JPH0428643Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a coupling structure between a mandrel and a mandrel holder used in hot extrusion pipe making machines and the like.

[Prior Art] In hot extrusion pipe manufacturing, as shown in FIG. 3, a die 3 is fixed in a die holder 2 set on the outlet side of a container 1 by a die backer 4. The hollow bitlet 5 housed in the container 1 has a mandrel 6 inserted therein, and is pressed from behind by a stem 8 via a dummy block 7, thereby forming an annular intermediate between the die 3 and the mandrel 6. The tube 9 is extruded forward from the tube 9.

The mandrel 6 is connected to the tip of the mandrel holder 10, and the connection is usually performed using an intermediate threaded joint 11. This provides compatibility between the mandrel 6 and the mandrel holder 10,
This is to reduce the cost of the expensive mandrel 6 made of high-grade tool steel.

That is, the outer diameter of the mandrel holder 10 is changed according to the outer diameter of the hollow billet 5. On the other hand, even if the mandrel 6 has the same outer diameter as the hollow billet 5, if the inner diameter of the tube 9 changes, the outer diameter of the mandrel 6 is changed to correspond to the inner diameter. In the case where the mandrel 6 is directly connected to the mandrel holder 10, it is necessary to prepare multiple types of mandrels with the same outer diameter just to connect the joint, but an intermediate threaded joint is required between the mandrel 6 and the mandrel holder 10. 11, the mandrel holder 10
Even if the mandrel 6 changes, if the required outer diameter is the same, the same mandrel 6 can be used, and the cost can be reduced.

A conventional coupling structure using this intermediate threaded joint 11 usually has a stem 8 as shown in FIG.
Inside, the proximal end of the intermediate threaded joint 11 is fitted into the distal end of the mandrel holder 10 by screw connection, and the mandrel 6 is fitted onto the distal end of the intermediate threaded joint 11.
The proximal end of the tube is fitted into the body by screw connection. From a work point of view, the directions of the screws are the same.

[Problem that the invention attempts to solve]

However, when hot-extruding tubes are used to continuously extrude a plurality of tubes of the same size, depending on the condition of the mandrel, such as bending, wear, or flaws, the mandrel may be replaced with another mandrel of the same size. At this time, the fourth
In the conventional coupling structure shown in the figure, loosening may occur between the intermediate threaded joint 11 and the mandrel holder 10 when the mandrel is removed.

Since this loosening is hidden in the stem 8 and cannot be seen visually, it is often left unattended, resulting in a decrease in the dimensional accuracy of the tube, or in the case of extruding a tube with external fins, causing the tube to become twisted. When this torsion increases the loosening of the intermediate threaded joint 11, it may not be able to withstand the pulling force when the mandrel is pulled out, and the threads may break, making it impossible to pull out the mandrel.

Furthermore, from the viewpoint of workability, the coupling structure between the mandrel and the mandrel holder must be such that the mandrel and the intermediate threaded joint can be easily attached and detached.

An object of the present invention is to provide a coupling structure between a mandrel and a mandrel holder that prevents the intermediate threaded joint from loosening without making it difficult to attach and detach the mandrel and the intermediate threaded joint.

[Means for solving problems]

FIG. 1 is a longitudinal sectional side view showing an example of a joint structure embodying the present invention, and FIGS. 2A to 2C are structural explanatory diagrams of various pieces used in the joint structure of FIG. 1.

To explain the features of the coupling structure of the present invention with reference to both figures, the tip of the mandrel holder 10, into which the intermediate threaded joint 11 is screwed, screws the first bush 13 coaxially with the mandrel holder 10. . The first bush 13 has a square hole 15 in the central axis direction, as shown in FIG. 2A.

Intermediate threaded joint 1 that screws the mandrel onto the tip
1 has a through hole 17 in the direction of its central axis, and a second bush 18 is screwed coaxially with the intermediate threaded joint 11. The second bushing 18 has a square hole 20 in the central axis direction, as shown in FIG. 2B.

A pin 21 is engaged between the first bush 13 and the second bush 18;
As shown in FIG.
and has.

The first bushing 13 and the second bushing 18 are screwed together in a direction opposite to the direction in which the mandrel and the mandrel holder 10 are screwed together.
Or they are in the same direction but have different pitches.

In addition, in the connection structure of the present invention, the square hole is a hole that prevents the shaft body fitted into the square hole from moving in the circumferential direction and only allows movement in the axial direction, as shown in Fig. 2A. In addition to polygons such as this, star shapes as shown in FIG. 2B, they also include grooved round holes.

[Effect]

When screwing the mandrel into the intermediate threaded joint 11, the intermediate threaded joint 11 is attached to the mandrel holder 10.
It is tightly tightened and will not come loose.

When removing the mandrel from the intermediate threaded joint 11, the intermediate threaded joint 11 tries to loosen with respect to the mandrel holder 10, but the rotational force is
It is transmitted to the first bush 13 via the bush 18 and pin 21. The first bushing 13 and the second bushing 18 are threaded in the opposite direction to the threading of the mandrel and the mandrel holder 10, or in the same direction but with different pitches, so that the bushings 13 and 18 can be rotated. Therefore, the intermediate threaded joint 11 will not loosen.

When removing the intermediate threaded joint 11, remove the pin 21.
Remove. As a result, the intermediate threaded joint 11 is edged against the mandrel holder 10, and the intermediate threaded joint 11 is easily loosened.

〔Example〕

As an embodiment of the present invention, the connection structure shown in FIG.
This will be explained in detail with reference to the drawings.

Mandrel holder 1 inserted into stem 8
A female threaded portion 12 for screwing an intermediate threaded joint 11 is formed at the tip of the 0, and a first bushing 13 is screwed coaxially with the mandrel holder 10 at its bottom. This ring-shaped first bushing 13 has a male threaded portion 1 for screwing onto the mandrel holder 10, as shown in FIG.
4 on the outer periphery, and a square hole 15 in the axial direction at the center of the inside. This square hole 15 has a hexagonal shape.

The intermediate threaded joint 11 has its tail end screwed onto the male threaded part 12 of the mandrel holder 10, while
It has a female threaded portion 16 at its tip for screwing a mandrel, and furthermore, a through hole 17 is provided in the direction of the central axis following this female threaded portion 16. Further, a second bushing 18 is screwed onto the tail end coaxially with the through hole 17. This second bushing 18 is ring-shaped like the first bushing 13, and as shown in FIG.
It has a male screw part 19 on the outer periphery for screwing into the main body 1, and has a square hole 20 in the axial direction at the center of the inner side.
This square hole 20 is star-shaped.

First bushing 13 and second bushing 18
As shown in FIG. 2C, the pin 21 to be engaged has a hexagonal first corner shaft portion 22 at the tail end, a star-shaped second corner shaft portion 23 in front of the hexagonal first corner shaft portion 22, The first square shaft part 22 is fitted into the square hole 15 of the first bushing 13, the second square shaft part 23 is fitted into the square hole 20 of the second bush 18, and the through hole 1 of the intermediate threaded joint 11 is fitted.
It is housed within 7. Reference numeral 24 denotes a female threaded portion provided at the tip of the pin 21 for mounting an attachment/detachment jig.

Then, the intermediate threaded joint 11 is attached to the mandrel holder 10 with a right-handed thread, and the mandrel is attached to the intermediate threaded joint 11.
When screwed on with a right-hand thread, the first bushing 13
The second bush 18 is screwed onto the mandrel holder 10 and the intermediate threaded joint 11 with left-hand threads or right-hand threads with different pitches.

In the connection structure shown in FIG. 1, when attaching the mandrel, the tail end of the mandrel is screwed into the female threaded portion 16 of the intermediate threaded joint 11 with a right-handed thread. This tightening causes a rotational force to act on the intermediate threaded joint 11, but since this rotational force acts in the direction of tightening the intermediate threaded joint 11, it does not cause loosening.

When removing the mandrel, use intermediate threaded joint 1.
1 receives a counterclockwise force against the mandrel holder 10. The rotational force is transmitted from the second bushing 18 to the first bushing 13 via the pin 21. First bush 13 and second bush 1
8 are rotated as one unit by the pin 21, and have left-handed threads or right-handed threads with different pitches, so they do not actually rotate even when subjected to the above-mentioned counterclockwise force. As a result, the pin 21 is prevented from rotating, and the second bush 18 is prevented from rotating, thereby preventing the intermediate threaded joint 11 from loosening.

From the mandrel holder 10 to the intermediate threaded joint 11
To remove the pin 21 from the female threaded portion 16 in the axial direction. This cuts the edge between the first bushing 13 and the second bushing 18, so if you loosen the intermediate threaded joint 11 counterclockwise,
The intermediate threaded joint 11 is removed from the mandrel holder 10.

When attaching the intermediate threaded joint 11 to the mandrel holder 10, the pin 21 is inserted after the intermediate threaded joint 11 is screwed.

At this time, unless the rotational position of the square hole 15 and the rotational position of the square hole 20 match, the pin 21 will not be inserted. In order to facilitate insertion of the pin 21, it is recommended that at least one of the square holes 15 and 20 has a fine pitch. This is why the square hole 20 has a star shape in the coupling structure shown in FIG.

In the connection structure shown in FIG. 1, the mandrel and the intermediate threaded joint are screwed together with a right-handed thread, but a left-handed thread may be used if there is no problem with the work.
Further, although the mandrel and the intermediate threaded joint are both fitted inside the intermediate threaded joint and the mandrel holder, it is also possible to have a structure in which one or both of them are fitted externally.

[Effect of idea]

As is clear from the above explanation, the coupling structure of the present invention not only prevents the intermediate threaded joint from loosening when the mandrel is removed and ensures stable pipe manufacturing work, but also allows the mandrel and intermediate threaded joint to be connected as before. Since it can be attached and detached using screws in the same direction, there is no confusion for the operator, and since loosening can be prevented by simply inserting and removing pins, the work is not complicated, and the overall process is simple, stable, and smooth. This makes pipe work possible.

[Brief explanation of drawings]

Fig. 1 is a vertical side view showing an example of a joint structure in which the present invention is implemented, Fig. 2 A to C are structural explanatory diagrams of various pieces used in the structure shown in Fig. 1, and Fig. 3 shows a hot extrusion pipe manufacturing. FIG. 4 is a longitudinal sectional side view showing a conventional coupling structure. In the diagram, 1... Container, 3... Dice, 5...
Hollow billet, 6... Mandrel, 8... Stem, 10... Mandrel holder, 11... Intermediate threaded joint, 13, 18... Bush, 15, 20
...Square hole, 17...Through hole, 21...Pin, 2
2, 23... Square shaft part.

Claims (1)

[Scope of utility model registration request] In coupling the mandrel 6 and the mandrel holder 10, in which the tail end of the mandrel 6 is coaxially screwed to the tip of the mandrel holder 10 via an intermediate threaded joint 11, the tip of the mandrel holder 10 has a square hole 15 in the direction of the central axis. First button 13
The intermediate screw joint 11 is provided with a through hole 17 in the central axis direction, and a second bush 18 having a square hole 20 in the central axis direction is coaxially screwed, and the first bush 13 and the second bush 18 are coaxially screwed together. The through hole 17 is inserted between the second bush 18 and the first square shaft part 22 is fitted into the square hole 15 of the first bush 13 and the square hole 20 of the second bush 18 is fitted. The pin 21 having the second square shaft portion 23 is engaged, and the first bushing 13 and the second bushing 18 are screwed together in a direction opposite to the direction in which the mandrel 6 and the intermediate threaded joint 11 are screwed together. , or a combined structure of a mandrel and a mandrel holder characterized by having different pitches in the same direction.