JPH11320432A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a fall of a steel ball at the impact mechanism of an impact tool. SOLUTION: This tool comprises a spindle 3 rotated by a drive part; a hammer 5 movable axially of a spindle 3; a hammer cam 6 formed at a hammer 5; a spindle cam 4 formed at a spindle 3; a steel ball 7 engaged with the spindle cam 4 and the hammer cam 6; a spring 8 always energizing the hammer 5 against the opposite drive part side; and a washer 31 supporting one end of the spring 8. In this case, the spindle 3 is provided with an elastic body 30 having an inside diameter lower than the shaft diameter of the spindle 3 and an opening with size lower than the inside diameter is arranged from a direction orthogonal to the axial direction of the spindle 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for preventing a steel ball from falling off in a striking mechanism of an impact tool.

[0002]

2. Description of the Related Art As shown in FIGS. 6 and 7, a conventional impact tool includes a drive unit built in a housing 1 and a spindle 3 transmitting the rotational force of the drive unit via a gear mechanism 2. A steel ball 7 interposed between a spindle cam 4 formed on the spindle 3 and a hammer cam 6 formed on the hammer 5, a hammer claw 9 formed on the hammer 5, and an anvil claw 1 formed on the anvil 10;
1 is engaged with the hammer 5 on the side opposite to the drive unit (A in FIG. 1).
(Direction). The hammer 5 and the anvil 1 that have been integrally rotated when a load not less than a predetermined load is applied to a tip tool (not shown).
At 0, the hammer claw 9 and the anvil claw 11 repeat engagement and disengagement. At this time, the hammer 5 slides on the spindle 3 axis along the leads of the cams 4 and 6 by the steel ball 7 interposed between the spindle cam 4 and the hammer cam 6, so that the impact force is exerted on the anvil 10. Will be added. Further, the hammer 5 is moved by a distance La toward the drive unit (in the direction B in FIG. 1) until the hammer end surface 5a comes into contact with the spindle stepped portion 12 in order to interpose the steel ball 7 between the spindle cam 4 and the hammer cam 6. (Retreat), which secures an opening Sa larger than the outer diameter of the steel ball 7.

However, when the impact tool configured as described above is used, the retreat amount of the hammer 5 at the time of the normal impact is smaller than La, but various factors such as the rotation speed of the drive unit and the type of the work material are used. Since the hammer 5 may retreat to the position where La = 0 depending on the hitting timing under the conditions, the steel balls 7 in both the cams 4 and 6 fall off from the opening Sa and this steel The ball 7 is between the hammer 5 and the hammer case 13 or the hammer claw 9
And bite between the anvil claws 11, and as a result,
There was a problem that the hammer case was damaged and the claws 9, 11 were damaged.

[0004] In order to solve the above-mentioned problem, the present applicant has proposed a steel ball falling-off prevention structure described in Utility Model Registration No. 251323. The configuration of Utility Model Registration No. 251323 will be described below with reference to FIGS. As shown in FIG. 8, in order to interpose a steel ball 7 between the spindle cam 4 formed on the spindle 3 and the hammer cam 6 formed on the hammer 5, a spring that constantly urges the hammer 5 toward the non-drive unit side. It is necessary to move the hammer 5 to the drive unit side as shown in FIG. As a result, an opening Sa having a dimension larger than the outer diameter of the steel ball 7 is secured. In this state, after the steel ball 7 is inserted into both the cams 4 and 6, when the force Fa pressing the drive unit is released, the hammer 5 moves to the opposite drive unit due to the elastic force of the compressed spring 8. I do. After the movement, as shown in FIG.
The end face 16a of the washer 16a is moved toward the opposite side of the drive unit by a distance Lc against the spring 8 by the force Fx of the hammer end face 5a.
A gap is provided between a and the outer diameter of the reduction section of the spindle 3. After arranging the two-piece locking pieces 17 and 18 shown in FIG. 11 in this gap using a special jig (not shown), and removing the push rod 20 ′, the hammer 5 becomes elastic with the spring 8 as shown in FIG. By the force, the hammer end face 5a is moved backward to a position where it comes into contact with the locking pieces 17,18. Therefore, even if an abnormal impact occurs due to an external factor as described above, the hammer 5 does not move to the maximum retreat position where La = 0 due to the locking pieces 17 and 18, and always secures the opening Sb. Because you can
The steel balls 7 are prevented from falling off from inside the cams 4 and 6. Here, the special jig is a push rod 2
This is a positioning jig for securely and easily arranging the locking pieces 17 and 18 on the inner diameter of the washer 16 which retreats to the driving section side by the elastic force of the spring when the 0 'is removed.

[0005]

In the above construction, a special jig is used when the two-piece locking piece is arranged between the hammer and the spindle. There is a problem that the number of parts is increased and the cost is increased due to the split product.

An object of the present invention is to solve the above problems and provide an inexpensive impact tool excellent in assemblability.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a driving unit, a spindle rotated by the driving unit, a hammer movable in the axial direction of the spindle, a hammer cam formed on the hammer, and a spindle formed on the spindle. And an impact tool comprising a spindle cam, a steel ball engaged with the spindle cam and the hammer cam, and a spring which constantly urges the hammer toward the non-drive unit side. This is achieved by disposing a regulating member having an inner diameter smaller than the shaft diameter of the spindle and having an opening smaller than the inner diameter from the direction perpendicular to the spindle.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An impact tool according to this embodiment will be described with reference to FIGS. FIG. 1 is a partially longitudinal side view showing the impact mechanism of the impact tool, and FIG.
FIG. 3 is a partially longitudinal side view showing a state where a steel ball 7 can be inserted into the spindle cam 6, FIG. 3 is a partially longitudinal side view showing a state when an elastic body 30 as a regulating member is incorporated, and FIG. FIG. 5 is a partially longitudinal side view showing a state in which the elastic body 30 is incorporated.

The impact mechanism of the impact tool includes, as shown in FIG. 1, a drive unit incorporated in a housing 1, a spindle 3 for transmitting the rotational force of the drive unit via a gear mechanism unit 2, and a spindle unit 3. Spindle cam 4 formed in 3
The hammer 5 is always counter-driven so that the steel ball 7 interposed between the hammer 5 and the hammer cam 6 formed on the hammer 5 is engaged with the hammer claw 9 formed on the hammer 5 and the anvil claw 11 formed on the anvil 10. A spring 8 that urges the unit (in the direction A in FIG. 1) and a C-shape disposed on the outer periphery of the shaft of the spindle 3 to regulate the amount of retraction of the hammer that moves toward the drive unit (in the direction B in FIG. 1). Elastic body 30 and an elastic body end face 3 located on the outer peripheral portion of the elastic body 30 and on the hammer side.
While receiving the spring 8 while supporting 0a,
And a washer 31 having an outer diameter larger than the outer diameter of the reduction section of the spindle 3.

The hammer 5 and the anvil 1 which rotate together when a load equal to or more than a predetermined value is applied to the tip tool.
The 0 hammer claw 9 and the anvil claw 11 repeat engagement and disengagement. At this time, the hammer 5 slides on the spindle 3 axis along the leads of the cams 4 and 6 by the steel ball 7 interposed between the spindle cam 4 and the hammer cam 6, thereby applying a striking force to the anvil 10. Is done.

In the impact mechanism of the impact tool thus configured, the spindle cam 4 and the hammer cam 6
The means for interposing the steel ball 7 therebetween will be described below. First, as shown in FIG. 2, the hammer 5 is moved backward by a distance La using a compression device or the like until the hammer end face 5a contacts the spindle end face 3a via the inner diameter of the washer 31 while compressing the spring 8. This position (La =
0), the hammer 5 is moved backward to rotate the spindle cam 4
An opening Sa having a diameter larger than the outer diameter of the steel ball 7 is formed between the hammer cam 6 and the hammer cam 6. This opening S
The steel ball 7 is inserted between the spindle cam 4 and the hammer cam 6 from a. After the insertion, as shown in FIG. 3, the washer 31 is moved against the spring 8 by the force F by the push rod 20 having an inner diameter larger than the outer diameter of the deceleration portion of the spindle 3 toward the counter-drive portion by a distance Lc. A gap is provided between the end face 5a and the outer diameter of the reduction section of the spindle 3. In this gap, an elastic body 30 having a notch S that is more deformable than the shaft diameter of the spindle 3 shown in FIG. 4 and having a thickness T is arranged from a direction perpendicular to the axial direction of the spindle 3. The elastic body 30 has an inner diameter L smaller than the shaft diameter of the spindle 3.
And an opening S (L> S) smaller than the inner diameter. Thus, the elastic body 30 can be reliably and easily incorporated into the spindle 3 while being elastically deformed. After the assembling work, when the push rod 20 is removed, the hammer 5 moves to a position where the hammer end face 5a and the elastic body end face 30a come into contact with each other by the elastic force of the spring 8. In this state, since the elastic body 30 is allowed to be substantially sealed by the spindle end face 3a, the hammer end face 5a, and the washer 31, it is only slightly deformed, and the thickness T of the elastic body 30 hardly changes. Thereby, the amount of backward movement of the hammer 5 can be regulated. In other words, the retreat movement amount of the hammer 5 at the time of normal impact is Lb or less, but the hammer 5 retreats to Lb or more from the impact timing under various conditions such as the rotation speed of the drive unit and the type of the work material,
Even if the hammer end face 5a abuts against the elastic body end face 30a, the elastic body 30 is only slightly deformed.
Since the steel ball 7 does not move, the steel ball 7 can be prevented from dropping out of the cams 4 and 6. here,
It is desirable to use the elastic body 30 which is rubber excellent in heat resistance and oil resistance and which does not elastically deform in the axial direction (thickness T).

In this embodiment, the amount of elastic deformation of the elastic body 30 in the axial direction is suppressed by the washer 31. However, especially when the elastic body 30 having a small deformation amount is used, the outer periphery of the elastic body 30 is not necessarily required. The washer 31 need not be provided.

As described above, the impact tool according to the present embodiment is simple in that the elastic body 30 is simply arranged from a direction perpendicular to the axial direction of the spindle 3 without using a special jig during assembly. By this means, the steel ball can be reliably and easily prevented from falling off, and the hammer 5
Since the elastic member 30 as a single component is used as the restricting member, the efficiency of the assembling operation can be improved, and the number of components can be reduced and an inexpensive steel ball drop-off configuration can be provided.

[0014]

According to the present invention, by providing a regulating member having a cutout portion arranged between the hammer, the spindle and the washer from a direction perpendicular to the axial direction of the spindle, the assembling is excellent and the cost is low. It is possible to provide a simple impact tool.

[Brief description of the drawings]

FIG. 1 is a partially longitudinal side view showing a striking mechanism of an impact tool according to the present invention.

FIG. 2 is a partially longitudinal side view showing a state in which a steel ball can be inserted into a hammer cam and a spindle cam according to the present invention.

FIG. 3 is a partially longitudinal side view showing a state when an elastic body according to the present invention is incorporated.

FIG. 4 is an external perspective view showing an elastic body according to the present invention.

FIG. 5 is a partially longitudinal side view showing a state where an elastic body according to the present invention is incorporated.

FIG. 6 is a partial longitudinal side view showing a conventional impact mechanism of an impact tool.

FIG. 7 is a partially longitudinal side view showing a conventional hammer at the time of maximum retreat.

FIG. 8 is a partially longitudinal side view showing a state in which a dividing member for restricting the movement amount of a hammer is arranged in a conventional impact mechanism of an impact tool.

FIG. 9 is a partially longitudinal side view showing a state in which a steel ball is inserted in a conventional impact mechanism.

FIG. 10 is a partially longitudinal side view showing a state in which a spring is compressed by a jig for disposing a dividing member in a conventional impact mechanism.

FIG. 11 is an external perspective view showing a conventional divided member.

FIG. 12 is a partially longitudinal side view showing a retracted state of a hammer regulated by a dividing member in a conventional impact mechanism.

[Explanation of symbols]

1 is a housing, 2 is a reduction gear, 3 is a spindle, 4 is a spindle cam, 5 is a hammer, 5a is a hammer end face, 6 is a hammer cam, 7 is a steel ball, 8 is a spring, 9 is a hammer claw, 10 is an anvil, 11 Denotes an anvil claw, 20 denotes a push rod, 30 denotes an elastic body, 30a denotes an end face of the elastic body, and 31 denotes a washer.

Claims (4)

[Claims] A driving unit, a spindle rotated by the driving unit, a hammer movable in the axial direction of the spindle, a hammer cam formed on the hammer, a spindle cam formed on the spindle, In an impact tool including a spindle cam, a steel ball that engages with the hammer cam, and a spring that constantly urges the hammer toward the non-drive unit side, the spindle is perpendicular to the axial direction of the spindle. An impact tool, wherein a restricting member having an inner diameter smaller than a shaft diameter of the spindle and having an opening smaller than the inner diameter is disposed from a direction of the impact tool. 2. The impact tool according to claim 1, wherein the regulating member is a C-shaped elastic body. 3. The impact tool according to claim 2, wherein the elastic body is rubber. 4. The impact tool according to claim 1, wherein the regulating member is disposed between a washer that receives the spindle and the spring.