JPS6347364Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a plug mounting structure for a drilling machine used for manufacturing seamless steel pipes, and in particular, a plug mounting structure for a core circulation type, so-called versatility type drilling machine. Regarding.

In conventional common drilling machines, the core bar is extracted from the material each time a single hole is drilled into the material. The plug attached to the tip of the core bar causes a shock when the core bar is removed, so it must be removed from the core bar immediately after drilling, and the core bar must be moved back a distance at least equivalent to the length of the material. Ru.

On the other hand, a versatility type drilling machine, as its name suggests, recycles a core metal (bar). That is, a plurality of core metals are prepared in advance, the material after drilling is discharged to the side of the line together with the core metal, another core metal is attached to the drilling machine, and the material and the core metal are separated outside the line.
This is to prepare for the reuse of the core metal. Therefore, in this drilling machine, there is no need to move the core metal back significantly, and the drilling pitch is raised, so that manufacturing efficiency is said to be significantly improved.

However, this drilling machine also has major weaknesses. It is the plug fitting structure. Many structures have already been proposed for the plug attachment part, but all of them are based on the premise of conventional general drilling machines. Bad,
This causes problems such as poor operability.

That is, in conventional drilling machines, the plug is removed every time a hole is drilled, as described above, so the structure of the attachment part is designed with the main focus on ease of detachment of the plug. However, with the versatility type, the material and core are separated outside the line (specifically, the core is pulled out to the rear of the material), so there is no need to remove the plug at the tip of the core.
The core metal is used repeatedly with the plug attached.
For this reason, in a plug attachment structure designed with ease of removal in mind, the plug may come off by mistake or require more external force than necessary to hold the plug. However, on the other hand, since it is required to replace the plug every few uses, it is also necessary that the plug can be easily removed at that time.

The present invention provides a plug attachment structure suitable for a versatility type drilling machine, in which the plug is always securely fixed to the core metal, and the plug can be easily removed when necessary.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

In FIG. 1, reference numeral 1 denotes the tip of the metal core, which has a two-stage structure of a small diameter part and a large diameter part. A plug 2 is externally fitted into the small diameter portion, and a radial through hole 3 is cut therein. A steel ball 4 that prevents the plug 2 from separating from the core metal is housed in the through hole 3 so as to be retractable from the outer peripheral surface. This steel ball 4 is configured so that a portion thereof appears from the outer circumferential surface of the core metal in a state in which it is pushed out to the outermost side, and does not move outward beyond this position. The inner peripheral surface of the plug 2 is provided with a recess 5 into which a steel ball 4 is fitted.

The recess 5 has a larger radius of curvature than the steel ball 4 (r
>R), and the center position should be slightly shifted outward and forward. The reason for this is that when the plug 2 is pushed backwards during drilling and the force (thrust force) is transmitted to the rod 7 (described later) through the steel ball 4, the watertightness between the rod 7 and the core bar deteriorates. This is to prevent the recess 5 from compressing the steel ball 4 during drilling, since this may also cause problems such as damaging the rod 7.

The small diameter portion of the metal core is also provided with a lumen 6 that is coaxial with the metal core. A rod 7 for controlling the appearance and retraction of the steel ball 4 is slidably and watertightly inserted into the inner cavity 6 communicating with the hole 3. This rod 7 has a tapered part 7b at the tip of its large-diameter parallel body part 7a and a small-diameter part 7c following this, and the steel ball 4 is pushed out to the outermost side by the large-diameter parallel body part 7a at the forward limit. The steel ball 4 is supported in a state where it is completely immersed in the core metal by the small diameter portion 7c at the retraction limit (see Fig. 2).

The rod 7 also has a piston 8 at its rear end, which can be slidably and watertightly inserted into a second large-diameter lumen 9 formed in the large-diameter portion of the core metal and continuous with the lumen 6. Insert. This piston 8 is constantly pressed in the direction of the tip of the core metal by a spring 10 provided at the rear thereof, and positions the rod 7 at its forward movement limit.
is constructed so that it remains. Reference numeral 13 denotes a pressure introduction port for supplying hydraulic pressure to the gap 12, and the valve body 15 (steel ball) is brought into pressure contact with the valve body 15 (steel ball) from the inside by a spring 14, so that it is self-closed.

The operation of the plug attachment structure having the above configuration is as follows.

To attach the plug 2, hydraulic pressure is supplied into the gap 12 from the pressure introduction port 13, the piston 8 is moved rearward against the pressing force of the spring 10, and the rod 7 is moved backward. FIG. 2 shows the state when the rod 7 has moved to the backward limit. By moving the rod 7 to its retraction limit, the steel ball 4 sinks into the core metal, allowing the plug 2 to be inserted. Note that even if the rod 7 moves backward, the steel ball 4 is supported by the small diameter portion 7c of the rod 7 and will not fall into the inner cavity 6.

When the plug 2 is inserted into the small diameter portion of the core metal, it pushes the valve body 15 of the pressure introduction port 13. By pushing the valve body 15, the liquid pressure in the gap 12 is released from the pressure introduction port 13, and at the same time the piston 8 is released from the spring 10.
The rod 7 is pushed back forward by the force of the rod 7 and moves forward. When the rod 7 moves forward, its tapered portion 7
The steel ball 4 is pushed outward by b and fits into the recess 5 of the plug 2. When the rod 7 moves to its forward limit, the steel ball 4 is supported by its large-diameter parallel body 7a. Once the steel ball 4 is supported by the large-diameter parallel body 7a, the steel ball 4 will not sink into the core metal unless hydraulic pressure is supplied to the cavity 12, so that the steel ball 4 will not sink into the core without any external force. It becomes possible to keep the plug 2 on the gold tip 1, and there is no risk of the plug 2 accidentally coming off.

When removing the plug 2, as in the case of installing the plug 2, open the air gap 12 from the pressure introduction port 13.
All you have to do is supply hydraulic pressure inside. By supplying hydraulic pressure to the gap 12, the rod 7 retreats and the steel ball 4
is immersed into the core metal, and the restraint of the plug 2 is released.

Note that only one steel ball 4 is shown in this embodiment. Although the purpose of fixing and holding the plug 2 can be achieved by this alone, it is actually preferable to provide two or more at equal intervals in the circumferential direction of the core metal.

It is also possible to provide a plurality of pressure introduction ports 12 in the circumferential direction of the core metal.

Further, although hydraulic pressure is used in this embodiment to move the piston 8 backward, it is also possible to use gas pressure such as air pressure. When using gas pressure, the rod 7 (including the piston 8) is connected to the inner cavity 6,
9 must be an airtight fit.

Furthermore, the rod 7 may be provided with a flow path for sending cooling water to the plug 2.

As is clear from the above explanation, in the plug mounting structure of the present invention, the plug 2 is attached to the tip 1 of the core metal by the action of the spring 10, the large-diameter parallel body 7a of the rod 7, and the steel ball 4. Not only is no external force or effort needed to securely hold the plug 2, but there is also no risk of the plug 2 being held securely falling off by mistake. Moreover, when installing or removing the plug 2, the restraint of the plug 2 can be easily released, so even though the plug 2 is firmly connected, it is easy to replace. A device for clamping the plug 2 is also not required.
Therefore, the plug attachment structure of the present invention can be used in a versatility type drilling machine that recirculates the core metal with the plug 2 attached, resulting in extremely high workability and safety.

In addition, in the plug mounting structure of the present invention, since the rotatable steel ball 4 is used as the locking piece of the plug 2, the thrust force applied to the locking piece is effectively dispersed, and the locking piece etc. Not only can damage to the steel ball 4 be prevented, but depending on the positional relationship between the steel ball 4 and the recess 5, it is also possible to virtually prevent thrust force from being applied to the steel ball 4.

Furthermore, since the core metal also serves as the cylinder tube of the rod 7 (including the piston 8), and the entire holding mechanism for the plug 2 is housed within this core metal, the structure is simple and compact, and therefore costs are reduced. It is also excellent.

Furthermore, even when the rod 7 is at its forward movement limit, a gap 12 is left in front of the piston 8 so that full pressure is always applied to the front of the piston 8, so that the initial movement when the rod 7 moves backward is facilitated. , the time required to attach and detach the plug 2 is further reduced.

[Brief explanation of drawings]

Figures 1 and 2 show an example of the structure of the plug mounting part in which the present invention is implemented. Figure 1 shows the plug in a restrained state, and Figure 2 shows the plug in an unrestricted state. . In the figure, 1: Core metal tip, 2: Plug, 3: Through hole, 4: Steel ball, 5: Recess, 6, 9: Bore, 7: Rod, 8: Piston, 10: Spring, 12:
Gap, 13: Pressure introduction port.

Claims (1)

[Scope of utility model registration request] A plug 2 having a recess 5 formed on the inner circumferential surface is fitted onto the small diameter portion of the core metal tip 1 having a small inner and outer diameter, and engages with the recess 5 to prevent the plug 2 from separating from the core metal. A preventing steel ball 4 is provided so as to be retractable from the outer peripheral surface of the small diameter part, and in the inner cavity 6 of the small diameter part, a small diameter part 7c, a tapered part 7b, and a large diameter parallel body part 7a are arranged in order from the tip.
A rod 7 for controlling the appearance and retraction of the steel ball 4 is formed at the rear end of the large-diameter parallel body portion 7a and has a piston 8 that is watertightly fitted into the inner cavity 9 of the large-diameter portion of the tip end portion 1 of the core metal. , a spring 10 disposed on the rear surface of the piston 8 is fitted inside to pressurize it toward the tip of the core metal, while a spring 10 is inserted between the piston 8 and the front wall 11 of the large diameter inner cavity of the tip end 1 of the core metal when necessary. A mounting structure for a core circulation type perforated plug, characterized in that a gap 12 is formed for introducing pressure fluid and retracting a piston 8.