JPH0521337Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a device that uses air pressure to prevent continuous striking motion of a striking element (hereinafter referred to as idling) when an electric hammer or the like is idling.

[Background of the idea]

In order to prevent dry firing, there has been a conventional method in which when the striker moves forward, it fits into the taper of a gripping member provided in front, and the striker is fixed by its gripping force. It is taken. The gripping member is usually a C-shaped cylindrical spring with a tapered inner diameter and cut at one point. When the striker enters the gripping member, the striker expands the taper of the gripping member and stops its movement due to the gripping force of the spring. Disadvantages of this device include the fact that friction when the striking element enters causes wear of the contact portion, which tends to reduce the gripping force and shortens the life of the gripping member.

[Purpose of invention]

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, extend the life of the dry-fire prevention device, and thereby prevent damage to the aircraft body.

[Summary of the idea]

The present invention provides a method of increasing the gripping force to a certain value or more in order for the gripping member to grip and fix the striking member, and increasing the friction when the impactor enters the gripping member and the gripping member. Focusing on the fact that there is a way to increase the energy consumed by the gripping member, in order to keep the gripping force small and increase the energy consumption, the gripping member is designed to increase the contact movement distance when the striker enters the gripping member. The support method was devised.

[Example of idea]

FIG. 1 is a longitudinal sectional side view showing an embodiment of the dry striking prevention device of the electric hammer according to the present invention. Similarly, FIG. 2 is a longitudinal side view showing a state in which the tool moves forward and the dry striking prevention device is activated. FIG. 3 is a partial longitudinal sectional side view showing an embodiment of the dry hitting prevention device according to the present invention. FIG. 4 is a partial longitudinal sectional side view showing a conventional dry hitting prevention device.

In the figure, the piston 8 reciprocates inside the striker 7, compresses and sucks the air inside the striker 7, and causes the striker 7 to strike the tool 1. The cylinder case 6 guides the striker 7 and holds the gripping member 4, the mouth washer 5, and the front cover 3. When the tool is released from the workpiece, the tool 1 struck by the striker 7 moves forward as shown in FIG. 2, hits the retainer 2, and stops. The striker 7 also follows this and jumps forward, enters the gripping member 4 while expanding its inner diameter, and stops.
In the prior art, the gripping member 4 is supported in the radial direction by the inner wall of the cylinder case 6, but since the outer diameter expands when the striker 7 enters, a gap is created in advance between the gripping member 4 and the cylinder case. be. Therefore, as shown in FIG.
There is a slight deviation in the axis of the ball when it is struck. For this reason, the gripping member 4 requires a groove to allow the striking member 7 to enter easily. Normally, the inner diameter of the gripping member 4 is tapered, and the diameter of the taper is enlarged by the amount of misalignment, so that it functions as a nozzle.

With this configuration, the distance over which the gripping member 4 and the striker 7 come into contact and slide while expanding the diameter of the gripping member 4 becomes considerably shorter than the length of the gripping member 4.

In order to reliably stop the striking motion of the striker 4, it is necessary that the energy absorbed by the expansion of the gripping member 4 is large, so if the sliding distance is short, the gripping force must be increased. .

As shown in FIG. 3, in the dry hitting prevention device of the present invention, the inner diameter of the grip member 4
Since the outer diameter of the mouth washer 5 is closely fitted to the inner diameter of the cylinder case 6, the axial center of the mouth washer 5 is regulated to match the axial center of the striker. Therefore, even if the above-mentioned crack is extremely small, its function is sufficient, and the striking element 7 makes contact with it.
The sliding distance while enlarging the diameter of the gripping member 4 can be extended over substantially the entire length of the gripping member 4.

As mentioned above, if the sliding distance is large, the gripping force can be relatively small, so the impactor 7 and the gripping member 4
The surface pressure of the contact area can be lowered. Therefore, wear is reduced and the life of the gripping member 4 can be increased.

FIG. 5 shows the relationship between the gripping force F of the gripping member and the approach distance L of the striker in the conventional dry hitting prevention device and the dry hitting preventing device according to the present invention. The gripping force of the gripping member of the present invention is OA′C′ for the conventional OAC. The energy required to expand the gripping member is represented by the areas of triangles ABC and A'B'C', respectively, and in this example, both are equal, but the gripping force itself is smaller in the present invention. OB represents the length of the gripping member,
OA and OA′ respectively indicate the length of the nozoki part.

[Effect of idea]

According to the present invention, the axial center of the gripping member is made to coincide with the axial center of the striking member, and the frictional sliding distance between the striking member and the gripping member can be taken over almost the entire length of the gripping member, so that the contact surface between the two It is possible to obtain a dry firing prevention device that keeps the pressure low, has little wear, and has a long life. In addition, in the present invention, since the protrusion for aligning the axis of the gripping member with the axis of the striking member is formed integrally with the mouth washer, there is no increase in the number of parts and assembly man-hours, and the cost is reduced. This also has the effect of being able to be manufactured in a number of ways.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional side view showing an embodiment of an electric hammer dry striking prevention device according to the present invention. Similarly, FIG. 2 is a longitudinal side view showing a state in which the tool moves forward and the dry striking prevention device is activated. FIG. 3 is a partial longitudinal sectional side view showing an embodiment of the dry hitting prevention device according to the present invention. FIG. 4 is a partially vertical side view showing an example of a conventional dry-hitting prevention device. FIG. 5 is a graph showing the relationship between the amount of penetration of the impactor and the gripping force of the gripping member. In the figure, 1 is a tool, 2 is a retainer, 3 is a front cover, 4 is a gripping member, 5 is a mouth washer, 5a is a projection, 6 is a cylinder case, 7 is a striker, and 8 is a piston.

Claims (1)

[Scope of utility model registration request] This is a striking tool that uses the reciprocating motion of a piston to drive a striker through the air to strike the tool, and when the tool is separated from the workpiece, the tool struck by the striker is limited. movable in the axial direction,
When the striker moves in the direction of the tool following this,
It has a cylindrical gripping member made of an elastic material that fits and grips the outer periphery of the striker, and the cylindrical gripping member is held in the cylinder case by a cylinder case that holds the striker so as to be able to reciprocate and a mouth washer. The impact tool is characterized in that the mouth washer is integrally formed with a protrusion that fits into the inner surface of the gripping member and holds the axis of the gripping member in a concentric position with the axis of the striker. Dry shot prevention device.