JPH0735734Y2 - Impact driver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an impact driver used for loosening screws or nuts that are rusty and difficult to remove by impact, or for finally tightening screws or the like.

(Prior art and its technical problem) In a fixing structure using screws, the screws and the mounting members or nuts often stick together due to the generation of rust over time.
In such a case, it cannot be removed with an ordinary screwdriver or spanner.

As a countermeasure against this, when it is permissible to destroy the screw or screw hole, use a chisel or a gas fusing machine to remove it, but if you want to use the screw hole or mounting member again, hammer the head of the driver. Hit with to give a shock and remove the screw.

Recently, instead of simply giving an impact to the screw head, the impact of the hammer is converted into a turning torque by using a cam mechanism, and a large instantaneous turning torque is generated in the bit of the driver. A driver that can be removed without destroying the
That is, a hammer impact driver as shown in FIGS. 8 and 9 has been proposed.

The impact driver shown in FIGS. 8 and 9 is composed of a tubular casing 42, a cam mechanism, a chuck 12 and the like, and the casing 42 has a solid weight portion 43 at the upper portion in order to secure the mass. There is. The handle 12a of the chuck 12 is rotatably fitted in the recess 44 of the casing 42, and the cam mechanism is composed of the ball 15, the V-shaped groove 14 and the like, and between the casing 42 and the chuck handle 12a. It is provided so as to convert the axial movement of the casing 42 into the rotational movement of the chuck 12.

When the operator hits the top wall of the casing 42 with a hammer, the entire casing is momentarily lowered as shown in FIG. 9, and the bit of the chuck 12 is momentarily rotated with a large rotation torque. ing.

However, as described above, the entire casing 42 having a large mass is hit to lower the entire casing 42,
Since the shock is transmitted from the to the chuck 12 via the cam mechanism, the torque loss in the transmission path is large. Moreover, since a large impact is required, the mounting member may be destroyed.

(Object of the Invention) The object of the present invention is that a large hammer is not required, a large turning torque can be momentarily applied to the chuck, the efficiency of transmitting an impact force to the chuck is good, and a large impact force is required. Therefore, it is an object of the present invention to provide an impact driver that does not damage the mounting member or the like.

(Technical Means for Achieving the Purpose) In order to achieve the above object, the present invention relates to a bottomed cylindrical slider having a top wall fitted axially movably in a cylindrical casing and a rotation preventing mechanism. And the return spring urges the slider toward the top wall so that the slider top wall projects as a hammer striking wall from the end of the casing. Is rotatably and axially movable, and a cam mechanism is provided between the slider and the chuck for converting the axial movement of the slider into the rotational movement of the chuck.

(Operation) With the casing in hand, the bit at the tip of the driver is engaged with the screw head (or nut), and the hammer directly strikes the top wall of the slider to give an impact.

Then, the slider is instantaneously lowered with respect to the casing and the chuck, and the impact force in the axial direction of the slider is converted into the rotational movement of the chuck by the cam mechanism, and a large instantaneous rotational torque is generated in the chuck. The screw is loosened by the dynamic torque and the impact force.

(Embodiment 1) FIGS. 1 to 4 show a first embodiment of the present invention in which the opening side (bit mounting side) of the casing 1 is provisionally set to the lower side. In FIG. 1, a cylindrical casing 1 has upper and lower open ends and integrally has an inward flange 1a for retaining a spring and retaining at the lower end edge, and the casing 1 has a diameter at the center in the vertical direction. A detent pin 6 is fixed to pass through in the direction. In the casing 1,
A bottomed cylindrical slider 2 having a top wall 4 at the upper end is fitted so as to be movable in the axial direction, and the slider 2 has a pair of rotation-preventing elongated holes 7 extending in the axial direction. Engages with the pin 6, thereby preventing the slider 2 from rotating and regulating the axial movement range. A return spring 8 is contracted between the lower end of the slider 2 and the inward flange 1a. The return spring 8 urges the slider 2 upward so that the regulating pin 6 contacts the lower end edge of the elongated hole 7. By contacting each other, the slider 2 is maintained in a state in which the top wall 4 projects from the upper end edge of the casing 1.

The slider 2 is provided on the inner peripheral surface of the slide 2 on the opening side (lower end side).
The handle 12a of the chuck 12 is rotatably and axially movable relative to the chuck 12, and a cross-shaped bit 13 is held at the lower end of the chuck 12, for example. The bit 13 is replaceable with respect to the chuck 12, and the chuck 12 is also replaceable with respect to the handle 12a. Therefore, the bit 13 can be cross-shaped, minus-shaped or 6
You can replace the square shaft type, and also chuck 12
It itself can be replaced with, for example, a socket having a polygonal hole.

Between the handle 12a of the chuck 12 and the slider 2, a cam composed of a pair of cam grooves 14 and a pair of steel balls 15 is provided to convert the axial movement of the slider 2 into the rotational movement of the chuck 12. A mechanism is provided. That is, in FIG. 3, a pair of ball holding holes 17 are formed in the slider 2 at opposite positions, and the balls 15 are rotatably fitted in the holding holes 17, respectively. It protrudes inward. The cam groove 14 is formed on the outer peripheral surface of the chuck handle 12a and is formed in a V shape (or heart shape) that opens upward, and a part of the ball 15 can roll in the cam groove 14. Is engaged with. The upper end of the chuck handle 12a and the first
A return spring 20 for a cam is contracted between the regulating pins 6 in the figure, and the return spring 20 urges the chuck 12 downward so that the ball returns to the upper end standby position of the cam groove 14.
15 is maintained.

2 shows an enlarged view of the II-II section of FIG.
The structure of the detent mechanism by the restriction pin 6 and the long hole 7 is clarified.

The operation will be described. FIG. 1 shows a state before hitting with a hammer. The top wall 4 of the slider 2 is projected from the upper end edge of the casing 1 by the elastic force of the return spring 8, and the chuck 12
Is urged downward by the cam return spring 20
15 is located at the upper end standby position of the cam groove 14. In this state, the operator holds the casing 1 with one hand and
For example, 13 is fitted in the groove of the screw head, and while holding the hammer with the other hand, strikes the slider top wall 4 to give an impact.

Then, as shown in FIG. 4, the slider 2 momentarily descends with respect to the casing 1 in a stationary state while compressing the return spring 8, and the ball 15 also descends together with the return spring 8, and the cam action with the cam groove 14 causes chucking. Momentarily rotate 12 in the direction of arrow A1 within a small rotation range to loosen the screw.

When the above operation is completed, the restoring force of the return spring 8 and the cam return spring 20 restores the state of FIG. 1, and the ball 15 returns to the upper end standby position of the cam groove 14.

The above operation is, for example, an operation of rotating the chuck 12 in the direction of arrow A1 (counterclockwise) in order to loosen the right screw, but when tightening the screw tightly or loosening the left screw,
Rotate the chuck 12 in the direction of arrow A1 from the state shown in FIG.
The ball 15 is positioned at the other upper end standby position of the cam groove 14, that is, at the left upper end position in FIG. Then, when the slider 2 is hit, the chuck 12 rotates in the A2 direction.

(Embodiment 2) FIG. 5 shows a modification of the slider. The slider 2 is divided into an upper member 2a and a lower member 2b, and an elongated hole 7 is formed in the lower member 2b. Is equipped with a top wall 4. The upper member 2a has a step portion 25 for a stopper, and a retaining snap ring 26 is fitted on the inner peripheral surface of the upper end of the casing 1.

(Embodiment 3) The embodiment shown in FIG. 6 is an example in which a snap ring 27 is fitted to the lower end of the casing 1 as a spring receiving and retaining member.

(Embodiment 4) FIG. 7 shows that a ball tray 29 is arranged in the ball holding hole 17,
This is an example in which the movement of the ball 15 is smoothed and the cam function is improved.

(Effects of the Invention) According to the present invention as described above: (1) A casing 1 that is held by hand to hold a driver,
Separated from the slider 2 that is directly hit by a hammer, the impact force is not transmitted to the casing 1, and only the slider 2 is momentarily lowered to chuck through a cam mechanism.
Since the rotation torque is generated in 12, the impact force in the impact transmission path is greater than in the conventional structure in which the entire casing having a large mass is directly hit and transmitted from the casing to the chuck via the cam mechanism. Transmission efficiency is improved.

Therefore, it is possible to generate a sufficiently large turning torque without giving a large impact force with a large hammer, and there is no fear of damaging the mounting member.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view (I-I sectional view of FIG. 2) of a first embodiment of an impact driver to which the present invention is applied, and FIG. 2 is an enlarged sectional view of II-II section of FIG. 1, and FIG. 2 is a partial sectional view taken along the line III-III in FIG. 2, FIG. 4 is a vertical sectional view showing the state of the driver of FIG. 1 when hit, FIG. 5 is a vertical sectional view of the second embodiment, and FIG. FIG. 7 is a vertical cross-sectional partial view of the third embodiment, FIG. 7 is a vertical cross-sectional partial view of the fourth embodiment, FIG. 8 is a vertical cross-sectional view of a conventional example, and FIG. 9 is a vertical cross-sectional view of the driver of FIG. It is a side view. 1 ...
Casing, 2 ... Slider, 4 ... Top wall, 6, 7 ... Restriction pin, Long hole (an example of a rotation stopping mechanism), 8 ... Return spring,
12 ... Chuck, 14, 15 ... Cam groove, ball (1 of cam mechanism
Example)

Claims (1)

[Scope of utility model registration request] 1. A bottomed cylindrical slider having a top wall is axially movably fitted in a cylindrical casing and is prevented from rotating by a detent mechanism, and a slider is biased toward the top wall by a return spring. The slider top wall as a hammer striking wall so as to project from the end edge of the casing, and a chuck for bit holding is fitted on the inner peripheral surface on the opening side of the slider so as to be rotatable and axially movable. Between the chuck,
An impact driver including a cam mechanism for converting the axial movement of the slider into the rotational movement of the chuck.