JPH0790254B2 - High precision drawn tube manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a drawn tube having high dimensional accuracy.

[Conventional technology and its problems]

Conventionally, drawing tubes that require relatively high dimensional accuracy are
5 or a method as shown in FIG.

The method shown in Fig. 5 is used for pipe materials made of aluminum alloy, etc. 11
During the drawing process by passing it between the die 12 and the plug 13 attached to the tip of the plug rod 14, the trough 16 with a large number of rollers 15 is moved up and down so that the central axis of the pipe material 11 is diced. The drawing process is performed in a state where it is aligned with the central axis of 12. However, even if such a method is adopted, the drawn pipe obtained does not have uneven thickness or bending smaller than a certain degree. This is because the rear end of the pipe material 11 is free, so that the deflection of the rear end side of the pipe material occurs during the drawing process, and the deflection causes uneven thickness and bending. There is also a problem that scratches and dents are likely to occur due to the pipe material coming into contact with rollers and the like.

Further, in the method shown in FIG. 6, a steadying jig 17 is intermittently attached to the plug rod 14, and the pipe 11 is pulled out while the runout is reduced. However, this method requires some clearance between the steadying jig 17 and the inner surface of the pipe material 11, so it is difficult to completely eliminate the runout of the pipe material 11, and the occurrence of uneven thickness and bending to some extent. It cannot be made smaller than this.

Aluminum alloy drawn tubes are generally used for the photoconductor drums of electronic copying machines and the magnetic drums of magnetic storage devices, but these drawn tubes are extremely high in terms of uneven thickness, bending, and roundness. Dimensional accuracy is required and the surface condition must be very good. However, the above-mentioned method cannot manufacture a drawn tube satisfying the requirement. For this reason, conventionally, after the drawing process, the straightening process and the precision cutting process are performed to obtain the required dimensional accuracy and surface condition, which causes a problem that the processing cost is high.

[Means for solving the problem and its action]

The present invention provides a method for manufacturing a high-precision drawn tube that solves the above problems, and the method is attached to the tip of a die 12 and a plug rod 14 as shown in FIG. When a drawn pipe is manufactured by drawing the pipe material 11 between the plug 13 and the plug 13, the rear end of the pipe material 11 is held by the holding means 20 so that the central axis of the pipe material 11 coincides with the central axis C of the die 12. It is characterized in that the drawing process is carried out while holding it. The holding means 20 runs together with the pipe material 11.

By doing this, the center axis of the pipe material can be aligned with the center axis of the die, and the drawing process can be performed with the deflection of the rear end side of the pipe material being prevented, resulting in significantly higher dimensional accuracy than before and in addition scratches and dents on the surface. It will be possible to manufacture drawn tubes without

In the above method, when the plug rod 14 is held near the rear end of the pipe material 11 by the holding means 20 so that the central axis of the plug rod 14 coincides with the central axis C of the die, the plug rod 14 is
It is also possible to prevent a decrease in dimensional accuracy due to the bending of 14.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS.

In FIG. 2, 11 is a pipe material, 12 is a die, and 13 is a plug attached to the tip of a plug rod 14. Further, 21 is a guide rail installed on both sides of the plug rod 14 in parallel with the central axis of the die 12, 22 is a trolley guided by the guide rail 21, and 23 is a pipe member provided on the trolley 22.
A holding mechanism that holds the rear end of 11 on the same axis as the die 12.

The holding mechanism 23, as shown in FIGS.
It has a pair of holding claws 24 inserted at the rear end thereof, and the holding claws 24 are opened and closed by an actuator 25. In this example, the forward and backward movements of the actuator 25a of the actuator 25 are converted into rotational movement by the link 26, the upper arm 27, the rotating shaft 28, and the lower arm 29, and the holding claw 24 is opened and closed. The state of the solid line in Fig. 3 is the actuator.
The actuator 25a of 25 moves forward, the holding claw 24 is expanded, and the pipe material 11
Is being pressed against the inner surface of (the state in which the rear end of the pipe material 11 is held), and when the actuator 25a retracts from this state, the holding claw 24 is narrowed as shown by the dotted line. The holding claw 24 is formed in an arc shape as shown in FIG. 4, and the tube material 11 can be centered by simply pressing it against the inner surface of the tube material 11.

The cart 22 does not have a self-propelled function, and is pulled by the pipe material 11 by a frictional force generated by pressing the holding claw 24 against the inner surface of the pipe material 11 to run. A roller 30 that holds the plug rod 14 on the same axis as the die 12 is provided on the rear surface of the carriage 22. The roller 30 serves to prevent the plug rod 14 from bending and keep the plug 13 in the proper direction.

As shown in Fig. 2, the pipe material is
The rear end of 11 is held on the same axis as the die 12 by the holding mechanism 23, and since the carriage 22 travels together with the rear end of the pipe material 11, the pipe material 11 is stable without any runout on the rear end side. It will be drawn in the state. Therefore, it is possible to manufacture a drawn tube having neither uneven thickness nor bending, a high roundness, and no scratches or dents.

When one pulling process is near the end, the carriage 22 hits a stopper 31 provided on the guide rail 21 and stops. Since the holding claw 24 is merely pressed against the inner surface of the pipe material 11, even if the carriage 22 is stopped, the pipe material 11 travels as it is, and is removed from the holding claw 24 to be drawn to the end.

After one drawing process is completed, the next pipe member is externally inserted from the plug 13 side to the plug rod 14, and the actuator 25 is operated to insert the holding claw 24 at the rear end of the pipe member. In this state, the pipe material is moved backward and the carriage 22 is retracted. When the tip of the pipe material is inserted into the die 12, the same drawing process can be performed again.

Next, the results of manufacturing the aluminum alloy drawn tube by the above method are shown in Table 1 in comparison with those manufactured by the conventional method. In the same table, "outer diameter roundness" is the difference between the maximum outer diameter and the minimum outer diameter, and "bending" is the maximum displacement from a straight line when a straight line is placed along a 300 mm long sample. . The surface roughness of each drawn tube was Rmax 2 μm or less.

As is clear from Table 1, according to the present invention, it is possible to manufacture a drawn tube having extremely higher dimensional accuracy than before, and the drawn tube manufactured in this manner has no scratches or dents and therefore has a surface condition. Very good. Therefore, it can be used as a high precision tube for a photoconductor drum, a magnetic drum or the like of an electronic copying machine without performing straightening and precision cutting, or with a slight surface finish, which is very effective in reducing the processing cost.

Although the holding mechanism has a structure for holding the rear end of the pipe material from the inner surface in the above-described embodiment, the holding mechanism may have a structure for holding the rear end of the pipe material from the outer surface like a normal clamp.

Further, the manufacturing method of the present invention can be applied not only to an aluminum alloy drawn tube but also to a drawn tube made of another metal (for example, iron-based or copper-based).

Further, the manufacturing method of the present invention can be applied not only to the manufacture of a tube having a circular cross section but also to the manufacture of a tube having a non-circular cross section (for example, a square tube, an elliptic tube, etc.).

〔The invention's effect〕

As described above, according to the present invention, the rear end of the pipe material is held on the same axis as the die, and the drawing process is performed in a state in which the shake at the rear end side of the pipe material is eliminated. It is possible to produce a high-precision drawn tube with high roundness and good surface condition without the occurrence of meat or bending.

[Brief description of drawings]

1 is an explanatory view showing the basic concept of the present invention, FIG. 2 is a plan view showing an example of a drawing device for carrying out the manufacturing method of the present invention,
3 and 4 are a plan view and a front view of a bogie portion of the apparatus, and FIGS. 5 and 6 are explanatory views showing a conventional manufacturing method. 11: Pipe material, 12: Die, 13: Plug, 14: Plug rod, 2
0: holding means, C: central axis.

Claims (2)

[Claims] 1. A method for producing a drawn pipe by drawing a pipe material between a die and a plug attached to a tip of a plug rod to perform a drawing process, wherein a rear end of the pipe material has a center axis line of the die. A method for producing a high-precision drawn tube, which is characterized in that the drawing process is performed while holding the drawn tube so as to match the central axis line of 2. The manufacturing method according to claim 1, wherein the plug rod is held near the rear end of the pipe material such that the central axis of the plug rod coincides with the central axis of the die.