JP2002254335A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen reduction in tightening capacity, minimize an overall tool length, ensure sufficient strength and life, and reduce noise during operation. SOLUTION: An anvil is divided into two parts 10' and 12', and a buffering means is included in a torque transmitting means, so that a design compact but large in buffering capacity is possible, the strength and life of the anvil are improved and reduction in tightening capacity is lessened. The torque transmitting means is a mechanism using balls 18, rollers 19 or the like as key elements and providing the two anvils with grooves in which the key elements are fitted, so that smoother buffering is possible and heat generation is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power tool such as a rotary impact tool, and more particularly, to a power tool for reducing noise.

[0002]

2. Description of the Related Art A rotary impact tool as an electric tool is widely used at present because of its small reaction force and high fastening ability. However, the noise is loud due to the mechanism using the impact, which is a problem.

FIG. 6 is a cross-sectional view of the general structure of a general rotary impact tool conventionally used. Denti pack 1
Is used as a power source, the driving mechanism of the motor 5 is operated to drive the hitting mechanism, and the anvil 20 is hit.
To give a rotary impact.

In the above-mentioned impact mechanism, the driving force of the motor 5 rotates the spindle 13 via the planetary gear mechanism 6. The spindle 13 and the hammer 9 are connected to the cam ball 14 and the V
They are connected by a cam mechanism composed of a cam groove 13a. Further, the hammer 9 is constantly urged in the distal direction by the spring 8. Thereby, the spindle 1
3. When the hammer 9 is relatively twisted, the hammer 9 retreats toward the motor 5, and when released from the twist, the hammer 9 rotates and advances while being accelerated by the spring 8. Further, the hammer 9 and the anvil 20 respectively have convex portions 9a and 20a symmetrically arranged at two positions on the rotation plane. Screw 2
2. The rotating direction of the tip tool 17 and the anvil 20 is mutually restricted.

[0005] With such a configuration, the operation of the rotary hitting proceeds as follows. The rotational force of the spindle 13 is transmitted to the hammer 9 via the cam mechanism, and starts to rotate together. The protrusions of the hammer 9 and the anvil 20 are fitted before the half rotation. The spindle 13 and the hammer 9 are relatively twisted, and the hammer 9 starts to retract while contracting the spring 8. Eventually, the height of the protrusion is overcome, and the fitting is released. The hammer 9 adds to the rotational force of the spindle 13,
The spring 8 is rapidly accelerated in the rotational direction by the elastic energy stored in the spring 8 and starts moving forward. While the hammer 9 is being accelerated, the projections are fitted again. At this time, a strong rotary impact force is applied to the anvil 20 and transmitted to the fastening object 23. And the hammer 9 starts retreating again.

The above is the cycle of the rotary impact. In this cycle, the hammer 9 performs the forward and backward movement simultaneously with the rotational movement. These movements become the source of vibration and the anvil 2
0, the fastening object 23 is vibrated in the axial direction via the tip tool 17.

[0007] It is known that the noise energy from the fastening object 23 occupies a large proportion of the noise during the operation using the rotary impact tool. In order to reduce the noise, it is first determined that the exciting force transmitted to the fastening target 23 is reduced. FIGS. 7 to 9 show a rotary impact tool proposed in Japanese Patent Application Laid-Open No. Hei 7-237152. The structure of the rotary impact tool is divided into two parts, and includes a torque transmitting means and a means for absorbing an axial force. I have. That is, the anvils 10, 12 divided into two parts are fitted to each other so as to be non-rotatable and slidable in the axial direction.
Are arranged in the gap. With such a structure, the axial vibration force transmitted to the member to be tightened is reduced, and
3 is realized.

However, in the above structure, if the total length of the tool is not increased, the space for the cushioning material is limited to the space between the two divided anvils 10 and 12, and the space must be reduced. Was. Further, since the shape of the cushioning material is a thin plate shape and the area in the radial direction is large, the elastic modulus of compression is necessarily high. For this reason, if the total length of the tool is not increased, the stroke, which is an important element of the buffering capacity, cannot be increased, and the vibration reduction force cannot be significantly reduced, and the effect of noise reduction can be increased. Did not.

As a countermeasure for noise reduction, it is effective to increase the cushioning stroke by reducing the cushioning material in the stroke direction (axial direction) and reducing the area in the radial direction. However, if the cushioning material is to be enlarged in the axial direction, the total length of the tool must be increased, and the usability in a narrow place becomes poor. The problem was how to make the buffer stroke longer while keeping the overall length of the tool down.

It is preferable that the sliding of the fitting portion between the anvils 10 and 12 be smooth even when a rotary impact torque is applied. This is because, in a rotary impact tool, the generation of torque and the generation of an exciting force in the axial direction occur at the same time, so that the frictional force increases when the cushioning function should be performed. The smaller the frictional force is, the better from the viewpoints of smooth buffering of the excitation force and preventing abrasion. In particular, in a structure in which the sliding surface has a large pressure angle, such as when a square shape is used for fitting, a problem occurs in that the surface pressure is large and the surface is easily worn, and a problem that the sliding is extremely troublesome due to easy galling.
In order to reduce the frictional force and surface pressure of the fitting part, it is effective to increase the diameter of the fitting part.

There is also a problem that the fastening ability is reduced. The reason for this is that the rigidity is reduced due to the two parts of the anvil, and play in the rotation direction is caused.

[0012]

In the prior art, the overall length of the tool must be increased in order to increase the buffering capacity of the axial exciting force applied to the fastening object and increase the effect of noise reduction. Did not. Another problem is that the fastening ability is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power tool having a compact overall length of a tool, ensuring sufficient strength and life, improving a buffer capacity, increasing a noise reduction effect, and reducing a decrease in a tightening capacity. It is to provide.

[0014]

In order to achieve the above object, according to the first aspect of the present invention, an anvil provided with a means for connecting a tool bit is separated into two parts, and a torque transmitting means and a buffer are provided between the parts. In the power tool provided with the means, the shock absorbing means is included inside the torque transmitting means.

According to a second aspect of the present invention, in the first aspect of the invention, the torque transmitting means is connected between the anvils by a spline mechanism.

According to a third aspect of the present invention, in the second aspect of the present invention, the spline mechanism uses a rollable component such as a ball or a roller as a key element, and has grooves formed in the two anvils to be fitted with the key element. It is characterized by having.

According to the first aspect of the present invention, the anvil is separated into two parts, and the buffering means is included inside the torque transmitting means provided between the parts, so that the buffering stroke can be increased while keeping the total tool length compact. can do.

According to the second aspect of the present invention, the torque transmission means is formed by spline fitting, thereby preventing galling.

According to the third aspect of the present invention, the torque transmitting means is a spline mechanism in which a ball, a roller, or the like is used as a key element and a groove for fitting the key element is provided in two anvils. Buffering is possible and heat generation is reduced.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the power tool according to the present invention will be described. The present embodiment is applied to a cordless hand-held rotary impact tool that uses a Dentipack as a power source and a motor as a drive source. FIG. 1 is a sectional view of an embodiment of the present invention. Portions other than the anvil, such as the configuration of the impact mechanism, are as described in the section of the conventional rotary impact tool. In other portions, the shape of the hammer case 7 "and the metal 15" is changed in accordance with the shape change of the anvil.

The anvil comprises a first anvil 10 ', a second anvil 12', and a damper 11 '. The first anvil 10 'and the second anvil 12' are fitted by an involute spline 10b as shown in FIG.
A damper 11 ′ is provided inside thereof. Damper 1
1 'is a rubber material, is cylindrical in shape, and has a column height of about 2 mm between the first anvil 10 and the second anvil 12'.
Is a dimension where a gap is generated.

According to the above-described anvil structure, the exciting force in the axial direction from the impact mechanism is buffered by the damper 11 ', so that the exciting force applied to the fastening object 23 is reduced. The anvils may be fitted together using a square spline as shown in FIG.

As for the buffering capacity, the compression elastic modulus is reduced by reducing the diameter of the damper 11 ', and the strain on the stroke is relatively reduced by increasing the axial direction. As a result, the buffer stroke can be increased without impairing the life of the damper 11 '. Further, galling does not occur due to the spline fitting. Therefore, a large buffer capacity can be obtained stably.

As for the tightening ability, the diameter of the fitting portion, which is the torque transmitting means, is larger than that of the conventional product, so that the torsional rigidity of the entire anvil is large. Further, since the load applied to the spline teeth is reduced, the strength and wear resistance are improved. Further, since the diameter of the fitting portion is large, the influence of the gap between the spline teeth on the rotation angle is small, and the play in the rotation direction is small. Therefore, the strength is sufficient and the decrease in the tightening ability is small.

With respect to the total length of the tool, the damper 11 'is arranged inside the spline fitting portion to suppress the extension of the total length.

FIG. 4 is a sectional view of a main part of a rotary impact tool showing another embodiment of the present invention. The torque transmission means of the above-described embodiment is changed from the involute spline 10b to FIG.
The configuration has been changed to a ball spline as shown in FIG.
Even when torque is applied to the anvil, the sliding resistance is very small, so that the vibration can be more smoothly absorbed. Also,
Since the generation of frictional heat is reduced, temperature rise is suppressed,
This leads to an increase in the life of the damper 11 '. The same effect can be obtained by using a structure using rollers and square grooves as shown in FIG. Further, a structure using rollers and round grooves shown in FIG. In this structure, the sliding resistance is not so small, but is superior in strength to the above two examples.

[0027]

According to the present invention, the anvil provided with the means for connecting the tip tool is separated into two parts, and the torque transmission means and the buffer means are provided between the parts, so that the noise generated from the fastening object is obtained. Is greatly reduced. Further, by including the shock absorbing means inside the torque transmitting means, it is possible to design the tool with a large shock absorbing stroke while keeping the total tool length compact.

In addition, since the torque transmitting means connects the anvils with splines, the surface pressure is reduced, the abrasion is reduced, and galling does not occur.

Further, by using a mechanism in which a rollable component such as a ball or a roller is used as a key element and a groove for fitting with the key element is provided in the two anvils, friction is reduced. This has made it possible to absorb vibration more smoothly, reduce the temperature rise, and ensure the life of the damper.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rotary impact tool as an embodiment of a power tool according to the present invention.

FIG. 2 is a partial cross-sectional view of the striking mechanism shown in FIG.

3A and 3B are cross-sectional views of the anvils shown in FIG. 2 when viewed from the axial direction. FIG. 3A is a diagram illustrating an example using an involute spline, and FIG. 3B is a diagram illustrating an example using a square spline.

FIG. 4 is a cross-sectional view of a striking mechanism showing another embodiment of the rotary striking tool to which the present invention is applied.

5A and 5B are cross-sectional views of the fitting of the anvils in FIG. 4 as viewed from the axial direction, wherein FIG. 5A is an example using a ball and a round groove, FIG. () Is a diagram showing an example using a roller and a round groove.

FIG. 6 is a sectional view showing an example of a conventional rotary impact tool.

FIG. 7 is a sectional view of a rotary impact tool having a conventional low noise structure.

8 is a cross-sectional view of the striking mechanism shown in FIG.

9 is a cross-sectional view of the fitting of the anvils in FIG. 8 as viewed from the axial direction.

[Explanation of symbols]

1 ... Denti pack, 2 ... Terminal, 3 ... Housing,
4 switch, 5 motor, 6 planetary gear mechanism, 7 hammer case, 8 spring, 9 hammer, 9a hammer projection, 10 first anvil, 10a anvil projection,
10b: involute spline, 11: damper, 1
2 ... second anvil, 13 ... spindle, 13a ... V-shaped cam groove, 14 ... cam ball, 15 ... metal, 16 ... oil seal, 17 ... tip tool, 18 ... ball, 19 ... roller, 20 ... anvil, 20a ... Anvil convex portion, 21: washer, 22: screw, 23: fastening object.

Claims (3)

[Claims] 1. An electric tool having an anvil provided with a means for connecting a tip tool, separated into two parts and provided with a torque transmitting means and a buffer means between the parts, wherein the buffer means is included inside the torque transmitting means. An electric tool characterized by having been made. 2. An electric tool according to claim 1, wherein said torque transmitting means is connected between said anvils by a spline mechanism. 3. The spline mechanism according to claim 2, wherein a rollable part such as a ball and a roller is used as a key element, and grooves for fitting the key element are provided on the two anvils. Power tools.