragments of the broken drill stay inside the cylindrical portion without scattering.

[0007] In addition, a method for manufacturing a workpiece to be drilled according to an embodiment of the present invention inserts the insertion portion of the drilling bush provided with the above-described drill guard into the positioning through-hole, and inserts the drill into the through-hole of the drilling bush to drill a workpiece to be machined, thereby manufacturing a workpiece to be drilled.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0009] The drill guard according to the embodiment of the present invention and the manufacturing method of the work piece to be drilled will be described with reference to the accompanying drawings.

[0010] (First Embodiment) (Configuration and Function) FIG. 1 is a longitudinal sectional view showing the usage state of the drill guard 1 according to the first embodiment of the present invention, FIG. 2 is a front view of the drill guard 1 shown in FIG. 1, FIG. 3 is a top view of the drill guard 1 shown in FIG. 1, and FIG. 4 is a bottom view of the drill guard 1 shown in FIG. 1.

[0011] The drill guard 1 is a protective device for receiving the broken drill 2 when the drill 2 breaks during the drilling of the workpiece W. The drill guard 1 is used by being attached to the drilling bush 3. Therefore, the drill guard 1 and the drilling bush 3 form a drilling jig, and the drill guard 1 and the drilling bush 3 may be used as components of the drilling jig.

[0012] The drilling bush 3 is a bush for positioning the drill 2 with respect to the workpiece W when the operator drills the workpiece W with the drill 2 attached to a hand-held tool rotating device having a motor and a rotor such as an air motor, an electric motor, or a hydraulic motor. The drilling bush 3 for positioning the drill 2 is sometimes called a replacement bush, a drill guide bush, or a drilling guide bush.

[0013] The piercing bush 3 is used when the hand-held tool rotating device does not have a feeding function in the tool axis direction of the drill 2. Therefore, the feeding operation of the drill 2 in the tool axis direction is performed by the operator pushing the drill 2 together with the tool rotating device toward the workpiece W. At this time, the piercing bush 3 guides the feeding operation of the drill 2 in the tool axis direction. That is, the advancing direction of the drill 2 is restricted by the piercing bush 3.

[0014] The piercing bush 3 has a through-hole 3A for inserting the drill 2, and is inserted into a positioning through-hole 5A provided in a positioning jig 5 such as a perforated plate or a drilling table and used. The positioning jig 5 is set on the workpiece W so that the central axis of the positioning through-hole 5A and the central axis of the hole of the workpiece W to be drilled are on the same straight line.

[0015] Therefore, when the piercing bush 3 is inserted into the positioning through-hole 5A, the central axis of the through-hole 3A of the piercing bush 3 is also on the same straight line as the central axis of the hole of the workpiece W to be drilled. For this reason, if the drill 2 is guided by the through-hole 3A of the piercing bush 3, the tool axis of the drill 2 can be made to be on the same straight line as the central axis of the hole of the workpiece W to be drilled. That is, the positioning jig 5 and the piercing bush 3 are used to position the drill 2 with respect to the workpiece W, and a hole can be machined with the drill 2 at the target position.

[0016] Incidentally, although the positioning through-hole 5A for inserting the piercing bush 3 may be directly formed in the workpiece W, in most cases, since the positioning through-hole 5A is formed in the positioning jig 5, here, the case where the piercing bush 3 is inserted into the positioning through-hole 5A formed in the positioning jig 5 will be described as an example.

[0017] In the example shown in FIG. 1, the drilling bush 3 has an insertion portion 3B which is a bush body for insertion into the positioning through-hole 5A, and a flange 3C having an outer diameter larger than the outer diameter D of the insertion portion 3B. That is, the drilling bush 3 is a flanged bush. The flange 3C of the drilling bush 3 is sometimes called a head. A pair of parallel flat surfaces 3D for anti-rotation are formed on the typical flange 3C of the drilling bush 3 so that the rotation of the drilling bush 3 can be suppressed by clamping it with a tool, jig, etc. In this case, the outer diameter of the flange 3C is the diameter of the flange 3C at the portion where the flat surfaces 3D are not formed.

[0018] The outer diameter D of the insertion portion 3B of the drilling bush 3 is determined so that the fitting tolerance between the inner diameter of the positioning through-hole 5A formed in the positioning jig 5 such as a perforated plate and the outer diameter D of the insertion portion 3B corresponds to the clearance fit tolerance. In a typical example, H7 on the reference hole side defined by the Japanese Industrial Standards (JIS) is applied to the inner diameter of the positioning through-hole 5A, and g6 on the shaft side is applied to the outer diameter D of the insertion portion 3B of the drilling bush 3.

[0019] For this reason, the insertion portion 3B of the drilling bush 3 can slide axially without play with respect to the positioning through-hole 5A of the positioning jig 5, and the operator can manually insert and remove the insertion portion 3B of the drilling bush 3 into and from the positioning through-hole 5A of the positioning jig 5. Since the maximum diameter of the flange 3C of the drilling bush 3 is larger than the inner diameter of the positioning through-hole 5A, even if the drill guard 1 is not attached to the drilling bush 3, the movement of the drilling bush 3 in the direction toward the workpiece W to be machined is suppressed by the contact of the flange 3C with the surface of the positioning jig 5.

[0020] On the other hand, the drill guard 1 attached to and used with the drilling bush 3 has a cylindrical portion 6 and a connecting portion 7. The cylindrical portion 6 of the drill guard 1 is a cylindrical body having an outer diameter or maximum width larger than the outer diameter D of the insertion portion 3B of the drilling bush 3 and an inner diameter or width capable of inserting the flange 3C of the drilling bush 3 therein.

[0021] The connecting portion 7 of the drill guard 1 is a portion for connecting one end of the cylindrical portion 6 to the insertion portion 3B of the drilling bush 3. For this purpose, the connecting portion 7 can be a plate-like portion having a through-hole 7A for inserting the insertion portion 3B of the drilling bush 3. The connecting portion 7 is arranged so as to partially close the vicinity of the edge of one end of the cylindrical portion 6. In other words, the end portion on the connecting portion 7 side of the cylindrical portion 6 is an open end that opens with a diameter smaller than the maximum value of the inner diameter of the cylindrical portion 6.

[0022] On the other hand, the other end of the cylindrical portion 6 is a simple open end that opens with the same diameter as the inner diameter of the cylindrical portion 6. For this reason, the entire portion including the flange 3C of the drilling bush 3 is inserted into the cylindrical portion 6 of the drill guard 1, and with the flange 3C of the drilling bush 3 arranged inside the cylindrical portion 6 of the drill guard 1, the insertion portion 3B of the drilling bush 3 can be inserted into the through-hole 7A formed in the connecting portion 7 of the drill guard 1. Thereby, the drill guard 1 can be attached to the drilling bush 3.

[0023] In addition, chamfering such as C-chamfering may be performed on the inner surface side of the open end on the rear end side of the cylindrical portion 6 in order to facilitate the insertion of the drilling bush 3. In that case, the diameter in the vicinity of the open end on the rear end side of the cylindrical portion 6 is not constant and gradually increases toward the rear end.

[0024] After the attachment of the drill guard 1 to the drilling bush 3 is completed, the insertion portion 3B of the drilling bush 3 to which the drill guard 1 is attached can be inserted into the positioning through-hole 5A of the positioning jig 5. Since the other end of the cylindrical portion 6 on the rear end side of the drill guard 1 is an open end, the drill 2 can be inserted into the through-hole 3A of the drilling bush 3 from the open end side of the cylindrical portion 6. For this reason, the workpiece W can be drilled with the drill 2 while positioning and guiding the drill 2 with the positioning jig 5 and the drilling bush 3.

[0025] In this case, the operator holds the cylindrical portion 6 of the drill guard 1 by hand, inserts and fits the insertion portion 3B of the drilling bush 3 protruding from the drill guard 1 into the positioning through-hole 5A of the positioning jig 5, and then holds the cylindrical portion 6 of the drill guard 1 by hand even during the drilling of the workpiece W. Therefore, a holding portion 6A composed of a pair of parallel planes can be formed on the outer surface of the cylindrical portion 6 so that the operator can easily hold the cylindrical portion 6 of the drill guard 1, and particularly during the rotation of the drill 2, the rotation of the drill guard 1 can be easily suppressed.

[0026] In addition, a pair of parallel planes forming a rotation suppression portion 6B can be formed on the inner surface of the cylindrical portion 6 to suppress the relative rotational movement between the drill guard 1 and the drilling bush 3. The two planes forming the rotation suppression portion 6B are surfaces for suppressing the rotational movement of the drilling bush 3 by sandwiching a pair of anti-rotation planes 3D formed on the flange 3C of the drilling bush 3.

[0027] Furthermore, after attaching the drill guard 1 to the drilling bush 3, it is also important to suppress the relative axial sliding between the drill guard 1 and the drilling bush 3. Therefore, the fitting tolerance between the through-hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3 is determined to be tighter than the fitting tolerance between the positioning through-hole 5A and the insertion portion 3B of the drilling bush 3. In this case, the relative rotational movement between the drill guard 1 and the drilling bush 3 will also be suppressed or inhibited according to the degree of the fitting tolerance between the through-hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3.

[0028] The fitting tolerance between the positioning through-hole 5A and the insertion portion 3B of the drilling bush 3 is a clearance fit tolerance such as H7-g6 according to the JIS standard as described above. Therefore, the fitting tolerance between the through-hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3 can be a tolerance corresponding to an intermediate fit or an interference fit according to the usage of the drill guard 1.

[0029] More specifically, when the drill guard 1 is frequently replaced with other drilling bushes 3, the fitting tolerance between the through hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3 can be set to a tolerance corresponding to an interference fit. As a specific example, if the tolerance of the outer diameter D according to the JIS standard in the insertion portion 3B of the drilling bush 3 is g6, the tolerance of the inner diameter according to the JIS standard in the through hole 7A of the connecting portion 7 of the drill guard 1 can be set to H6, G6, etc. Thereby, depending on the fitting tolerance, the drill guard 1 can be removed from the drilling bush 3 by using a wooden hammer or an iron hammer, etc.

[0030] Conversely, when it is not necessary to remove the drill guard 1 from the drilling bush 3, such as when preparing the drill guards 1 in the same number as the drilling bushes 3, a shrink fit such as press fitting can be used. As a specific example, if the tolerance of the outer diameter D according to the JIS standard in the insertion portion 3B of the drilling bush 3 is g6, the tolerance of the inner diameter according to the JIS standard in the through hole 7A of the connecting portion 7 of the drill guard 1 can be set to K6, K7, etc. In this case, the flange 3C of the drilling bush 3 is not necessarily required. That is, the drilling bush 3 can also be a simple cylindrical bush without the flange 3C.

[0031] As described above, there is no upper limit value in the direction of tightening for the fitting tolerance between the through hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3. On the other hand, for the fitting tolerance between the through hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3, there is a lower limit value in the direction of tightening, and it is appropriate to make it tighter than the fitting tolerance between the positioning through hole 5A and the insertion portion 3B of the drilling bush 3.

[0032] The size of the gap between the rotation restraining portion 6B formed by two planes on the inner surface of the cylindrical portion 6 of the drill guard 1 and the two planes 3D for anti-rotation formed on the flange 3C of the drilling bush 3 can be determined according to the fitting tolerance between the through hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3.

[0033] For example, if the fitting tolerance between the through hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3 corresponds to an interference fit, the gap between the rotation restraining portion 6B formed on the inner surface of the cylindrical portion 6 and the flat surface 3D formed on the flange 3C of the drilling bush 3 can be narrowed so as to reliably suppress the relative rotation of the drilling bush 3 with respect to the drill guard 1.

[0034] On the other hand, if the fitting tolerance between the through hole 7A of the connecting portion 7 of the drill guard 1 and the insertion portion 3B of the drilling bush 3 corresponds to a shrink fit, since there is no risk of the drilling bush 3 rotating relative to the drill guard 1, the gap between the rotation restraining portion 6B formed on the inner surface of the cylindrical portion 6 and the flat surface 3D formed on the flange 3C of the drilling bush 3 can be widened so that the flange 3C of the drilling bush 3 and the inner surface of the cylindrical portion 6 do not interfere with each other. Alternatively, since it is not easy to rotate the drilling bush 3 inside the cylindrical portion 6 while inserting the insertion portion 3B of the drilling bush 3 into the through hole 7A of the connecting portion 7 of the drill guard 1, the formation of the rotation restraining portion 6B on the inner surface of the cylindrical portion 6 itself may be omitted, and the inner surface of the cylindrical portion 6 may be a simple cylindrical shape.

[0035] When the insertion portion 3B of the drilling bush 3 is inserted into the positioning through hole 5A of the positioning jig 5 and pushed forward with the drill guard 1 attached, since the outer diameter or the maximum width of the cylindrical portion 6 of the drill guard 1 is larger than the outer diameter D of the insertion portion 3B of the drilling bush 3, the outer surface of the plate-shaped connecting portion 7 of the drill guard 1 comes into contact with the surface around the positioning through hole 5A formed in the positioning jig 5. Thereby, the movement of the drill guard 1 and the drilling bush 3 in the direction toward the workpiece W to be machined is suppressed. In this case, the plate-shaped connecting portion 7 of the drill guard 1 is sandwiched between the flange 3C of the drilling bush 3 and the positioning jig 5.

[0036] Therefore, the entire insertion portion 3B of the drilling bush 3 is not inserted into the positioning through hole 5A formed in the positioning jig 5, and only the portion of the insertion portion 3B of the drilling bush 3 protruding from the drill guard 1 is inserted. That is, the length of the insertion portion 3B of the drilling bush 3 inserted into the positioning through hole 5A formed in the positioning jig 5 is shorter by the thickness T of the disc-shaped connecting portion 7 of the drill guard 1.

[0037] On the other hand, when the workpiece W is an aircraft part, usually, the length of the insertion portion 3B of the drilling bush 3 is determined according to the thickness of the positioning jig 5, that is, the length in the axial direction of the positioning through hole 5A, in the manufacturing specifications. For this reason, it is not appropriate for the protruding length of the insertion portion 3B of the drilling bush 3 from the connecting portion 7 of the drill guard 1 to be shorter than the allowable range of the error defined in the manufacturing specifications.

[0038] Therefore, the thickness T of the plate-shaped connecting portion 7 of the drill guard 1 is set to 1 mm or more and 5 mm or less (1 mm ≤ T ≤ 5 mm), more preferably 1.5 mm or more and 3 mm or less (1.5 mm ≤ T ≤ 3 mm). Thereby, it is possible to secure the protruding length of the insertion portion 3B of the drilling bush 3 from the connecting portion 7 of the drill guard 1 and perform drilling while complying with the manufacturing specifications.

[0039] That is, after inserting the insertion portion 3B of the drilling bush 3 provided with the drill guard 1 into the positioning through hole 5A formed in the positioning jig 5, the drill 2 held by the hand-held tool rotating device held by the operator can be inserted into the through hole 3A of the drilling bush 3 from the open end in the cylindrical portion 6 of the drill guard 1 to drill the workpiece W. Thereby, a perforated product having a through hole or a counterbore processed by the drill 2 can be manufactured.

[0040] As a specific example, in the case of performing an assembly operation of an aircraft structure such as a wing structure, holes for fixing reinforcing members such as girders (spars), ribs, or stringers to the outer plate (panel) with fasteners such as rivets and bolts can be processed. That is, a semi-finished product of an aircraft structure can be manufactured as a perforated product.

[0041] Furthermore, a perforated plate, which is a type of positioning jig 5, is typically specified in the manufacturing specifications to be arranged at a distance of 1.5 times the tool diameter of the drill 2 from the workpiece W. Therefore, the chips generated by the perforation are discharged from the gap between the workpiece W and the perforated plate. Also, in the case of other positioning jigs 5 such as a drilling table, a gap for discharging chips is usually provided, so the chips are discharged from the gap.

[0042] FIG. 5 is a view showing an example in which a part of the broken drill 2 is accommodated inside the cylindrical portion 6 of the drill guard 1 shown in FIG. 1.

[0043] When trying to machine the workpiece W with the drill 2, the drill 2 may break. The drill 2 often breaks at the edge of the entrance of the through-hole 3A formed in the perforation bush 3. When the rotating drill 2 breaks, as illustrated in FIG. 5, the fragments of the broken drill 2 stay inside the cylindrical portion 6 of the drill guard 1 without scattering. As a result, damage to the workpiece W caused by the fragments of the broken drill 2 colliding with the workpiece W can be avoided.

[0044] Furthermore, in the example shown in FIG. 5, since the perforation direction is vertically downward, a part of the broken drill 2 stays on the flange 3C of the perforation bush 3 disposed inside the cylindrical portion 6 of the drill guard 1 due to gravity, but the perforation direction may be other than vertically downward. For example, if the perforation direction is horizontal or a direction close to horizontal, a part of the broken drill 2 will stay on the inner surface disposed on the lower side of the cylindrical portion 6 of the drill guard 1.

[0045] Thus, the cylindrical inner surface of the cylindrical portion 6 of the drill guard 1 becomes a surface for receiving a part of the broken drill 2 when the drill 2 breaks. Therefore, it is important to determine the length L in the axial direction of the cylindrical inner surface of the cylindrical portion 6 to an appropriate length.

[0046] Considering the thickness of the flange 3C of the drilling bush 3, which is standardized according to the length that the fragments of the broken drill 2 can reach and the tool diameter of the drill 2, empirically, it is appropriate to set the axial length L of the cylindrical inner surface in the cylindrical part 6 of the drill guard 1 to be not less than 1 times and not more than 3 times the outer diameter D of the insertion part 3B of the drilling bush 3 (1D ≤ L ≤ 3D).

[0047] This is because when the length L of the inner surface of the cylindrical part 6 is too long, it is necessary to increase the protruding length of the drill 2 from the holder of the tool rotating device in order to avoid interference between the drill guard 1 and the tool rotating device that holds the drill 2, which reduces the rigidity of the drill 2. On the other hand, when the length L of the inner surface of the cylindrical part 6 is too short, there is a risk that a part of the broken drill 2 cannot be retained inside the cylindrical part 6.

[0048] The tool diameter of the drill 2, which is used by being attached to a hand-held tool rotating device and may break, is 10 mm or less. When the workpiece W is an aircraft part, the tool diameter of the drill 2 is often determined in inches, such as φ.1935 inch, and the drilling bush 3 is also standardized for each tool diameter of the drill 2.

[0049] Of course, when the material of the drill 2 is tool steel such as high-speed tool steel (HSS), it may also break when it is made of cemented carbide. Therefore, drills 2 made of tool steel and cemented carbide can be protected by the drill guard 1.

[0050] When the workpiece W is an aircraft part, in addition to metals such as aluminum and titanium, fiber-reinforced plastics (FRP), also known as composite materials such as glass fiber-reinforced plastics (GFRP) and carbon fiber-reinforced plastics (CFRP), can be the target for drilling. Aluminum can be drilled with an HSS drill, but titanium and FRP are difficult-to-machine materials, and carbide drills with low toughness and easy to break are usually used. Therefore, especially when drilling FRP with a carbide drill, the protective effect of the drill guard 1 on the workpiece W is great.

[0051] The materials of the cylindrical portion 6 and the connecting portion 7 of the drill guard 1 can be desired materials such as resin or metal that can ensure the strength necessary to fix the connecting portion 7 to the drilling bush 3 made of metal such as steel and receive the broken drill 2 made of HSS or carbide alloy with the cylindrical portion 6. If the cylindrical portion 6 and the connecting portion 7 are made of resin, it becomes possible to integrally shape the cylindrical portion 6 and the connecting portion 7 as one part with a three-dimensional (3D) printer, and when manufacturing the cylindrical portion 6 and the connecting portion 7 with a 3D printer, the degree of freedom in the shape of the cylindrical portion 6 and the connecting portion 7 can be improved.

[0052] The drill guard 1 as described above is an attachment attached to the drilling bush 3 to accommodate the broken drill 2 so that the workpiece W is not damaged when the drill 2 breaks, when drilling the workpiece W using a hand-held tool rotating device without a feed function in the tool axis direction of the drill 2 and the drilling bush 3. Also, the method for manufacturing the drilled product is such that a high-quality drilled product without scratches is manufactured by drilling the workpiece W using the drilling bush 3 equipped with the drill guard 1.

[0053] (Effect) According to the drill guard 1 and the method for manufacturing the workpiece to be drilled, when the drill 2 breaks, the fragments of the drill 2 can be retained inside the drill guard 1. As a result, damage to the workpiece W can be prevented.

[0054] In addition, the operation of covering the workpiece W with a cover or the like, which has been conventionally performed to prevent damage to the workpiece W, can be made unnecessary. That is, damage to the workpiece W can be prevented only by a simple operation of attaching the drill guard 1 to the drilling bush 3. In other words, instead of comprehensively protecting the entire workpiece W, it is possible to locally protect only the periphery of the portion being drilled by the drill 2 with the drill guard 1.

[0055] Further, not only can the effect of preventing injury to the operator be obtained when the drill 2 breaks, but since the outer diameter of the drill guard 1 is larger than the maximum diameter of the flange 3C of the drilling bush 3, the force required for the operator to hold the drilling bush 3 by hand can be reduced. Incidentally, although the drilling bush 3 may be fixed to the positioning jig 5 by pressing the flange 3C of the drilling bush 3 with a set screw, by attaching the drill guard 1 to the drilling bush 3, it becomes possible to easily hold it by hand, so the operation of fixing the drilling bush 3 with a set screw can be made unnecessary.

[0056] (Modification of the First Embodiment) FIG. 6 is a longitudinal sectional view showing a modification of the drill guard 1 according to the first embodiment of the present invention, FIG. 7 is a front view of the drill guard 1 shown in FIG. 6, FIG. 8 is a top view of the drill guard 1 shown in FIG. 6, and FIG. 9 is a bottom view of the drill guard 1 shown in FIG. 6.

[0057] The shape of the drill guard 1 can be a desired shape. As a specific example, as shown in FIG. 6, a part of the outer surface of the cylindrical portion 6 of the drill guard 1 can be formed into the side surface shape of a truncated cone that is tapered so that the outer diameter of the cylindrical portion 6 gradually decreases toward the tip.

[0058] In this case, when pulling out the insertion portion 3B of the drilling bush 3 together with the drill guard 1 from the positioning through-hole 5A of the positioning jig 5, it becomes possible to apply a force toward the rear end side of the drill guard 1 to the cylindrical portion 6 of the drill guard 1. Therefore, it becomes easy to pull out the drilling bush 3 together with the drill guard 1 from the positioning jig 5.

[0059] Also, as illustrated in FIG. 6, if a part of the inner surface of the cylindrical portion 6 of the drill guard 1 is formed into the side surface shape of a truncated cone tapered so that the inner diameter of the cylindrical portion 6 gradually decreases toward the tip, it becomes possible to easily insert the drilling bush 3 into the cylindrical portion 6 of the drill guard 1 and insert the insertion portion 3B of the drilling bush 3 into the through-hole 7A of the connecting portion 7 of the drill guard 1.

[0060] In addition to the example shown in FIG. 6, the shape of the cylindrical portion 6 can be made asymmetric with respect to the plane including the central axis of the cylindrical portion 6 in order to avoid interference with the workpiece W, or can be formed into the side surface shape of a truncated cone with reverse taper so that the outer diameter of the cylindrical portion 6 gradually increases toward the tip. In the case where the drilling bush 3 has a flange 3C, in order to make the outer shape of the cylindrical portion 6 an asymmetric shape or a reverse taper shape, the inner diameter at the open end of the cylindrical portion 6 needs to be made larger than the maximum diameter of the flange 3C of the drilling bush 3, or the cylindrical portion 6 needs to be divided into a plurality of parts so that the flange 3C of the drilling bush 3 can be disposed inside the cylindrical portion 6 and assembled for use.

[0061] If the outer shape of the cylindrical portion 6 is formed into a reverse taper shape, when inserting the insertion portion 3B of the drilling bush 3 together with the drill guard 1 into the positioning through-hole 5A of the positioning jig 5, it becomes possible to apply a force toward the tip side of the drill guard 1 to the cylindrical portion 6 of the drill guard 1. Therefore, it becomes easy to insert the drilling bush 3 together with the drill guard 1 into the positioning jig 5.

[0062] (Second Embodiment) FIG. 10 is a longitudinal sectional view showing a usage state of a drilling jig 4A including a drill guard 1 and a drilling bush 3 according to a second embodiment of the present invention.

[0063] In the second embodiment shown in FIG. 10, the drilling bush 3 of the drilling jig 4A is different from the drilling bush 3 in the first embodiment in that the length of the insertion portion 3B is made longer than the standard length on the premise of attaching the drill guard 1. Since the other configurations and operations of the drilling bush 3 in the second embodiment are substantially the same as those of the drilling bush 3 in the first embodiment, the same reference numerals are given to the same or corresponding configurations, and the description thereof is omitted.

[0064] As described in the first embodiment, the protruding length of the insertion portion 3B of the drilling bush 3 from the connecting portion 7 of the drill guard 1 is shorter than the length of the connecting portion 7 itself by the thickness T of the connecting portion 7. Therefore, as shown in FIG. 10, the length of the insertion portion 3B of the drilling bush 3 can be made longer than the standard length defined in the specification by the thickness T of the connecting portion 7.

[0065] Then, the protruding length of the insertion portion 3B of the drilling bush 3 from the connecting portion 7 of the drill guard 1 can be made to match the thickness of the positioning jig 5 in which the positioning through hole 5A is formed. In other words, when the insertion portion 3B of the drilling bush 3 is inserted into the through hole 7A of the connecting portion 7, the protruding length of the insertion portion 3B protruding from the connecting portion 7 toward the workpiece W can be designed and determined in advance to match the thickness of the positioning jig 5 in which the positioning through hole 5A is formed.

[0066] Therefore, according to the second embodiment, the error from the manufacturing specification regarding the insertion length of the drilling bush 3 inserted into the positioning jig 5 can be reduced to such an extent that it can be ignored. That is, the insertion portion 3B of the drilling bush 3 can be inserted into the positioning jig 5 by the thickness of the positioning jig 5 defined in the specification.

[0067] (Third Embodiment) FIG. 11 is a longitudinal sectional view showing a usage state of a drilling jig 4B including a drill guard 1 and a drilling bush 3 according to a third embodiment of the present invention, FIG. 12 is a front view of the drilling jig 4B shown in FIG. 11, FIG. 13 is a top view of the drilling jig 4B shown in FIG. 11, and FIG. 14 is a bottom view of the drilling jig 4B shown in FIG. 11.

[0068] The drilling jig 4B in the third embodiment shown in FIGS. 11 to 14 is different from the drilling jig 4A in the second embodiment in that the drill guard 1 and the drilling bush 3 are integrated as a single part. Since other configurations and operations of the drilling jig 4B in the third embodiment are substantially the same as those of the drilling jig 4A in the second embodiment, the same reference numerals are given to the same or corresponding configurations and the description thereof is omitted.

[0069] As shown in FIGS. 11 to 14, the drill guard 1 may be integrated with the drilling bush 3. That is, the material of the drill guard 1 is made the same as the material of the drilling bush 3, and a drilling bush 3 having the drill guard 1 as one part can be manufactured by cutting out from a metal material such as steel.

[0070] In this case, there is no need for the portion of the drilling bush 3 to have a flange 3C. In other words, the connecting portion 7 of the drill guard 1 functions like the flange 3C. Therefore, the length L in the axial direction of the inner surface of the cylindrical portion 6 of the drill guard 1 can be shortened by the thickness of the flange 3C. Further, the length of the insertion portion 3B of the drilling bush 3 is appropriately designed and determined in accordance with the thickness of the positioning jig 5.

[0071] According to the above third embodiment, the assembly work for attaching the drill guard 1 to the drilling bush 3 can be made unnecessary. Therefore, particularly when mass-producing the drilling jig 4B including the drill guard 1 and the drilling bush 3 or when it is difficult to prepare a 3D printer, the manufacturing cost of the drilling jig 4B may be reduced. Further, since no resin is used, it is possible to prevent deterioration of the quality of the drill guard 1 and to prevent the generation of waste leading to environmental destruction.

[0072] (Other Embodiments) As described above, specific embodiments have been described, but the described embodiments are merely examples and do not limit the scope of the invention. The novel methods and apparatuses described herein can be embodied in various other manners. Also, in the manners of the methods and apparatuses described herein, various omissions, substitutions, and changes can be made without departing from the gist of the invention. The appended claims and their equivalents include such various manners and modifications as being included in the scope and gist of the invention.

[0073] For example, in each of the above-described embodiments, a perforated plate and a perforated base were mentioned as examples of the positioning jig 5. However, a perforation guide that is used by inserting a perforation bush so as to be able to perforate with a drill that holds a composite curved surface having a plurality of curvatures, as disclosed in the application documents of Japanese Patent Application No. 2023-077529, with a hand-held tool rotating device, also corresponds to an example of the positioning jig 5.

Explanation of Reference Numerals

[0074] 1 Drill guard 2 Drill 3 Perforation bush 3A Through hole 3B Insertion part 3C Flange 3D Plane 4, 4A, 4B Perforation jig 5 Positioning jig 5A Through hole for positioning 6 Cylindrical part 6A Holding part 6B Rotation suppression part 7 Connecting part 7A Through hole D Outer diameter of the insertion part of the perforation bush L Length of the cylindrical part of the drill guard T Thickness of the connecting part of the drill guard W Workpiece

Claims

1. A drill guard that has a through-hole for inserting a drill, is used by being attached to a positioning drill bush that is inserted into a through-hole for positioning or is integrated with the drill bush, and has a cylindrical portion having an outer diameter or maximum width larger than the outer diameter of the insertion portion of the drill bush for insertion into the through-hole for positioning, and a connecting portion for connecting one end of the cylindrical portion to the insertion portion of the drill bush, and by making the other end of the cylindrical portion an open end, the drill can be inserted into the through-hole of the drill bush from the open end side, and when the drill breaks, the fragments of the broken drill stay inside the cylindrical portion without scattering. A drill guard.

2. A drill guard that is used by being attached to a drill bush having a flange with an outer diameter larger than the outer diameter of the insertion portion, and the connecting portion has a through-hole for inserting the insertion portion with the flange of the drill bush disposed inside the cylindrical portion, The drill guard according to claim 1, wherein the fitting tolerance between the through-hole of the connecting portion and the insertion portion of the drill bush is made tighter than the fitting tolerance between the through-hole for positioning and the insertion portion of the drill bush.

3. The drill guard according to claim 1, wherein the length of the cylindrical inner surface of the cylindrical portion in the axial direction is 1 to 3 times the outer diameter of the insertion portion of the drill bush.

4. A method for manufacturing a perforated product, wherein the insertion portion of the drill bush provided with the drill guard according to any one of claims 1 to 3 is inserted into the through-hole for positioning, and the drill is inserted into the through-hole of the drill bush to perforate a workpiece to manufacture the perforated product.

5. A method for manufacturing a perforated product, wherein the insertion portion of the drill bush provided with the drill guard according to claim 2 is inserted into the through-hole for positioning, and the drill is inserted into the through-hole of the drill bush to perforate a workpiece to manufacture the perforated product, and a method for manufacturing a perforated product, wherein the protruding length of the insertion portion protruding from the connecting portion toward the workpiece side when the insertion portion of the drill bush is inserted into the through-hole of the connecting portion is determined in accordance with the thickness of a positioning jig in which the through-hole for positioning is formed.

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