Chuck mechanism for electric power tool

Abstract

To provide a chuck mechanism for an electric power tool that is able to easily attach and detach a tip tool.SOLUTION: A chuck mechanism for an electric power tool includes: a chuck shaft 21 having an insertion hole through which a driver bit 2 can be inserted; a sleeve 22 that is mounted so as to be able to reciprocate along an outer peripheral surface of the chuck shaft 21 and is constantly biased forward by a spring 3; an opening / closing claw 25 that fixes the sleeve at a predetermined position when the sleeve is retracted against the bias of the spring; and tool locking means that, when the driver bit 2 is inserted into the chuck shaft while the sleeve is kept fixed by the opening / closing claw, the driver bit operates the opening / closing claw to release the fixation of the sleeve so that the sleeve is moved forward by the bias of the spring, and the driver bit is fixed to the chuck shaft while the sleeve is kept moved forward.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a chuck mechanism for attaching a tool tip to a handheld power tool, and more particularly to a chuck mechanism for a power tool used in a surgical operation. [Background technology]

[0002] For example, an electric screwdriver for medical use is shown in Patent Document 1. Many electric screwdrivers for medical use employ one of the following chuck mechanisms for attaching a driver bit: a one-touch sleeve, a drill chuck, or a keyless chuck. A one-touch sleeve is configured so that the lock ring is pulled toward you, the driver bit is inserted, and when you release the lock ring in this state, the lock ring returns to its original position due to the force of a spring, thereby securing the driver bit. A drill chuck is configured so that a dedicated chuck key is used to tighten and secure the driver bit in the chuck. A keyless chuck is configured so that the chuck is opened and closed by rotating a cylindrical sleeve, and the driver bit is attached thereto. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 60-138670 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional medical electric screwdrivers have complex chuck mechanisms with many parts, making them large and difficult to use in confined spaces such as surgery. Also, the user must manually operate the chuck when attaching the screwdriver bit, which poses hygiene management issues in medical settings.

[0005] The present invention has been made in view of the above problems, and has an object to provide a chuck mechanism for a power tool that allows a driver bit to be easily attached. [Means for solving the problem]

[0006] A chuck mechanism for an electric tool to which a tool bit can be attached and detached comprises: a chuck shaft having an insertion hole through which the tool bit can be inserted; a sleeve mounted so as to be reciprocatable along the outer peripheral surface of the chuck shaft and constantly biased by a spring toward the tip of the tool bit; a sleeve lock means for fixing the sleeve in a predetermined position when the sleeve is moved back against the bias of the spring; and a tool lock means for fixing the sleeve in a predetermined position when the tool bit is inserted into the chuck shaft with the sleeve fixed by the sleeve lock means, which operates the sleeve lock means to release the sleeve so that the sleeve moves forward under the bias of the spring, and which fixes the tool bit to the chuck shaft when the sleeve is advanced.

[0007] It is preferable that the sleeve locking means is a pair of opening and closing claws interposed between the sleeve and the chuck shaft, with a barbed portion formed at the tip of the opening and closing claws and a locking portion formed on the inner surface of the sleeve, and that the barbed portion engages with the locking portion to fix the sleeve at a predetermined position.

[0008] Preferably, the tool locking means is a steel ball that is housed in a horizontal hole drilled in the chuck shaft, while an annular engagement groove is formed on the outer circumferential surface of the tool bit, and when the tool bit is inserted into the chuck shaft and the engagement groove reaches the position of the steel ball, the steel ball fits into the engagement groove.

[0009] The power tool is preferably for medical use, used in surgical operations for screwing medical screws into bones. [Effects of the Invention]

[0010] According to the chuck mechanism of the power tool of the present invention, the user can easily attach the driver bit by simply inserting it, without having to operate the chuck mechanism. [Brief explanation of the drawings]

[0011] [Figure 1] 2 is an enlarged cross-sectional view of a main part of a chuck mechanism of the power tool according to the present invention. FIG. [Figure 2] 4 is an enlarged cross-sectional view of a main part showing an operating state of the chuck mechanism of the power tool according to the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In Figures 1 and 2, reference numeral 1 denotes an electric screwdriver as an example of a power tool. This electric screwdriver 1 comprises a main body 10 and a chuck mechanism 20 disposed at the tip of the main body 10, to which a driver bit 2, which is a tip tool, can be attached. Note that the tip tool may be a tap for machining a female thread, instead of the driver bit 2.

[0013] The driver bit 2 has an annular engagement groove 2a on its outer circumferential surface, and is configured to fit with a first steel ball 23 of a chuck mechanism 20, the details of which will be described later.

[0014] A motor (not shown) driven by an external power source is built into the main body 10. This motor is configured to be driven by a user operating a switch (not shown) provided on the main body 10, and an output shaft (not shown) of the motor is connected to a chuck shaft 21 of a chuck mechanism 20, the details of which will be described later, via a reducer (not shown).

[0015] The chuck mechanism 20 is composed of a chuck shaft 21 having a bottomed insertion hole 21a through which the driver bit 2 can be inserted, and a sleeve 22 that is mounted so as to be able to move back and forth along the outer peripheral surface of the chuck shaft 21 and is constantly biased forward (toward the tip of the driver bit 2) by a spring 3.

[0016] At the tip of the chuck shaft 21, first storage holes 21b are provided in two locations as horizontal holes in the direction intersecting with the insertion hole 21a, and these storage holes 21b store first steel balls 23, which are tool locking means.

[0017] Further, in the chuck shaft 21, second storage holes 21c are provided at two locations as horizontal holes in the direction intersecting with the insertion hole 21a near the bottom of the insertion hole 21a, and second steel balls 24 are stored in the second storage holes 21c. The second steel balls 24 are used to operate the open / closed state of a pair of opening / closing claws 25, the details of which will be described later.

[0018] 1, when the sleeve 22 is retracted against the bias of the spring 3 and the driver bit 2 is not attached to the chuck mechanism 20, the sleeve 22 is fixed in a predetermined position by a pair of opening / closing claws 25, which are an example of a sleeve locking means. The opening / closing claws 25 are interposed between the chuck shaft 21 and the sleeve 22, and have a barbed portion 25a at their tip. Meanwhile, a locking portion 22a that protrudes inward is formed on the inner peripheral surface of the sleeve 22, and the barbed portion 25a engages with the locking portion 22a to fix the sleeve 22 in a predetermined position.

[0019] 1, at the tip of the sleeve 22, a small space is formed between the inner peripheral surface of the sleeve 22 and the outer peripheral surface of the chuck shaft 21, and this space functions as a clearance 22b for the first steel ball 23. Therefore, in the state shown in FIG. 1, the first steel ball 23 is exposed outward (toward the sleeve 22) from the first storage hole 21b, but is not exposed inward (toward the insertion hole 21a of the chuck shaft 21).

[0020] 1, the second steel ball 24 is not exposed outward (toward the sleeve 22) from the accommodation hole 21c, but is exposed inward (toward the insertion hole 21a of the chuck shaft 21). The opening / closing claws 25 are disposed outward from the second steel ball 24, and are configured so that the opening / closing claws 25 are opened or closed by the second steel ball 24 moving outward or inward. Therefore, in the state shown in FIG. 1, the second steel ball 24 is not pressing or operating the opening / closing claws 25, so the tip of the opening / closing claw 25 is in an open state, and the return portion 25a is engaged with the locking portion 22a on the inner circumferential surface of the sleeve 22.

[0021] As shown in FIG. 2, when the driver bit 2 is attached to the chuck mechanism 20 in the state shown in FIG. 1, the rear end of the driver bit 2 inserted into the insertion hole 21a of the chuck shaft 21 abuts against the second steel ball 24, moving the second steel ball 24 outward, and the opening / closing claws 25 are pushed by the second steel ball 24 to close their tips. This disengages the return portion 25a of the opening / closing claws 25 from the locking portion 22a of the sleeve 22, and the sleeve 22 moves forward due to the bias of the spring 3. Then, the first steel ball 23 is pushed by the inner circumferential surface of the sleeve 22 and accommodated in the accommodation hole 21b, and is exposed inward (toward the insertion hole 21a of the chuck shaft 21). At this time, the first steel ball 23 and the engagement groove 2a of the driver bit 2 fit together, and the driver bit 2 is attached to the chuck mechanism 20. To remove the driver bit 2 from the chuck mechanism 20, the user manually moves the sleeve 22 backward against the bias of the spring 3 to return it to the state shown in FIG.

[0022] According to the chuck mechanism 20 of the electric screwdriver 1, the user can easily attach the driver bit 2 by simply inserting it, without having to operate the chuck mechanism 20. In addition, the number of parts constituting the chuck mechanism 20 is small, allowing for miniaturization.

[0023] In particular, the chuck mechanism 20 of the electric screwdriver 1 is hygienic as the user only needs to touch the chuck mechanism 20 a small number of times, making it suitable for medical use in surgical operations to screw medical screws into fractures.

[0024] The chuck mechanism 20 of the electric screwdriver 1 can be modified in various ways without departing from the spirit of the present invention. [Explanation of symbols]

[0025] 1. Electric screwdriver (power tool) 2 Driver Bits (Tools) 2a Engagement groove 3 Coil springs 10 Main body 20 Chuck mechanism 21 Chuck axis 21a Insertion hole 21b First storage hole (horizontal hole) 21c Second storage hole (horizontal hole) 22 Sleeve 22a Locking part 22b Relief 23 First steel ball (tool locking means) 24 Second Steel Ball 25 Opening and closing claw (sleeve lock means) 25a Return part

Claims

1. In a chuck mechanism of an electric tool to which a tip tool can be attached or detached, The chuck mechanism includes: a chuck shaft having an insertion hole through which the tool bit can be inserted; a sleeve mounted on the chuck shaft so as to be reciprocatable along an outer peripheral surface of the chuck shaft and constantly biased toward the tip end of the tool bit by a spring; a sleeve locking means for fixing the sleeve at a predetermined position when the sleeve is retracted against the bias of the spring; a tool locking means for locking the tool to the chuck shaft when the tool is inserted into the chuck shaft with the sleeve fixed by the sleeve locking means, and the tool operates the sleeve locking means to release the fixation of the sleeve and move the sleeve forward by the bias of a spring, and for locking the tool to the chuck shaft when the sleeve is forward; A chuck mechanism for a power tool, comprising:

2. 2. The chuck mechanism of a power tool according to claim 1, wherein the sleeve locking means is a pair of opening and closing claws interposed between the sleeve and the chuck shaft, the opening and closing claws having barbed portions at their tips and locking portions formed on the inner peripheral surface of the sleeve, and the barbed portions engaging with the locking portions to fix the sleeve in a predetermined position.

3. 3. The chuck mechanism for a power tool according to claim 1 or 2, wherein the tool locking means is a steel ball, the steel ball being housed in a horizontal hole drilled in the chuck shank, while an annular engagement groove is formed on the outer circumferential surface of the tool bit, and when the tool bit is inserted into the chuck shank and the engagement groove reaches the position of the steel ball, the steel ball fits into the engagement groove.

4. 2. The chuck mechanism of a power tool according to claim 1, wherein the power tool is for medical use, used in a surgical operation for screwing a medical screw into a bone.

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