JPH0415045B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tube cutting method for cutting continuously fed tubes into predetermined lengths in an electric resistance welded tube manufacturing facility.

[Prior Art] Cutting devices used in electric resistance welded pipe manufacturing equipment must perform running cutting, in which cutting is performed while moving along with the continuously fed pipe, and for this reason, the premise is that the cutting can be done in a short period of time. becomes. Conventional cutting methods that meet this assumption include friction cutting by rotating a saw blade (friction saw) at high speed, a method in which a blade built into a die set is swung down and sheared to cut off the thickness of the blade, and a method in which sharp outer edges are A method using a rotary disk cutter (only for round pipes), in which a plurality of circular blades are rotated in the circumferential direction around the pipe and narrowed down to cut the pipe, and a cutting method using a plasma arc, etc. have been adopted.

[Problems to be Solved by the Invention] Each of the conventional cutting methods described above has a problem in that the vicinity of the cutting opening is deformed or burrs are generated at the cutting opening. For example, in the method using a die set, there is no lower cutter in the upper part of the pipe cross section and the pipe is simply pierced with a cutter, so deformation is large, especially in the case of square pipes. Burrs may also occur. In the case of rotary disk cutters, the burrs are large. In the case of friction saw or plasma arc cutting, deformation is not so much of a problem, but the occurrence of burrs is significant.

The above-mentioned deformations are corrected or re-cut in the post-process, and burrs and burrs are removed using a grinder, etc. in the post-process, but this work is not easy.
It requires a lot of effort.

Furthermore, as mentioned above, it is extremely important that the time required for cutting is short, and this often limits the tube manufacturing speed, but with methods other than the die-setting method, it is desirable to be able to cut in an even shorter time.

This invention aims to solve the above-mentioned conventional problems, and is a pipe cutting method for use in electric resistance welded pipe manufacturing equipment that does not cause deformation, burrs, or burrs at the cutting end, and allows cutting in a short time. The purpose is to obtain.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, at the stage of the round raw pipe after electric resistance welding and before passing through the sizing roll, the raw pipe at the position to be cut is After making a cut all the way around the outer circumference and applying reduction with a sizing roll to make a perfect round or square tube of a predetermined shape and size, the tube is gripped at the front and back of the cut position with chucks, and then Only the chuck on the downstream side was driven to rotate reciprocatingly in forward and reverse directions to break the cut portion.

[Function] When the chuck on the downstream side is reciprocally rotated in the forward and reverse directions, twisting force is applied to the pipe, stress is concentrated at the notch due to the notch effect, and the pipe breaks at the notch. In this case, since the tube is twisted back and forth in the forward and reverse directions, severe stress is generated at the cut portion, so that cutting is possible even if the distance between the front and rear chucks is somewhat wide.

[Example] An example of the present invention will be described below with reference to FIGS. 1 to 8.

FIG. 1 is an overall side view of an electric resistance welded steel pipe manufacturing facility to which the cutting method of the present invention is applied. A coiled hot rolled steel strip 2 supported by an uncoiler 1 is fed out by pinch rolls 3, flattened by a leveler 4,
A shear 5 and an end welder 6 make a welded connection between the rear end of the previous coil and the tip of the next coil, and an underground louver is used to maintain the supply of material to the pipe making machine during this welded connection. 7 and then sent to breakdown roll 8 of the pipe making machine. In this breakdown roll 8, the steel strip is formed into a semicircular shape, and then in the subsequent fin pass roll 9, it is formed into a substantially circular shape, and the edges are electrically welded by a high frequency resistance (or induction) welding machine 10, and this welded part is The excess thickness is removed by a bead trimmer 11, thus forming a round blank tube. Further, 12 is a cooling table for pouring cooling oil to cool the welded part, 13 is a sizing roll for applying reduction to the round blank tube and forming it into a perfect round tube or a square tube with predetermined dimensions; 14 is a cooling table for cooling the welded part; A Turkshead roll corrects warpage, bending, and twisting of the pipe, and a runout table 15 sends out the cut product, and the above structure is the same as the conventional one.

Conventionally, a cutting machine is only installed downstream of the Turks head roll 14 (right side in the figure), but in the present invention, a cutting machine is installed upstream of the sizing roll 13 on the outer periphery of the round blank tube at the position to be cut. A traveling type cutting machine 16 is installed to form a cut over the entire circumference, and on the downstream side of the Turks head roll 14, the pipe is gripped by a chuck before and after the cut part, and only the chuck on the downstream side can be turned in the forward or reverse direction. A twist cutting machine 17 is installed which rotates the pipe reciprocally in the direction of the pipe to twist the pipe and break the cut portion. Note that the forward and reverse rotational drive is not limited to one reciprocation, but may be one and a half reciprocations, two reciprocations, or the like.

In addition, in the embodiment, in order to make it easier to keep the depth of the cut by the cutting machine 16 constant over the entire circumference, on the upstream side of the cooling table 12,
A presizing roll 18 is installed to make the as-welded round pipe into a roughly perfect circle. Note that this presizing roll 18 is different from the sizing roll 13, which is used to obtain a predetermined shape and dimensions, and is simply used to obtain a roughly perfect circle without regard to dimensions. Therefore, the tube immediately after leaving the presizing roll 18 is also referred to as a round blank tube. It does not necessarily need to be installed as long as a constant depth of cut can be obtained.

FIG. 2 shows a rotary disk cutter which is an example of the cutting machine 16 mentioned above. This rotary disk cutter 19 is equipped with, for example, three circular blades 20 having acute-angled outer peripheral edges, and is driven by a drive device 21 to rotate each circular blade 20 in the circumferential direction around the round blank tube A while narrowing it down. , make a cut to a predetermined depth on the outer periphery of the raw pipe A. The rotary disk cutter 19 grips the raw pipe A with a clamp (not shown), and forms the above-mentioned cuts while traveling together with the raw pipe A. Other cutting machines include rotary bit cutters with rotating bits,
Various machines used for cutting round tubes can be used.

An example of the depth and shape of the cut formed by this cutting machine 16 is shown in FIG. 3, and FIG. 4, which is an enlarged view of part A in FIG. Depth of cut B h
is set to an optimum depth so that the material does not break during the sizing process in which it passes through the sizing roll 13, and the cut surface does not deform during cutting. The depth h varies slightly depending on the pipe shape, material, plate thickness, etc., but for example, according to experiments with a 3.2 mm x 60 mm x 60 mm square steel pipe, it is usually about 60% to 75% of the plate thickness t. , without any breakage during the cornering process.
Good cutting was achieved with almost no deformation, burrs, etc. The shape of the cut B is preferably a V-shape, or a two-step V-shape with a large inclination angle at the tip to reduce wear on the blade, as shown in FIG. In the illustrated example, one side of the tip is sloped at 75° and the other side is sloped at 15°.

Figures 5 and 6 show an embodiment of a chuck for gripping a rectangular tube. 22 is a chuck on the stationary side, 23 is a chuck on the downstream side, that is, the rotating side, and both chucks 22 and 23 consist of a pair of upper and lower parts each having a U-shaped recess 23a that matches the side dimension of the square tube.
For example, as shown in FIG. 7 (this is the rotating side), the chuck guide 25 is moved up and down by the hydraulic cylinder 24 to grip or release the rectangular tube. Although the chuck guide on the fixed side does not rotate, the chuck guide 25 on the downstream side shown in FIG.
is fixed to a rotatably provided housing 26, and this housing 26 is driven to reciprocate and rotate in the forward and reverse directions of the arrow by a mechanism of a worm 27 and a worm wheel 28, so that only the chuck 23 on the downstream side is connected to the sixth chuck 23. It is designed to be driven to reciprocate and rotate in forward and reverse directions as shown by the arrows in the figure. In addition,
A mechanism using an air cylinder or another mechanism may be used to drive the rotation even more rapidly.

The chucks shown in FIGS. 5 and 6 are dedicated chucks for specific square dimensions, but as shown in FIG. 8, the chucks shown in FIGS.
According to the chucks 29, 29, which are arranged so as to be movable in the diagonal direction of the rectangular tube, various sizes can be accommodated.

To explain the timing of making a cut with the cutting machine 16 and cutting with the twist cutter 17, the cutting machine 16 is activated every time it is detected by a measuring roll or the like that the pipe has been fed a predetermined distance. For cutting, a notch detector is attached to the torsion cutting machine 17, and the operation of the chucks 22 and 23 is controlled by a signal from this notch detector that detects passage of the notch, so that the notch B is fixed. Check when the chucks 22 and 23 on the side and rotation sides are approximately at the center.

The cut detector may be a mechanical method of mechanically detecting the cut using a detector placed in contact with the pipe, a detection method using light reflection, eddy current flaw detection, ultrasonic flaw detection, or capacitance change detection. It is advisable to adopt the most suitable method, such as an electrical method of detection using techniques such as .

In the above-mentioned electric resistance welded steel pipe manufacturing equipment, welding machine 10
The welded round tube is removed by a bead trimmer 11 to remove excess thickness, and then passed to a presizing roll 18.
The cooling table 1 is made into an approximate perfect circle.
2, a cut B is made at a predetermined position by a cutting machine 16 over the entire circumference, and then a perfect round tube or a rectangular tube with a predetermined shape and dimensions is formed by a sizing roll 13. After being straightened, the chucks 22 and 23 of the torsion cutter 17 chuck the front and back of the notch B, and at the same time, the mechanism of the worm 27 and worm wheel 28 cuts the chuck 2 on the downstream side together with the housing 26 and the chuck guide 25.
3 is rapidly reciprocated in the forward and reverse directions, and accordingly, a twisting force is applied reciprocally by the chucks 22 and 23 on the front and rear of the tube, causing it to break at the notch B. After breaking, when the chucks 22 and 23 are opened, the product cut to a predetermined length is sent out through the run-out table 15.

In the above-mentioned cutting, the tube is twisted back and forth in the forward and reverse directions, so a severer stress is generated in the cut portion B, making it more likely to break than when the tube is rotated in only one direction. Therefore, compared to the case of one direction, it is possible to make the distance L between the front and rear chucks 22, 23 wider, and when gripping a pipe in actual equipment, both chucks 22, 23 can be used to secure the cut portion B.
The positional accuracy when gripping the front and back of the body no longer needs to be so precise. For this reason, both chucks 22,
It becomes easy to control the operation of 23, and it becomes easy to apply it in actual equipment. Further, regarding the rotation angle leading to cutting, the rotation angle from the normal position to one side can be smaller than that in the case of one direction, which is preferable in terms of equipment.

There are various conditions for obtaining a good cut, including the depth of the cut, the shape, the distance between the front and rear chucks, whether the notch is correctly centered between the front and rear chucks, and the speed of the chuck rotation drive. , and other factors, such as material, plate thickness, whether it is a round or square tube, etc.
It varies depending on its size etc. These settings may be set optimally through experimentation.

Although the present invention can be applied to both round tubes and square tubes, its advantages are more effectively utilized in the case of square tubes.
In other words, a rectangular shape generally makes it more difficult to cut than a round shape, but in the case of the present invention, the cut is formed in a round shape, so there are no disadvantageous conditions. Moreover, since the chuck is rectangular at the cutting stage, the shape of the chuck that grips the tube does not need to be exact, and a sufficiently large twisting force can be easily applied. Furthermore, during corner forming using the sizing rolls 13, the largest stress is applied to the corners of the square shape, making the corner parts more likely to break than the side parts, so the square pipe is twisted and broken. It is convenient for the above.

[Effects of the Invention] According to the method of the present invention explained above, a cut is formed in the pipe in front of the sizing roll, and after passing through the sizing roll, the front and back of the cut portion are grabbed by chucks, and only the chuck on the downstream side is turned in the forward and reverse directions. Since the pipe is cut by reciprocating rotation, various excellent effects are achieved as follows.

(i) Unlike the conventional methods, deformation of the cut portion,
The occurrence of burrs and burrs has been significantly reduced, and subsequent processes such as straightening, re-cutting, and removal are no longer necessary. Therefore, a great deal of labor is saved and processing equipment is no longer required.

(ii) The conventional rotary disc cutter applies twisting force to the pipe to cause it to break.
Compared to friction saws, plasma arc cutting methods, etc., cutting can be performed in a shorter time, and cases where the pipe production speed must be reduced due to limitations on cutting time have been largely eliminated.

(iii) Unlike the diamond-setting method, no chips are generated, so the material yield is improved, and there is no need to pause for scrap processing, improving work efficiency.

(iv) Unlike cutting with a friction saw, it does not generate problematically high levels of noise.

(v) Since it is driven to reciprocate in the forward and reverse directions, there is a wide limit to the distance between the front and rear chucks that allows for good cutting.
Therefore, it is easy to control the front and back of the cut portion to grasp it correctly, and it is easy to apply it to actual equipment.

[Brief explanation of drawings]

Fig. 1 is an overall side view of the ERW steel pipe manufacturing equipment to which the method of the present invention is applied, Fig. 2 is a front view of the main parts of the cutting machine, Fig. 3 is a side view of the pipe at the cutting part, and Fig. 4 is the 5 is a side view of the chuck portion, and FIG.
7 is a front view of the main parts of the twist cutting machine, and FIG. 8 is a sectional view showing another embodiment of the chuck. 13... Sizing roll, 16... Cutting machine, 1
7... Twisting cutting machine, 13... Presizing roll, 22, 23, 29... Chack, A... Round blank tube, B... Notch.

Claims (1)

[Claims] 1 After ERW welding and before passing through the sizing roll, a cut is made around the entire circumference of the round material pipe at the position where it should be cut, and reduction is applied by the sizing roll to form a true shape with a predetermined shape and dimension. After the tube is made into a circular tube or a square tube, the tube is gripped at the front and rear of the cut position by chucks, and then only the chuck on the downstream side is driven to reciprocate in forward and reverse directions to break the cut portion. A method for cutting pipes in ERW pipe manufacturing equipment.