JPH0626746Y2 - Screw structure of rod joints of rotary percussion and rotary drill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a screw for a rod joint of a rotary percussion and a rotary drill, in which a screw formed at an end is screwed to a screw such as a coupling to extend the screw. The present invention relates to a screw structure capable of strengthening a stress concentrating portion of a rod joint, which constantly breaks when the portion loosens.

(Prior Art) When extending the tip bit of a rotary percussion and a rotary drill, a rod joint having threads formed at both ends of a hollow tube is extended by connecting a coupling or the like.

The thread forming portion of a conventional rod joint has a male thread formed on a coupling and the like and a female thread formed on the inner surface of the rod joint in a normal thread shape. Further, these screws have a parallel thread or a taper thread shape such as a taper 1/16 to be used for connecting and fixing, and those having a good waterproof effect are required. or,
Japanese Unexamined Patent Publication No. 61-24821 discloses the use of a screw formed in a joint portion with an inclination.
The effect is not sufficient because the inclination of the screw cannot be increased in a rod joint with a thin wall thickness. Further, there is a problem with the above-mentioned taper screw.

(Problems to be Solved by the Invention) However, the wall thickness of this hollow tube is limited, and therefore the wall thickness of the screw bottom is particularly thin. Also, the extended rod joint may loosen the threaded portion due to impact. With this conventional rod joint, if the threaded portion loosens during use, the male threaded portion from the screw starting end of the coupling tip to about the third crest Unbalanced load of strong impact force is concentrated on the screw thread of the rod joint, and as a result, it breaks and breaks at the thread bottom part of the end of the female thread of the rod joint extended by screwing with this male screw, and therefore the strength of the thread forming part of the rod joint is increased. There was a problem that it had to be large.

Also, a screw formed with a taper screw such as a taper 1/16 has a good waterproof property but is easily loosened, and once it is loose a little, it becomes impossible to work. Therefore, even if the screw is loose, the impact force is correctly transmitted. There was a problem in that it had to be a screw structure that could be used.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned conventional problems. Even when the rod joint of the rotary percussion or the rotary drill is loosened during the operation, the impact force, the load, etc. are reduced. (EN) Provided is a threaded structure for a rod joint of a rotary percussion and a rotary drill, which allows the rod joint to be used uniformly without breaking and damaging the threads.

The gist of the idea is that, in rotary percussion and rotary drill rod joints in which the female thread formed at the end is screwed to a male thread such as a coupling to extend, the top of the thread of the male thread is cut out and outside the male thread forming section. The diameter gradually increases toward the end so that the diameter becomes the minimum at the beginning of the male thread, and the depth of the valley of the female thread of the rod joint screwed to the male thread is adjusted to the height of each thread of the male thread. In addition, the thread structure of the rod joint of the rotary percussion and the rotary drill is characterized in that the root diameter of the internal thread forming portion is gradually reduced toward the terminal end so that the internal thread starting end has the maximum diameter.

(Operation) In the thread structure of the rod joint of the present invention, the outer diameter of the male thread forming portion such as the coupling is formed in a taper shape, and the depth of the root of the female thread section of the rod joint is adjusted to the height of each thread of the male thread. By making the depth deeper, the root diameter of the female screw forming portion is tapered.

The wall thickness of the trough portion of the female screw end portion of the rod joint thus configured is thicker than the wall thickness of the trough portion on the start end side, and the cross-sectional area increases, so that the strength against external force is increased. In addition, the depth of the trough of the internal thread is the shallowest at the end of the screw and the deepest at the beginning, so when the male thread of the coupling is screwed onto this, the height of the thread ridge at the end of the internal thread is It is the smallest. The height of this hook gradually increases toward the end of the internal thread, and the external force is applied according to the height of this hook, and the impact force, which tends to concentrate on the end of the internal thread, is evenly distributed to each screw, and It has become possible to prevent product damage and prolong the product life.

Also, even if the screw part loosens during the work, the ratio of the height of the hooks of each screw does not change, so each screw always receives and transmits an equal external force, so the work can be continued without interruption. You can

(Example) Hereinafter, an example of the present invention will be described.

FIGS. 1 to 4 show a taper outer diameter of a male thread portion of a parallel screw, and FIG. 1 is an explanatory view of a portion where a rod joint is screwed to a coupling.

In the figure, (1) is a rod joint, (2) is a coupling, (3) is a female thread forming portion of the rod joint (1), (4) is a female screw starting end portion, (5) is a female thread forming portion root diameter, (6 ) Is the thread, (7) is the end of the female thread,
(8) is a male screw forming portion, (9) is an outer diameter of the male screw forming portion, (10) is a male screw starting end portion, (11) is a bit, and (12) is a sliding bearing on the rotary percussion side.

According to the structure of this embodiment, it is possible to extend the product life by several times as compared with the conventional structure.

Although the embodiment of the present invention has been described above, the specific configuration of the present invention is not limited to this embodiment.

For example, although the screw is formed as a parallel screw, the screw is not limited to this and may be formed as a taper screw having a taper of about 1/40.

Incidentally, FIG. 6 shows a conventional threaded portion, (13) is a screw thread on which an impact force mainly acts, and (14) is a damage which occurs steadily.

(Effect of the Invention) As described above, according to the present invention, the strength of the thread forming portion of the rod joint used in the rotary percussion and the rotary drill can be increased. Further, since the impact force is evenly distributed to each screw even if the screw is loosened, the rod joint is not damaged during the work.

In addition, since the strength can be increased without changing the outer diameter of the rod joint, it can be used in conventional equipment and is very economical.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a screw structure of a rod joint according to an embodiment of the present invention, FIG. 2 is a sectional view of an essential part of a rod joint, FIG. 3 is a sectional view of an essential part of a coupling, and FIG. FIG. 5 is an explanatory view showing a state, FIG. 5 is a sectional view showing a screw structure of a rod joint having a taper screw shape, and FIG. 6 is an explanatory view showing a screw structure of a conventional rod joint. (1): Rod joint, (2): Coupling (3): Female thread forming part, (4): Female thread starting end part (5): Female thread forming part root diameter, (6): Thread (7): Female thread end Part, (8): Male screw forming part (9): External diameter of male screw forming part, (10): Male screw starting end

Claims (1)

[Scope of utility model registration request] 1. A rod joint for a rotary percussion and a rotary drill, wherein a female screw formed at an end is screwed to a male screw such as a coupling to extend, and a male thread forming portion is formed by notching the top of the thread of the male screw. The outer diameter is gradually widened toward the end so that it becomes the minimum diameter at the beginning of the male thread, and the depth of the valley of the female thread of the rod joint screwed to the male thread is the height of each thread of the male thread. In accordance with the above, the thread structure of the rod joint of the rotary percussion and the rotary drill is characterized in that the root diameter of the internal thread forming portion is gradually reduced toward the terminal end so that the internal thread starting end has the maximum diameter.