JPH0741553B2 - Impact tool - Google Patents

Description

TECHNICAL FIELD The present invention relates to an impact tool having a structure that can be easily disassembled and assembled and that is sufficiently resistant to impact.

“Prior Art” Impact tools are desired to be small and lightweight in consideration of portability, and yet to withstand severe impacts.

For this reason, efforts have been made to reduce the size and design impact resistance.

An example of such a conventional impact tool will be described with reference to the drawings, and FIG. 3 is a longitudinal sectional view of an essential part showing a bit holder portion of the impact tool.

In FIG. 3, the impact tool includes a bit lock body 2 and a lock ring 3 of the lock body 2 in a bit attaching / detaching portion 1 to which a bit (not shown) is attached.

The bit attaching / detaching portion 1 is configured to be struck in the rotating and axial directions by an electric motor (not shown) via the driving portion 4, and these configurations are coaxially combined with the bit attaching / detaching portion 1. It is assembled by the cap 5 at the end.

With such a configuration, since the bit holder portion can be configured with the shaft center, an impact tool that can be easily processed and assembled can be configured.

[Problems to be Solved by the Invention] However, in such a configuration, after the lock body 2 and the lock ring 3 are assembled with the bit attaching / detaching portion 1 as an axis, the end portion is closed by the cap 5. is doing.

Therefore, it is necessary to lock the cap 5 so as not to loosen it, and this locking is not easy.

That is, due to the nature of the impact tool, violent vibration is generated in the bit attaching / detaching portion 1, and this vibration has no effect in the easy locking.

However, a strong lock causes a problem of disassembly, and a complicated structure causes a problem of making the whole large.

That is, if the cap 5 is locked with an adhesive or the like, the structure is simple but disassembly becomes difficult, and if a structure such as a lock pin or a double nut is provided, the structure becomes complicated, Reliability was a problem.

In particular, the portion of the cap 5 close to the bit may come into direct contact with the processed material with violent vibration, and impact resistance is required.

Further, in this kind of impact tool, it is preferable that the axial dimension of the bit is short in terms of work, and it is desired that the structure of the cap 5 is simple and small.

"Problems to be Solved by the Invention" The present invention forms a screw on the outer periphery of the end of a bit holder,
A bowl-shaped cap that is screwed onto the end of the screw is provided, and a sliding contact portion that is formed by a tapered surface and is pressed against the bit holder side is formed on this cap, and the axes of the sliding contact portions are eccentric to each other. The problem is solved by assembling the bit holder with this cap.

[Operation] Since the bowl-shaped cap and the bit holder side are pressed against each other while being eccentric to each other, the contact friction changes due to the eccentricity in the rotational direction.

For this reason, if it is tightly tightened, it will not be loosened and locked at the portion where the friction increases.

In addition, since the cap is formed in a bowl shape, it is rigid and slightly deformable in the radial direction, which is flexible and convenient in the rotation direction.

[Embodiment] The present invention as described above will be explained based on the embodiment shown in the drawings. FIG. 1 is a longitudinal sectional view of a main part of an impact tool according to an embodiment of the present invention, and FIG. FIG. 4 is an enlarged vertical cross-sectional view of the relevant part.

In FIG. 1, the impact tool is configured so that a bit (not shown) can be attached to and detached from a bit attaching / detaching portion 6 formed in a substantially cylindrical shape.

The bit attaching / detaching portion 6 is provided with a lock body 7 that is movable in the radial direction so as to hold the bit to be fitted, and the lock ring 8 regulates the movement from the outside.

Further, the lock ring 8 is configured such that the lock body 7 is opened in the radial direction by moving in the axial direction, and is operated when attaching or detaching the bit.

Since the bit is configured to rotate, the bit attaching / detaching portion 6 is connected to the driving portion 9 and is configured to be driven by an electric motor (not shown) or the like.

The lock ring 8 is urged toward the bit side by the spring 10, and by moving the lock ring 8 in the axial direction against the urging force of the spring 10, the space 11 is moved to the lock body 7. It is configured to allow radial movement.

Furthermore, a cap 12 is screwed onto the tip of the bit attaching / detaching part 6.

The cap 12 regulates the lock ring 8 in the axial direction, and has a function of assembling and holding the lock ring 8, the spring, the locking body 7, and the like on the bit attaching / detaching portion 6.

As shown in FIG. 2 in an enlarged manner, the lock ring 8 has a screw 14 screwed onto the bit attaching / detaching portion 6, is formed in a substantially bowl shape, and a sliding contact portion 15 is formed on the opening edge thereof. ing.

The sliding contact portion 15 is formed of a tapered surface formed between the sliding contact portion 15 and the bit attaching / detaching portion 6 which is the end portion on the bit holder side.
Are eccentric to each other.

For this reason, when the sliding contact portion 15 comes into contact by screwing the screw 14, a gap 16 is formed in a part thereof, and the gap 16 becomes smaller as the screw 14 is screwed more.

In the impact tool having such a configuration, when the bit (not shown) is fitted into the bit attaching / detaching portion 6, the locking body 7 holds the bit.

When the lock ring 8 is moved toward the drive unit 9 side in the axial direction against the spring 10, the space 11 enables the lock body 7 to move the lock body 7 outward in the radial direction. 7
Does not affect the bit, and the bit can be attached and detached.

Further, the bit acts so as to be struck in the axial direction by the driving unit 9 and rotated by the locking body 7 so as to be able to pierce concrete or the like.

Therefore, the bit produces a violent vibration, which is
It acts on the cap 12 screwed to the bit attaching / detaching portion 6.

However, since the sliding contact portion 15 formed between the cap 12 and the bit attaching / detaching portion 6 is eccentric to each other, when the cap 12 is screwed, the sliding contact state due to the eccentricity in the rotation direction of the cap 12 is caused. Changes, and in particular, large friction occurs in the rotational direction when the parts that are unevenly distributed toward the axis come into contact with each other.

For this reason, when the cap 12 is assembled, a large amount of friction is generated at a constant angle. However, if the cap 12 is forcibly assembled to some extent, the same friction is generated when the cap 12 is loosened.

In particular, since the cap 12 is configured in a bowl shape, even if a large friction is generated at a certain angle at the sliding contact portions 15 that are eccentric to each other, the cap 12 can be slightly deformed and forcibly screwed. is there.

By being assembled in this way, the cap 12 does not loosen even by violent vibration and impact, and the assembled state can be maintained.

Further, since the cap 12 is a component close to a bit, it is made of steel material because it hits concrete fragments to be punched, etc., but is configured in a bowl shape in the radial direction because of the sliding contact portion 15. It is convenient for deformation, and it is better to carry out quenching after performing eccentric processing.

The eccentric tapered surface forming the sliding contact portion 15 is
When configured near the opening edge of the cap 12, the cap 12
This is convenient because the effect of the deformation can be increased.

[Advantages of the Invention] According to the present invention, it is convenient to assemble and disassemble the part of the bit holder, and the assembled state can be maintained even if a shock or a fragment of the processing material collides, and the size is increased in the axial direction. Because it does not do, it is convenient for small size, the effect is
It is extremely large.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of an impact tool according to an embodiment of the present invention, and FIG. 2 is an enlarged vertical sectional view of the main part. FIG. 3 is a longitudinal sectional view showing a main part of a conventional impact tool. 6 ... Bit attaching / detaching part, 7 ... Locking body, 8 ... Lock ring, 9 ... Drive part, 10 ... Spring, 12 ... Cap, 15 ... Sliding contact part

Claims (1)

[Claims] 1. An impact tool for striking a bit, wherein a screw is formed on the outer periphery of the end of the bit holder, and a bowl-shaped cap screwed to the end of the screw is provided, and the cap has a tapered surface. An impact tool characterized in that a sliding contact portion that is pressed against the formed bit holder side is formed, the axes of the sliding contact portions are eccentric to each other, and the bit holder is assembled by this cap.