JPH0576936A - Elliptical tube straightening device and tube elliptical straightening method using the device - Google Patents

Abstract

(57) [Abstract] [Purpose] To make it possible to correct an ellipse generated in a thin-walled casting pipe with good efficiency and over the entire length of the pipe. [Structure] The casting pipe 2 is horizontally supported by a pair of supporting drive rolls 7 and rotated about its axis, and the straightening roll 13 presses the pipe 2 from above to make the ellipse of the pipe 2 full length. Straighten over. A large amount of pushing is applied to the straightening roll 13 to perform the first stage straightening, and then a small amount of pushing is performed to perform the second stage straightening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tube elliptical straightening apparatus and a tube elliptical straightening method using the apparatus.

[0002]

2. Description of the Related Art Conventionally, as a method for producing a ductile cast iron pipe having a receiving end at one end and an inserting end at the other end, it is general to perform annealing after centrifugally casting the pipe. By the way, when the pipe is cast and annealed in this way, the outer diameter of the pipe may become elliptical, which is not preferable. For this reason, conventionally, when an ellipse occurs in a tube, it is manually corrected by using a simple press device or the like.

[0003]

However, particularly when casting a thin-walled tube, an ellipse is likely to occur, and if all of this is corrected manually by hand as in the conventional case, the workability is extremely poor. There is a point. Also, especially for thin-walled tubes,
There is a problem that it is more difficult to correct than a normal thick tube. In addition, for the convenience of joining the pipes, it is usually necessary to correct only the ellipse of the insertion port, but in the case of a cast pipe that may be cut at the laying site, the ellipse should be made over the entire length of the pipe beforehand. There is also a problem that it must be corrected with high accuracy.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve such a problem and to make it possible to correct an ellipse generated in a thin-walled casting pipe particularly efficiently and over the entire length of the pipe.

[0005]

To achieve the above object, the apparatus of the present invention has a receiving port at one end and horizontally supports a casting pipe immediately after being subjected to an annealing treatment after casting, and
A pair of support drive rolls for rotating the casting pipe around its axis, and a straightening roll for radially pressing the rotating casting pipe supported on the support drive rolls, and the support drive rolls. The straightening roll is configured to come into contact with the entire length of the tube excluding the receiving port.

In the method of the present invention, the apparatus having the above-mentioned configuration is used to perform a straightening operation by applying an excessive pushing amount to the straightening roll by a first set amount with respect to a predetermined outer diameter of the pipe at room temperature,
After that, a straightening operation is performed by giving an excessive pushing amount to the straightening roll by a second set amount smaller than the first set amount with respect to a predetermined outer diameter of the pipe at room temperature.

[0007]

According to the apparatus of the present invention, the tube immediately after being subjected to the annealing treatment is subjected to the correction of the ellipse over the entire length by the hot rolling utilizing the residual heat of annealing.

Further, according to the method of the present invention, the pipe is straightened by the pushing amount of the straightening roll which is excessive by the first set amount with respect to the predetermined outer diameter of the pipe at the normal temperature, and then the first set amount is used. Since the straightening work is performed by giving an excessive amount of indentation to the straightening roll by a small second set amount, the elasto-plastic straightening by the two-stage press becomes possible. Therefore, even if the cast pipe is thin, the straightening can be performed efficiently.

[0009]

1 and 2, reference numeral 1 denotes an annealing furnace, which supports a cast iron pipe 2 after centrifugal casting in a horizontal direction and conveys the pipe 2 in a direction perpendicular to an axis thereof. Is annealed at a predetermined temperature. An outlet 3 of the annealing furnace 1 is provided with a liftable opening / closing lid 4.

In the immediate vicinity of the outlet 3 of the annealing furnace 1, a straightening device 5 according to the present invention is installed. In this straightening device 5, reference numeral 6 is a frame, and a pair of horizontal support drive rolls 7, 7 are provided at the lower portion of the frame 6.

The pair of support drive rolls 7, 7 are horizontally spaced from each other, both ends of which are supported by bearings 8, 8 and the center of which is supported by a support roller 9. ing. Further, by being connected to the motor 10, it is configured to rotate around the axis. By placing the cast iron pipe 2 between the rolls 7 and 7, the cast iron pipe 2 is supported in the horizontal direction over its entire length while being rotated by the rolls 7 and 7 about the axis. become. At the ends of the support drive rolls 7, 7, there is a small diameter portion 12 for avoiding contact with the receiving port 11 of the tube 2.
Are formed.

A straightening roll 13 is provided on the upper portion of the frame 6, and both ends of the straightening roll 13 are supported by bearings 14, 14 that can move up and down along the frame 6. Both bearings 14 and 14 are attached to the frame 6 and are respectively connected to the straightening cylinders 15 and 15 that expand and contract in the vertical direction. By operating the straightening cylinders 15 and 15, the bearings 14 and 14 are supported by the support drive rolls 7 and 7. The straightening roll 13 can be pressed against the upper surface of the formed tube 2. At the end of the straightening roll 13 is also formed a small diameter portion 16 for avoiding contact with the receiving port 11 of the tube 2. The elevation control of the straightening roll 13 is performed using a digital hydraulic servo mechanism.

The outlet 3 of the annealing furnace 1 and the supporting drive rolls 7, 7
A pipe diameter discriminating device 17 is provided between and. Here, 18 is a support roller, which supports the tube 2 to define the lower surface position of this tube. 19 is a stopper, which distinguishes the tube 2
Hold on 17 An elevating type contact plate 20 is provided above the support roller 18, and from the position of the contact plate 20 when the contact plate 20 hits the straight pipe portion near the receiving port 11 of the pipe 2, The diameter of 2, that is, the pipe type is determined. 21 is a back plate
An actuator for raising and lowering 20 is supported by a bracket 22 attached to the frame 6.

Next, the correction work will be described. The tube 2 cast by the centrifugal casting method or the like is passed through the annealing furnace 1 after the casting, undergoes heat treatment, and is carried out from the outlet of the annealing furnace 1.
Then, the abutting plate 20 is abutted on the roller 18 of the discriminating device 17 while being supported in the horizontal direction, so that the diameter, that is, the pipe type is discriminated.

The pipe 2 of which the pipe type has been determined is then sent to the straightening device 5 and supported in the horizontal direction by the supporting drive rolls 7 while holding the residual annealing heat. Also the motor 10
Is driven to rotate about the axis by the support drive rolls 7, 7. In this state, the straightening cylinder 15 is moved down by the straightening cylinder 15 and pressed against the upper surface of the tube 2 to correct the ellipse. The correction conditions are as follows, for example.

First, as a first step, an excessive pushing amount of 8 to 15 mm is applied to the straightening roll 13 with respect to the regular outer diameter of the pipe at room temperature. That is, the outer surface of the straightening roll 13 is inserted inward in the tube radial direction by 8 to 15 mm from the outer surface of the tube 2, and the tube 2 is rotated around the axis while forcibly deforming the tube 2. If, for example, the pipe 2 makes 5 revolutions in this state, the excessive pushing amount of the straightening roll 13 is set to 2 as the second step.
Reduce to ~ 5mm. Then, in this state, the tube 2 is rotated three times, for example.

At this time, the tube 2 retains the annealing residual heat as described above, and the ellipse is corrected by hot rolling at 700 to 500 ° C. By performing the two-step pressing as described above, the pipe 2 can be elasto-plastically corrected, and even the thin cast iron pipe 2 can be efficiently corrected.

That is, as shown in the drawing, three rolls 7,
When the pipe 2 is rotationally straightened by the pipe 13, a large compressive strain is generated in the pipe 2 in the portion of the straightening roll 13. Further, in the portion of the tube 2 between the straightening roll 13 and the support drive roll 7, a tensile strain smaller than the compressive strain is generated. When the tube 2 to be corrected rotates, this strain is continuously and repeatedly applied to the entire circumference of the tube 2 to cause a certain plastic deformation of the skin of the tube 2, thereby bringing the tube 2 close to a perfect circle. ..

At this time, in the case of a thick-walled tube, the amount of strain required for correction, that is, the skin yield stress that causes a constant plastic deformation can be obtained with only a small reduction amount. However, in the case of the thin-walled tube as described above, the skin yield stress necessary for straightening cannot be obtained unless a large amount of reduction is applied as compared with the thick-walled tube. On the other hand, if a large amount of reduction is applied to the thin-walled pipe, a problem of local residual strain during unloading occurs.

In general, in order to prevent local residual strain, it is sufficient to slow down the unloading speed so that the strain on the surface of the pipe is evenly distributed over the entire circumference. The phenomenon of becoming larger than the standard is caused, and in addition, the temporal processing capability becomes very poor.

Therefore, by adopting the above-described two-step pressing method, it is possible to solve the problem at the time of correcting such a thin-walled tube. According to this, the unloading is performed in two steps, and the correction time is suppressed to the minimum, and the increase of the outer shape of the pipe, the occurrence of local residual stress, the deterioration of time efficiency, etc. are all taken care of. It can be prevented. This is effective by stopping the unloading once in the unloading process and rotating the tube several times under a small amount of reduction as described above.

Further, by performing the digital hydraulic servo control on the position of the straightening roll 13 as described above, the pushing amount of the straightening roll 13 can be precisely set, and high-speed and high-precision straightening work can be performed. FIG. 3 shows a comparison between the amount of ellipse before correction and the amount of ellipse after correction according to the present invention for tubes of each diameter. As shown in the figure, the ellipse is effectively corrected in any of the tube types.

Further, by adopting the digital hydraulic servo mechanism, it is possible to precisely set the straightening press conditions for all the pipe types even if the casting pipe 2 has various pipe types. Moreover, since all the pipes 2 carried out from the annealing furnace 1 are straightened, the quality of the pipes 2 can be leveled with high quality. For example, as shown in FIG. 3, it is possible to correct as many as 60 tubes 2 in one hour by setting the elliptic amount of a 6 m long tube having a diameter of 300 mm to 800 mm to 3 mm or less.

Since the straightening is carried out over the entire length of the tube 2, even if the tube 2 is cut at any position thereafter, an elliptical straightened cut can always be obtained. Further, since it is directly connected to the annealing furnace 1 that performs continuous processing and straightening is performed including discrimination of the pipe type, automatic unattended operation of the entire equipment is possible. The straightened tube 2 is carried out of the straightening device 5 as shown in FIG.

[0025]

As described above, according to the apparatus of the present invention, the cast iron pipe immediately after being subjected to the annealing treatment is provided with the supporting drive roll and the straightening roll over the entire length by the hot rolling utilizing the residual annealing heat. The ellipse can be corrected efficiently. Therefore, even if the cast iron pipe is cut at any position thereafter, it is possible to always obtain an elliptic straightened cut end.

According to the method of the present invention, the pipe is straightened by the pushing amount of the straightening roll which is excessive by the first set amount with respect to the predetermined outer diameter of the pipe at the room temperature, and thereafter, the straightening amount is smaller than the first set amount. Since the straightening work is performed by giving an excessive amount of pushing to the straightening roll by the second set amount, elasto-plastic straightening is possible with a two-stage press, and even with thin-walled pipes, this can be performed at high speed and with high accuracy. Can be elliptical corrected.

[Brief description of drawings]

FIG. 1 is a front view of a tube elliptical straightening device according to an embodiment of the present invention.

2 is a side view of the elliptical straightening device for the tube of FIG. 1. FIG.

FIG. 3 is a diagram showing an example of measurement results of an ellipse before and after correction.

[Explanation of symbols]

 1 Annealing furnace 2 Cast iron pipe 5 Straightening device 7 Support drive roll 13 Straightening roll 17 Discriminating device

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Koji Nakakubo 2-26 Ohama-cho, Amagasaki-shi, Hyogo Stock company Kubota Mukogawa Works (72) Inventor Motoki Onishi 2-26 Ohama-cho, Amagasaki-shi, Hyogo Stock company Kubota Mukogawa Works

Claims (2)

[Claims] 1. A pair of support drive rolls which have a receiving end at one end and horizontally support a cast pipe immediately after being subjected to annealing treatment after casting and rotate the cast pipe around its axis. And a straightening roll that presses the casting pipe that is supported on these supporting drive rolls and that is rotated in the radial direction, and the supporting drive roll and the straightening roll are in contact with the entire length of the pipe excluding the receiving port. An elliptical straightening device for a tube, characterized in that it is configured. 2. A method for straightening an ellipse for a pipe using the straightening device according to claim 1, wherein the straightening roll is provided with an excessive pushing amount by a first set amount with respect to a predetermined outer diameter of the pipe at room temperature. And then perform a straightening operation by applying an excessive pushing amount to the straightening roll by a second set amount smaller than the first set amount with respect to the predetermined outer diameter of the pipe at room temperature. It is characterized by performing.