Chuck mechanism for power tool

Abstract

To provide a chuck mechanism of a power tool capable of easily attaching and detaching a tip tool.SOLUTION: The chucking mechanism 20 is mounted on a chucking shaft 21 having an insertion hole 21a into which the end bit can be inserted so as to reciprocate along the outer peripheral surface of the chucking shaft. And a sleeve locking means 25 for fixing the sleeve at a predetermined position when the sleeve is retracted against the urging of the spring, wherein when the tip tool is inserted into the chuck shaft with the sleeve fixed by the sleeve locking means, the tip tool abuts on the sleeve locking means and moves the sleeve locking means to release the fixation of the sleeve, and the sleeve advances by the urging of the spring. And a tool lock means 23 for fixing the tip tool to the chuck shaft in the advanced state of the sleeve.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] The above problem can be solved by a chuck mechanism for an electric tool to which a tool bit can be attached or detached, the chuck mechanism comprising: 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; sleeve lock means for fixing the sleeve in a predetermined position when the sleeve is moved back against the bias of the spring; and when the tool bit is inserted into the chuck shaft with the sleeve fixed by the sleeve lock means, the tool bit comes into contact with the sleeve lock means and, by moving the sleeve lock means, the fixation of the sleeve is released and the sleeve moves forward due to the bias of the spring, and tool lock means for fixing the tool bit to the chuck shaft when the sleeve is advanced.

[0007] It is preferable that the sleeve lock means has an engaging portion which engages with a locking portion formed on the inner surface of the sleeve to fix the sleeve at a predetermined position, and that the sleeve lock means is configured so that it disengages from the locking portion of the sleeve when pushed and moved by the tool tip.

[0008] The power tool is preferably for medical use, used in surgical operations for screwing medical screws into bones. [Effects of the Invention]

[0009] 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]

[0010] [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

[0011] 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.

[0012] The driver bit 2 has an annular engagement groove 2a on its outer circumferential surface, which is configured to fit with a steel ball 23 of a chuck mechanism 20, the details of which will be described later.

[0013] 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).

[0014] The chuck mechanism 20 is composed of a chuck shaft 21 having an 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 first coil spring 3.

[0015] At the tip of the chuck shaft 21, storage holes 21b are provided at two locations as horizontal holes in the direction intersecting with the insertion hole 21a, and steel balls 23 serving as tool locking means are stored in these storage holes 21b.

[0016] As shown in FIG. 1, when the sleeve 22 is retracted against the bias of the first coil 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 the sleeve lock means 25.

[0017] The sleeve lock means 25 has a comma-shaped configuration with an engaging portion 25a at one end, and is disposed inside the chuck shaft 21 on a rear extension of the insertion hole 21a. The sleeve lock means 25 is biased forward (toward the tip end of the driver bit 2) by a second coil spring via the pin 5. Meanwhile, an annular groove 22a is formed on the inner peripheral surface of the sleeve 22, and the sleeve lock means 25 is configured to fix the sleeve 22 at a predetermined position by engaging the engaging portion 25a with the annular groove 22a.

[0018] Furthermore, at the tip of the sleeve 22, a small space is formed between its inner peripheral surface and the outer peripheral surface of the chuck shaft 21, and this space functions as a clearance 22b for the steel ball 23. Therefore, in the state shown in Fig. 1, the steel ball 23 is exposed outward from the storage hole 21b (toward the outer peripheral side of the sleeve 22) but is not exposed inward (toward the insertion hole 21a of the chuck shaft 21), and the driver bit 2 is ready to be inserted into the insertion hole 21a of the chuck shaft 21.

[0019] 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 sleeve lock means 25, causing the sleeve lock means 25 to move backward against the bias of the second coil spring 4. Accordingly, the sleeve lock means 25 is disengaged from the sleeve 22, and the sleeve 22 moves forward due to the bias of the first coil spring 3. At this time, the steel ball 23 is pushed by the inner circumferential surface of the sleeve 22 and moves inward (toward the insertion hole 21a of the chuck shaft 21) and engages with the engagement groove of the driver bit 2, thereby attaching the driver bit 2 to the chuck mechanism 20.

[0020] 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.

[0021] 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.

[0022] 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]

[0023] 1. Electric screwdriver (power tool) 2 Driver Bits (Tools) 2a Engagement groove 3 First coil spring 4 Second coil spring 5-pin 10 Main body 20 Chuck mechanism 21 Chuck axis 21a Insertion hole 21b Storage hole (horizontal hole) 22 Sleeve 22a Annular groove 22b Relief 23 Steel ball (tool locking means) 25 Sleeve lock means 25a Engagement 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 bit is inserted into the chuck shaft with the sleeve fixed by the sleeve locking means, the tool bit comes into contact with the sleeve locking means, and by moving the sleeve locking means, the sleeve is released from the fixed state and moves forward by the bias of a spring, and for locking the tool to the chuck shaft when the sleeve is advanced; A chuck mechanism for a power tool, comprising:

2. 2. The chuck mechanism for a power tool according to claim 1, wherein the sleeve lock means has an engaging portion which engages with a locking portion formed on the inner surface of the sleeve to fix the sleeve in a predetermined position, and the sleeve lock means is configured to be pushed and moved by the tool bit so that it disengages from the locking portion of the sleeve.

3. 3. The chuck mechanism for 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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