JPH0871933A - Impact wrench limiter - Google Patents

Abstract

PURPOSE: To prevent an excessive fastening force from being acted on a thread to be fastened in the case where a screw is fastened using a high torque type impact wrench. CONSTITUTION: An impact wrench limiter has an input shaft 8 connected to the driving shaft of the impact wrench and an output shaft 9 connected to a socket, and clutch plates 6, 7 to slip when a load above a fixed value acts on the output shaft are provided between the input shaft 8 and the output shaft 9. Even when a screw is fastened by the high torque impact wrench, excessive fastening force does not act on the fastened screw, and the rupture accident of the fastened screw can therefore be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact wrench limiter for use in a high torque impact wrench used for tightening and removing large screws.

[0002]

2. Description of the Related Art The size of a mounting screw used for mounting a tire wheel of a bus, a truck, etc. on an axle is generally large, and is used for tightening or removing these large size screws. An impact wrench is used as a tool.

Further, the size (strength) of the impact wrench used for the screwdriver work for attaching or detaching the tire wheel of the bus, truck or the like is selected particularly when the tire wheel is fastened. Considering the rusting of the screw, it is effective in operation to select and use a large impact wrench having a torque strength of 1 rank to 2 rank higher than the size of the mounting screw.

[0004]

However, the use of a large impact wrench, which is a model higher than ranks 1 to 2 with respect to the above large screw size, makes it difficult to remove rusted screws as described above. Although it is advantageous, if you tighten the mounting screw of the above size with a large impact wrench of the higher model, the torque of the impact wrench is high and the screw will be overtightened and the screw will break, Since the tightening force must be adjusted in order to prevent breakage accidents, there were problems such as variations in screw tightening.

In order to solve this problem, a tightening impact wrench capable of obtaining a tightening torque suitable for the size of the mounting screw and a dismounting impact wrench having a torque 10 to 20% larger than the tightening torque. It is possible to use two types of impact wrench to install or remove large screws, but this requires replacement of the impact wrench every time the screw is attached or removed, resulting in poor workability. Moreover, there is a problem that the facility is not economical.

[0006]

The present invention has been made in view of the above problems, and is used by being attached to a drive shaft of an impact wrench having an output torque larger than a limit tightening torque value of a screw to be tightened. The limiter has an input shaft connected to the drive shaft and an output shaft connected to a socket, and a load of a predetermined amount or more is applied to the output shaft between the input shaft and the output shaft. Even if the output torque of the impact wrench is large, a clutch plate that causes slippage when acted on should be provided so that excessive tightening torque is not applied to the tightened screw so that the tightened screw has the desired torque. An object of the present invention is to provide an impact wrench limiter that can be tightened with a torque value, and further that can prevent breakage accidents of screws to be tightened.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments shown in the drawings.

FIG. 1 shows a well-known impact wrench 1, on which a drive shaft 2 of the impact wrench 1 is removably attached with sockets 3 of various sizes adapted to the size of a tightening screw (not shown). I will get it.

FIG. 2 shows the drive shaft 2 of the impact wrench 1.
Then, the limiter 4 of the embodiment of the present invention is attached, and the socket 3 is connected to the limiter 4. That is, when removing (loosening) a large tightening screw, as shown in FIG. 1, the socket 3 is directly fitted to the drive shaft 2 of the impact wrench for use. As shown in FIG. 2, the drive shaft 2 of the impact wrench is used by connecting the socket 3 via the limiter 4.

The structure of the limiter 4 will be described below.

In FIGS. 3 and 4, reference numeral 5 denotes a cylindrical case. Inside the cylindrical case 5, a mountain-shaped inclined surface 6'is formed on one end surface of the annular case. A first clutch plate 6 and a second clutch plate 7 forming a mountain-shaped inclined surface 7'which is surface-bonded corresponding to the mountain-shaped inclined surface 6 ', and a central axis of the first clutch plate 6 The input shaft 8 is integrally formed on the line. An output shaft 9 is integrally formed on the center axis of the second clutch plate 7, and the input shaft 8 and the output shaft 9 are provided so as to project from both end surfaces of the tubular case 5.

Reference numeral 10 is provided in the cylindrical case 5,
A large number of disc springs that elastically join the first clutch plate 6 and the second clutch plate 7, and the disc spring group is fixed to one side opening edge of the tubular case 5. It is elastically housed in the cylindrical case 5 by the retaining ring 11 that is formed. In addition, a shim 12 of various sizes for adjusting the elastic force of the disc spring group is exchangeably interposed between the retaining ring 11 and the disc spring group. The input shaft 8 is formed with a shaft hole 13 into which the drive shaft of the impact wrench is fitted.

The structure of the limiter 4 according to this embodiment has been described above. Next, the operation will be described.

When the tightening screw is tightened by the high torque impact wrench 1 as described above, the limiter 4 is used by mounting the limiter on the drive shaft 2 of the impact wrench. That is, the input shaft 8 of the limiter is fitted into the drive shaft 2, the socket 3 is fitted into the output shaft 9 of the limiter, and the screws are tightened.

When the tightening torque value of the screw to be tightened becomes close to an appropriate value, the first clutch plate 6 and the second clutch plate 7 are resisted against the elastic force of the disc spring group in the limiter 4. Slips, and as a result, the rotational torque of the first clutch plate 6 is no longer transmitted to the second clutch plate 7, thereby avoiding transmission of excessive tightening force to the tightened screw.

That is, as shown in FIG. 5, when the tightening torque characteristic of only the impact wrench 1 is shown by the line A, a high tightening torque can be obtained with respect to the impact time. By using a limiter in which the Belleville spring group with elastic characteristics that can be controlled to the tightening torque indicated by the line B is installed in the wrench 1, even if the impact time is lengthened, the increase in the tightening torque is avoided. Since it is possible to prevent the screw to be tightened from being tightened with an excessive tightening torque, it is possible to prevent a screw breakage accident when the screw is tightened.

When loosening the screw, the limiter 4 is used.
If the screw is removed and the screw is removed in the state shown in FIG. 1, the rusted screw can be effectively removed due to the high output of the impact wrench.

[0018]

As described above, according to the present invention, the first clutch plate integrally having the input shaft connected to the drive shaft of the impact wrench and the second clutch plate frictionally coupled to the first clutch plate are provided.
Clutch plate, an output shaft integrally formed with the second clutch plate and capable of fitting and holding a socket, and a plate for elastically press-contacting the first clutch plate and the second clutch plate. Since it is equipped with a spring group, by using this limiter, for example, when tightening the screw with an impact wrench having a tightening torque greater than the strength of the screw to be tightened, the tightening strength close to the limit strength of the screw is tightened. When the applied torque is reached, there is an effect that the limiter operates and the breakage of the screw can be prevented in advance.

[Brief description of drawings]

FIG. 1 is an external view of an impact wrench.

FIG. 2 is an external view of an impact wrench to which the limiter of the present invention is attached.

FIG. 3 is an explanatory diagram showing an internal structure of a limiter according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an operating state of a limiter according to the embodiment of the present invention.

FIG. 5 is a characteristic diagram showing tightening torque and impact time.

[Explanation of symbols]

1 ... Impact wrench 2 ... Drive shaft 3 ... Socket 4 ... Limiter 5 ... Case 6 ... First clutch plate 7 ... Second clutch plate 8 ... Input shaft 9 ... Output shaft 10 ... Disc spring 11 ... Retaining ring 12 ... Shim 13 ... Shaft hole

Claims (1)

[Claims] 1. A first clutch plate integrally having an input shaft connected to a drive shaft of an impact wrench, a second clutch plate frictionally coupled to the first clutch plate, and a second clutch plate. And a disc spring group for elastically press-contacting the first clutch plate and the second clutch plate. Impact wrench limiter.