JP4272608B2 - Unscrewing bit - Google Patents

Description

  The present invention relates to a screw removal bit for removing a screw in which a screw hole locking screw hole is crushed in a screwed state.

  Conventionally, as a tool used to remove a screw whose locking hole for screwdriver on the screw head is crushed, a tapered left-hand screw that gradually decreases in diameter toward the distal end is used at the distal end of the handle. There is a screw removal bit provided with an extraction screw part.

This unscrewing bit can be used by attaching it to a rotary tool such as an electric screwdriver or electric drill. A pilot hole is drilled in the center of the screw head where the locking hole is crushed, and the extraction screw is inserted into this pilot hole. With the tip of the part inserted, the extraction screw part is screwed into the pilot hole by rotating the screw removal bit in the direction opposite to the thread cutting direction while pressing the rotary tool from above. Since this extraction screw part is tapered, if it is screwed into the pilot hole, the contact area between the surface of the extraction screw part and the inner surface of the pilot hole will increase, increasing the frictional resistance, and the screw will serve as the screw removal bit. To turn around. In this case, the screw rotates in the loosening direction, so that it can be removed from the screwed member.
No. 2002-3397 (Pages 1 and 2 and FIG. 1)

  However, since the above-described screw unscrewing bit needs to be drilled with a pilot hole, the work is troublesome, and a drill for the pilot hole is also required separately.

  The present invention has been made in view of these problems, and an object thereof is to provide a convenient screw removal bit capable of removing a screw whose locking hole for screwdriver is crushed by a simpler operation.

  The screw removal bit according to claim 1 is a screw removal bit for removing a screw in which a locking hole for screwdriver in the screw head is crushed, and extends from the proximal end side to the distal end side at the distal end portion of the handle. Provided with a screw extraction part having a tapered tip having a gradually reduced diameter at the tip, and the length of the handle from the tip of the tip to the proximal side on the outer peripheral surface of the screw removal part. A groove extending in the vertical direction is formed, and an intersecting line between the inner surface of the groove and the outer peripheral surface of the screw extraction portion is a cutting blade that can be cut when rotating in the direction opposite to the thread cutting direction of the screw. In addition, when the screw extraction part is cut to a predetermined depth in the central part of the screw head, a notch part is provided for engaging the screw by being hooked on the inner surface part of the locking hole. .

  According to the screwing bit of claim 1, the tip of the tip is aligned with the center of the screw head where the locking hole is crushed, and the screw is held while pressing the screwing bit from above. When the screw extraction portion is cut into the screw head while cutting with the cutting blade, the cutout portion is moved into the predetermined direction when the cutting depth reaches a predetermined depth. The screw can be rotated around the inner surface of the locking hole. That is, the screw can be rotated in the loosening direction. Therefore, the screw can be extracted without drilling a pilot hole in the screw head.

The screw removal bit according to claim 2, wherein the outer peripheral surface of at least the tip of the screw extraction portion from the tip portion to the cutout portion has a tapered shape in which both sides are curved inward in a longitudinal section. It is characterized by forming.

  According to the screw removal bit of claim 2, when the screw extraction portion is cut into the screw head, cutting can be performed without increasing the diameter of the cut hole until the cut depth reaches the cutout portion. As a result, the notch can be easily caught on the inner surface of the locking hole.

  The threading bit according to claim 3 forms a groove so that an intersecting line different from the intersecting line forming the cutting edge is inclined upward in a direction opposite to a cutting direction of the cutting blade. It is characterized by that.

  According to the screwing bit of claim 3, when removing the screw extraction part of the screwing bit from the screw head, the screwing bit is set in a direction opposite to the rotational direction in which the cutting blade can be cut. When rotated, the inner surface of the groove constituting the another intersection line is inclined in the same direction as the screw loosening in the rotation direction, and therefore can be easily removed from the screw head.

  The screwing bit of the present invention made by the above means does not need to make a pilot hole in the screw, so that the work can be saved and the work can be done quickly and quickly. . Moreover, since a drill for a pilot hole is not required, it is economical and easy to handle.

  An embodiment of a screwing bit according to the present invention will be described based on FIGS. 1 and 2 for a right-hand thread. FIG. 1A is a side view of the screw removal bit 1, FIG. 1B is a bottom view of the screw removal bit, that is, a view seen from the tip side, and FIG. 1C is a view of the screw removal bit. It is the perspective view of a front-end | tip part, and the figure which expanded partially.

  The screw removal bit 1 is formed using a special alloy, and a screw removal part 3 is provided at the tip of a handle 2 formed in a hexagonal column shape having a regular hexagonal cross section.

  The base end corner of the handle 2 is chamfered, and a groove having a shape in which the longitudinal section is recessed in an arc toward the inside is formed on the outer peripheral surface at a position separated from the base end surface by a predetermined distance. An annular locking portion 4 is provided in the circumferential direction. Thereby, the screw removal bit 1 can be mounted on the rotary tool.

  On the other hand, the screw extraction part 3 has a circular cross-sectional shape, and after the handle 2 is reduced in diameter and formed into a tapered shape so that both sides of the vertical cross-section are gently curved inwardly, In the vertical cross section, the tapered portion is tapered so that both sides are gently curved inward, and then gradually reduced in diameter to provide a pointed portion 5 having a tapered outer peripheral surface with a steep slope.

  Further, a groove 6 having an L-shaped cross section extending in the length direction of the handle 2 is formed on the outer peripheral surface of the screw extraction portion 3 from the distal end of the tip portion 5 toward the proximal end side. The inner surface of the groove 6 is formed such that the left surface 6a as viewed from the side includes a shaft x passing through the center of the cross section of the handle 2 and extending in the same direction as the length direction of the handle 2. It has become. The right surface 6b is provided at a right angle to the right surface 6a and includes the tip center of the tip 5 and is included in a surface inclined toward the cutting edge 7 with respect to the length direction of the handle 2. Is formed. Therefore, the line of intersection between the right surface 6a and the outer peripheral surface of the screw extraction portion 3 is inclined upward as viewed from the side.

The crossing line between the left surface 6a of the groove 6 provided in this way and the outer peripheral surface of the screw extraction portion 3 is cut when the screw extraction bit 1 is rotated counterclockwise about the axis x. It is a blade 7.

  The cutting blade 7 has a notch portion 8 that is hooked on the inner surface of the locking hole when the screw extraction portion 3 is cut into the center of the screw head to a predetermined depth, and rotates the screw. Are provided so as to be recessed in an arc shape. By providing the notch portion 8 in this way, the cutting edge 7 is in a state where the edge is missing.

  By providing this notch 8, an inclined surface 9 is formed on the cutting edge 7. The inclined surface 9 has a circular cross-sectional shape, and is inclined slightly to the left with respect to the left surface 6a.

  Next, a case where a wood screw is extracted using the screw removal bit 1 will be described with reference to FIG. FIG. 2A shows a state in which a right-handed wood screw is screwed into member A, and a locking hole (cross hole) for locking the tip of a screwdriver on the screw head is crushed. (B) is explanatory drawing at the time of using a screwing bit attached to a rotary tool, (c) is the elements on larger scale of the B section in (b).

  As shown in FIG. 2A, the wood screw 30 is screwed into the member A, and the cross hole 32 of the screw head 31 is crushed so that it cannot be removed with a Phillips screwdriver.

  First, the handle 2 of the screw removal bit 1 is inserted into the chuck 20a of the rotary tool 20 such as an electric screwdriver or an electric drill, and the locking portion 4 is locked in the chuck 20a to rotate the screw removal bit 1. Attach to the tool 20. Thus, the unscrewing bit 1 attached to the chuck 20a is prevented from falling off or idling due to the locking portion 4.

  As shown in FIG. 2B, the tip of the tip 5 of the screw removal bit 1 is made to coincide with the center of the screw head 31 of the wood screw 30, and the direction of the screw removal bit 1 is set to the wood. The rotary tool 20 is held in a state in which the direction of the screw 30 is matched. Then, the rotary tool 20 is driven to press the rotary tool 20 from above while rotating the screw removal bit 1 counterclockwise, the tip 5 of the screw removal bit 1 is pressed against the screw head 31, and the screw removal portion Cut with 3 cutting blades 7.

  If it does so, as shown in FIG.2 (c), when the cutting depth reaches the notch part 8 of the cutting blade 7, it will not cut further. This is because the cut-out portion 8 is provided so that the blade of the cut-off blade 7 is cut off, so that the inclined surface 9 of the cut-out portion 8 is hooked on the inner surface of the cross hole 32. Become.

  At this time, the outer peripheral surface of the screw extraction portion 3 is tapered from the tip of the tip 5 to the notch 8 so that both sides of the longitudinal section are curved inwardly. Until the notch 8 is reached, it can be cut without enlarging the notch hole so that the inclined surface 9 of the notch 8 is easily caught on the inner surface of the cross hole 32.

  Then, when the screwing bit 1 is continuously rotated, the wood screw 30 is rotated with the screwing bit 1 in a state where the screw head 31 is hooked on the cutting blade 7 and is rotated counterclockwise, that is, loosened. Rotate to. Thus, the wood screw 30 in which the cross hole 32 is crushed can be easily extracted from the member A.

After removing the wood screw 30 from the member A, when removing the screw extraction portion 3 from the screw head 31 of the wood screw 30, the screw extraction portion 3 has a right surface 6b on the outer peripheral surface thereof ascending to the left when viewed from the side, That is, since it is inclined in the direction of the left screw, when the screw removal bit 1 is rotated clockwise with respect to the wood screw 30,
It can be quickly and easily removed from the wood screw 30.

  Three types of screw removal bits 1 having different diameters of the screw extraction part 3 are prepared, and can be selectively used according to the size of the diameter of the wood screw.

  In the present embodiment, the notch 8 is provided only in a portion located in the middle portion of the cutting edge 7, but the present invention is not limited to this. Notches may be provided on all sides.

  In this embodiment, one groove 6 is formed in the screw extraction part 3 and only one cutting blade 7 is provided. However, a plurality of cutting blades may be provided by forming a plurality of grooves. it can.

  Furthermore, the handle 2 is formed in the shape of a hexagonal column, but is not limited to this shape, and may be formed in the shape of, for example, a square column. In this embodiment, the screw removal bit 1 is attached to a rotary tool and used, but it may be attached to a fixture such as a tap handle and manually removed. In this case, since a rotary tool is not required, it is effective when a power source or the like is not nearby, and the handle can be simplified because a locking portion for the rotary tool is not required on the handle.

(A) is one side view of a screw removal bit. (B) is a bottom view of the screw removal bit. (C) is the elements on larger scale which show the screw extraction part of the bit for screw removal. (A) is explanatory drawing which shows the state which the cross hole of the wood screw screwed in the member is crushed. (B) is explanatory drawing which shows the use condition of the bit for screw removal, and represents a part of screw head of the wood screw with the cross section. (C) is the elements on larger scale of the B section in (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screw removal bit 2 Handle 3 Screw extraction part 4 Locking part 5 Pointed part 6 Groove 6a Left side 6b Right side 7 Cutting blade 8 Notch 9 Inclined surface

Claims (3)

  A screw removal bit for removing a screw whose locking hole for screwdriver on the screw head is crushed, and has a tapered shape that gradually decreases in diameter from the proximal side to the distal side at the distal end of the handle And a groove extending in the length direction of the handle from the tip of the tip to the base end side is provided on the outer peripheral surface of the screw extractor. Formed, the intersecting line between the inner surface of the groove and the outer peripheral surface of the screw extraction part is a cutting blade that can be cut when rotating in the direction opposite to the thread cutting direction of the screw. When the screw extraction part is cut to the center of the screw head to a predetermined depth, a notch part is provided for engaging the screw by being hooked on the inner surface part of the locking hole. Unscrewing bit.   The outer peripheral surface of at least the tip of the tip of the screw extraction part to the notch is formed in a tapered shape in which both sides are curved inward in a longitudinal section. Item 2. A screw removal bit according to Item 1.   The groove is formed so that an intersecting line different from the intersecting line serving as the cutting edge is inclined upward in a direction opposite to a rotation direction in which the cutting blade can be cut. Item 3. An unscrewing bit according to item 1 or 2.

Images