JP2573528Y2 - Universal joint for small diameter pipe thrusters - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a universal joint of a small-diameter pipe propulsion machine having an improved torque transmission structure.

[0002]

2. Description of the Related Art When a small-diameter pipe is buried in the ground using a conventional small-diameter pipe propulsion machine, a small-diameter pipe propulsion machine b installed in a starting shaft a as shown in FIG. The small-diameter pipe d equipped with the conduit c is propelled into the ground. A cutter head e is provided at the tip of the front pipe c, and the earth and sand excavated by the cutter head e is carried out by a screw conveyor f provided in a small-diameter pipe d. The drive device g of the small-diameter pipe propulsion device b is connected via a screw shaft h of a screw conveyor f, and the cutter head e is rotated by the drive device g via the screw shaft h. .

The screw conveyor f is divided for each unit length of the small-diameter pipe d and is connected when the small-diameter pipe d is added. Therefore, torque transmission between the screw shafts h is performed. Are connected by a universal joint i as shown in FIGS. The universal joint i has a structure in which a fitting portion k of a joint body is fitted into a hexagonal fitting hole j formed on the screw shaft h side and a bolt m is passed between the two, and torque is transmitted. Is performed using a two-plane width.

[0004]

In the above conventional universal joint A devised to solve the above, in the case of performing the torque transmission in the presence of swing angle theta ₀ between before and after the screw axis h as shown in (b) of FIG. 4, screw The fitting hole j on the shaft h side is shown in FIG.
The torque is transmitted while repeating the deformation indicated by the solid line and the imaginary line, and as a result, the top of the hexagon becomes a notch, and stress concentrates on this notch portion n as shown in FIG. There was a problem that this part was easily damaged.

[0005] In addition, since the torque is transmitted by point contact, the surface pressure on the transmission surface is significantly increased, and the transmission surface is depressed early, and there is a problem that the life of the transmission surface is short and short. The present invention has been made to solve such a problem, and an object of the invention is to provide a universal joint for a small-diameter pipe propulsion machine whose life is greatly improved by improving a torque transmission structure.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a screw conveyor provided in a small-diameter pipe following a leading pipe. In the small-diameter pipe propulsion machine designed to be carried out by a screw, a universal joint for connecting the screw shafts of the screw conveyor is provided with alternating peaks and valleys in the circumferential direction at the ends of the screw shafts to be connected to each other. A fitting portion is formed, and these peaks and valleys are fitted to each other, and a reaction force receiving shaft is inserted through the center of each fitting portion. Are connected.

[0007]

According to the above construction, torque transmission is performed between the crests and the valleys fitted to each other, so that the torque transmission surfaces do not come into surface contact and the surface pressure does not become abnormally high, and the stress concentration does not occur. Therefore, it is possible to prevent the durability of the fitting portion from being reduced.

[0008]

One embodiment of the present invention will be described in detail with reference to the drawings shown in FIG. FIG. 6 is a cross-sectional view of a universal joint used for a screw conveyor of a small-diameter pipe propulsion machine.
FIG. 7 is an exploded perspective view of the same, in which 1 and 2 indicate screw shafts. Fitting portions 1a and 2a are formed at ends of the screw shafts 1 and 2 to fit each other.
The fitting portions 1a and 2a are, as shown in FIG.
b and the valleys 1c and 2c are formed alternately in the circumferential direction. The valley 2c of the other fitting part 2a is provided on the peak 1b of the one fitting part 1a, and the one fitting part 1a. The peak 2b of the other fitting portion 2a is fitted to the valley portion 1c of the other, and the outer diameter of each fitting portion 1a, 2a is the screw shaft 1,
2 is smaller than the outer diameter of the fitting portion 1 having a smaller diameter.
The cylindrical collar 3 is fitted to a and 2a.

Dust seals 4 are provided on the inner peripheral surfaces of both ends of the collar 3 so as to prevent intrusion of earth and sand and to prevent lubricant such as grease sealed in the fitting portions 1a and 2a from leaking. And each fitting part 1
The inner diameters of a and 2a are also smaller than the inner diameters of the screw shafts 1 and 2, and a hollow reaction force receiving shaft 5 whose outer diameter is sufficiently smaller than the inner diameter is inserted through the inner diameter of the small diameter.

[0010] Both ends of the reaction force receiving shaft 5 project into the screw shafts 1 and 2, and a reaction force receiving ring 6 is provided at both ends.
Are fitted and nuts 7 are screwed to both ends of the reaction force receiving shaft 5.
To prevent it from slipping out. The reaction force receiving ring 6 has a spherical portion 6a.
Steps 1d, 2d formed on inner peripheral portions of the fitting portions 1a, 2a
The spherical portion 6a of the reaction force receiving ring 6 and the spherical bush 8 are pressed against the spherical bush 8
Is provided with a seal 9 for preventing the lubricant sealed in the fitting portions 1a, 2a from leaking.

Next, the operation will be described. The torque applied to one screw shaft 1 is transmitted to the other screw shaft 2 via the fitting portions 1a, 2a. In addition, when the other screw shaft 2 is swung with respect to one screw shaft 1 as shown in FIG. 8 by controlling the direction of the leading conduit, a swing angle θ ₀ is generated at the center of each screw shaft 1, 2. However, since the spherical portion 6a of the reaction force receiving ring 6 provided at both ends of the reaction force receiving shaft 5 slides and absorbs the torque, the torque transmission is performed in the same manner as in the case where the centers of the screw shafts 1 and 2 coincide. Can be performed.

On the other hand, each fitting portion 1a, 2a is
By engaging with each other as valleys 1c and 2c,
The concentration of stress can be prevented. Next, the reason will be described. As shown in FIG. 9 (a), when the fitting portions 1a and 2a are formed of a convex portion and a concave portion and mesh with each other, concentrated stress is generated at the root A of the convex portion. As a result, the strength of this portion is significantly reduced. Therefore, as in the present invention, the fitting portions 1a, 2a are formed by the peak portions 1b, 2b and the valley portions 1c, 2c and are engaged with each other. At this time, when the length of the torque transmission surface is S, the height is h, and the transmission torque is N, the fitting portion 1
When a and 2a are made into peaks 1b and 2b and valleys 1c and 2c,
Transmission torque N as shown in (b) of FIG. 9 is a component force to the torque transmission faces f _'T and f _P. The length S ′ of the torque transmitting surface is S ′ = S / sin θ, and the transmitted torque is N ′ = f _T /
It becomes S. And the surface pressure

[0013]

(Equation 1)

Thus, the surface pressures of σ90 ° and σθ become equal. Note that f _P is a tensile force generated on the reaction force receiving shaft 5, and does not occur when the fitting portions 1a and 2a are formed in an uneven shape. That is, the fitting portions 1a, 2a are formed into the peak portions 1b, 2b and the valley portions 1c,
In the case of 2c, the surface pressure generated on the torque transmitting surface is equal and the angle of the stress concentration portion A becomes large, so that the concentrated stress can be reduced.

[0015]

According to the invention, as described in detail above, a fitting portion composed of a peak portion and a valley portion is formed at an end of a screw shaft connected to each other, and these fitting portions are fitted together. Since the fitting portions are connected via a reaction force receiving shaft, the torque transmission surface at the time of torque transmission is in surface contact, and the torque is transmitted. It can be significantly reduced. As a result, the torque transmission surface does not come off or peel off early,
The service life of the universal joint can be greatly improved, and stress concentration can be reduced, so that strength and durability due to stress concentration can be prevented from lowering. In addition, since the swing angle can be made large, the direction can be easily corrected.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a conventional small-diameter pipe propulsion device.

FIG. 2A is a longitudinal sectional view of a conventional universal joint. FIG. 2B is a sectional view taken along line AA of FIG.

FIG. 3A is a cross-sectional view of a conventional universal joint. (B) It is sectional drawing which follows the BB line | wire of FIG.3 (a).

FIG. 4 is an operation explanatory view of a conventional universal joint.

FIG. 5A is an explanatory view showing stress strain of a conventional universal joint. (B) It is explanatory drawing which shows the stress concentration of the conventional universal joint.

FIG. 6 is a longitudinal sectional view of a universal joint according to an embodiment of the present invention.

FIG. 7 is an exploded perspective view of a universal joint according to an embodiment of the present invention.

FIG. 8 is an operation explanatory view of a universal joint according to an embodiment of the present invention.

FIG. 9A is an explanatory diagram showing the surface pressure of the torque transmitting surface when the fitting portion is made uneven. (B) It is explanatory drawing which shows the surface pressure of the torque transmission surface of the fitting part which comprised the fitting part by the peak part and the trough.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Screw shaft 1a Fitting part 1b Crest part 1c Valley part 2 Screw shaft 2a Fitting part 2b Peak part 2c Valley part 5 Reaction force receiving shaft

Claims (1)

(57) [Scope of request for utility model registration] 1. A small-diameter pipe propulsion device according to claim 1, wherein the earth and sand excavated by a cutter head provided at the tip of the leading pipe are carried out by a screw conveyor provided in a small-diameter pipe following the leading pipe. A universal joint for connecting the screw shafts 1 and 2 of the conveyor is provided with a fitting portion having, at the ends of the screw shafts 1 and 2 to be connected to each other, ridges 1b, 2b and valleys 1c, 2c alternately arranged in the circumferential direction. 1a, 2a, and these peaks 1b, 2b
And the valleys 1c, 2c are fitted to each other, and
a, a universal joint of a small-diameter pipe propulsion machine, in which a reaction receiving shaft 5 is inserted through the central portion of each of the screw shafts 1 and 2 to connect the screw shafts 1 and 2 via the reaction receiving shaft 5. .