JPS6235844B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing seamless pipes.

The production of non-welded metal as seamless pipes mainly involves two continuous processes: the process of drilling holes in the axial direction in the raw rod that comes out of the heating furnace to create _a thick hollow blank, and the process of creating a thick hollow blank. The rolls of the mill are arranged at an angle of ₉₀ degrees, and the mill rolls the hollow blanks in a mill.
The hollow blank such that the total thickness reduction made until e ₀ reaches the end of the mill corresponds to the desired tube thickness.
Decrease the thickness of e ₀ .

The drilling process is generally carried out by pressing a rotating blank rod e against a drilling head carried by a mandrel M held in a predetermined position. The thick hollow blank e ₀ is thus forced through the mandrel M carrying the drilling head. On the other hand, there are two conventional rolling methods: a flexible mandrel rolling method and a fixed mandrel rolling method.

In the case of swivel mandrel rolling, a long mandrel is introduced into the hollow blank and a thrust member forces the hollow blank onto the mandrel into engagement within the mill. The metal tube being rolled between the rolls and the mandrel is therefore elongated. The mandrel is free and takes an average speed which will be determined from the speed of the metal tube at each roll position in the mill.

The assembly of the mandrel and the rolled blank partially covering the mandrel is placed on the exit side of the mill on a mandrel release device, where the mandrel is released. The rolled hollow blank is transferred to processing areas such as heating and calibrating, while the long mandrel is selected for the mandrel cooling system and lubricating mechanism for initial stretching. He is sent back to the bench.

Although for common applications, this flexible mandrel rolling process has several drawbacks.
The length of rolled blanks with limited thickness is 100 mm in diameter
It will be limited to approximately 25 meters in millimeters and approximately 30 meters in diameter of approximately 140 millimeters. This limitation is necessary because the finished blank may slump during the mandrel dissociation. Furthermore, the length through which the mandrel penetrates into the rolling blank, and therefore the mandrel release length, is very important, being 21 m for a 25 m rolling blank and 26 m for a 30 m rolling blank.
This means meters. This is a considerable length and promotes the collapse of thin-walled rolled blanks.

Fixed mandrel rolling also involves introducing a mandrel into a hollow blank on the inlet side of the mill. The hollow blank and mandrel combination is pushed inside the mill, but the mandrel is fixed and the distance from the position of the third to last roll is generally smaller than the distance from the position of the third to last roll. It only travels short distances.

Once rolling is complete, the rolled blank E is ejected from the last roll position of the mill to release the mandrel. The mandrel is then returned from the final cage to the beginning of the mill to wait for the next hollow blank e ₀ to be in place.

This fixed mandrel rolling method also has some disadvantages. Although the working part of the mandrel is short, the speed of the metal tube is high compared to the speed of the mandrel. Therefore, the mandrel can become overheated and suffer excessive wear. Furthermore, this method requires that the mandrel be completely retracted before being introduced into the next hollow blank.
Furthermore, since the same mandrel is usually used for successive hollow blanks, the result is that the mandrel is not adequately cooled between two successive rollings.

The present invention overcomes the deficiencies of the prior art described above with respect to the separation process of the product and mandrel, which limits the product length and product properties, especially in the manufacture of metal tubes without a welding process as seamless tubes. Concerning new and improved methods.

In the present invention, a mandrel M having an outer diameter d _M is provided where the bare rod e supports a drilling head (drilling tool) having an outer diameter d _H.
and then this mandrel M and the inner diameter d ₀
The combination with the hollow blank e ₀ enters a continuous mill 12 and the mandrel M is rolled during the rolling process at a speed calculated such that its effective length is at least equal to the length absolutely necessary for the rolling process. It is maintained. In other words, a combination of a hollow blank e ₀ and a mandrel M of a predetermined length inserted into the hollow blank e ₀ is introduced into the mill 12 and is stretched while being stretched during the rolling process. When the tip of the hollow blank e ₀ moving in the axial direction passes the last roll positioning part (also referred to as a stand) in the mill 12, the tip of the mandrel M at least reaches the position of the last roll. When the rolling of the hollow blank _e0 is completed, the mandrel M is sent out of the mill 12 together with the rolled blank E. A mandrel disassembly device 15 removes the mandrel M from the rolled blank E, and the rolled blank E is sent further to a normal processing area, while the mandrel M is cooled, inspected and lubricated. and returned to the tip of the device for drilling the next blank rod.

Thus, the mandrel M supporting the perforation head of the present invention functions as a perforation rod for perforating the raw rod e in the axial direction in the first manufacturing process area, and then as a rolling mandrel in the second rolling process area. The function of In order for this mandrel M to act as a drilling rod, it must be fitted with a drilling head at the beginning of the process cycle. Thus, the drilling head may remain attached to the mandrel M during the entire cycle, or it may be released from the mandrel M by the head disassembly device 23 at a certain stage during the process cycle and its own cooling check cycle may be performed. may be constructed and mounted on the mandrel M again, or may be mounted on another mandrel M in a certain process area of the cycle of the mandrel M.

The device for achieving the method according to the invention comprises a mandrel M which moves forward or backward in the direction of the positioning of the rolls in the perforation device 4 for perforation of the blank rod e and is equipped with a perforation head.
and a mandrel guide device for supporting the mandrel M and preventing the mandrel M from falling, which is disposed between the roll positioning and the support stop member 7. 8, an injection device ₉ for injecting the combination of mandrel M and hollow blank e ₀ when mandrel M is released from its support stop device 7; a duct 10 for axially positioning against the rolling
A mechanism 13 for capturing the rear end of the mandrel M, an inlet duct 11, a mill 12 having a plurality of rolls appropriately positioned with angular shifts, and a hollow blank E are injected toward the mandrel disassembly device 15. Exit duct 13A for mills with a mechanism to
, a mandrel disassembly device 15 equipped with a rolled semi-finished product removal mechanism and a mandrel removal mechanism, a device for collecting the mandrels M and returning them to the first step, and a rolling semi-finished product E further removed by a conventional method. equipment that transports the equipment to the equipment in the processing area.

The equipment that collects the mandrels and returns them to the equipment in the first process area includes a mandrel cooling tank 17 and a mandrel inspection platform 20.
, an oil application device 21 , a duct 22 for aligning the mandrel M in front of the punching device 4 , and a device for feeding the mandrel M to the punching device 4 . It should be noted that the present invention can also be applied when the drilling of the bare rod e is carried out separately.

There are many advantages arising from the present invention. These are related to continuous rolling technology and perforation technology, and are related to productivity or investment aspects.
Furthermore, it is related to the operating costs of the equipment. That is, by using the mandrel M as a punching rod and also as a rolling mandrel at the same time, it is possible to reduce the clearance between the mandrel M and the inner diameter of the hollow blank e ₀ and to reduce the clearance between the mandrel M and the inner diameter of the hollow blank e ₀ . A certain reduction in the outer diameter, that is, a certain reduction in the wall thickness is possible, and a part of the hollow blank e ₀ is crushed between the rollers of the pair of first rolls in the mill 12 and protrudes from the side. This makes it possible to reduce the number of burr-like protruding edges and to simplify the engagement of the hollow blank e ₀ in the positioning of the first roll of the mill 12.
Furthermore, since the mandrel is of constant rather than varying speed during rolling, the conditions for deformation of the metal tube in the channel, i.e. the passage for the hollow blank e ₀ to pass between the positions of the rolls, are limited to the mandrel. does not change due to changes in the speed of
"Deformation" of the metal tube due to this phenomenon of velocity change
will not be seen in any case, rolling can be done with the rolls having the channel positioned to make the wall thickness of the metal tube uniform, and mandrel dissociation can also cause deformation. It is easier to do without.

Since the limit of penetration of the mandrel M into the hollow blank e ₀ is much lower than in the flexible mandrel rolling method, the mandrel dissociation time is shorter and the mandrel can be dissociated under optimal conditions. .

Therefore, the present invention has the following advantages: the length of the mandrel can be shortened, the mandrel M carrying the drilling head is employed, so a drill rod is not required, and the number of mechanisms required to circulate the mandrel M is reduced. The fact that the mandrel dissociation bench 15 requires less power is an advantage in terms of investment and operating costs.

In FIG. 1, reference numeral 1 indicates a heating furnace such as a rotary hearth furnace. A raw rod e is extruded from the heating furnace 1, passes through an alignment device 2, and is inserted into a punching device 4 such as an oblique mill. e is conveyed to a known feeding device 3 for feeding e.

The rolls of the perforating device 4 are driven by a motor 5 via an elongated shaft 6. A support stop member 7 is arranged in connection with the perforation device 4, which support stop member 7 can be advanced or retracted in the direction of roll positioning in the perforation device 4 and accommodates a mandrel M with a perforation head. It is designed to. Between the perforation device 4 and the support stop 7, indicated schematically by the reference numeral 8 is a conventional mandrel guiding device, i.e. a guiding device for tubular blanks _e0 , which guiding device 8 is To align the mandrel M and prevent the mandrel M from falling. The combination of mandrel M and hollow blank e ₀ is injected through an injection device 9, which is known per se, after the mandrel M has left its support stop 7. The longitudinal positioning of the hollow blank e ₀ relative to the mandrel M is adjusted in a positioning duct 10 with a feeder and an ejector.

The inlet duct 11 of the mill 12, in which a plurality of rolls are positioned and arranged angularly offset by 90 DEG, is arranged adjacent to and parallel to the positioning duct 10.
A capture mechanism 13 located at the rear end of the inlet duct 11 is designed to capture the rear end of the mandrel M and release the mandrel M upon completion of the rolling operation, the capture mechanism 13 being mechanically or hydraulically ,
or during the rolling of the hollow blank e ₀ using an electrical device to adjust to a predetermined speed.

The outlet duct 13A of the mill 12 has an injection device 14 which delivers the partially engaged combination of mandrel M and rolled blank E to a mandrel disassembly device 15. The device, consisting for example of a mandrel disassembly device 15 with a moving mechanism, moves the rolled blank E to the platform 16 and also the mandrel M to the cooling tank 17.

The tip of the rolled semi-finished product E is cut by the cutting member 18, and after that, the rolled semi-finished product E is sent to a conventional heating furnace 19, where it is just finished. be made into The mandrel M cooled in the cooling tank 17 is then
It is moved onto the inspection platform 20 and is then lubricated in a lubricating device 21 before reaching the duct 22 where it is realigned with the drilling device 4 . In this way, the mandrel M is connected to the punching device 4, the mill 12, and the mandrel separating device 15.
It will be clear that a single period passing through .

In the illustrated embodiment, considered the most advantageous, the tip of the mandrel M carrying the drilling head is located at the mill 12.
It is opposite the tip of the mandrel that will be introduced.
However, it would also be possible to employ a reverse arrangement, ie a reversible arrangement in which the tip of the mandrel M carrying the drilling head becomes the tip of the mandrel M which is directly introduced into the mill 12. Reference numeral 23 designates a head release device for separating the drilling head from the mandrel M. However, the drilling head may remain attached to the mandrel M during one cycle, or it may be detached from the mandrel M at any other suitable stage of the cycle that the mandrel M constitutes.

FIG. 2 shows three graphs showing the movement of the blank as a function of time in solid lines and the movement of the mandrel as a function of time in dashed lines;
Graph B relates to the conventional flexible mandrel rolling method, graph B relates to the conventional fixed mandrel rolling method, and graph C relates to the novel rolling method according to the present invention.

In the case of method A, after rolling, the rolled blank product
A mandrel M ₁ of considerable length is used which engages almost the entire length of E ₁ . In method B, the mandrel M ₂ is fixed and only moves during rolling a distance approximately corresponding to the distance from the third to last position (indicated by the reference sign) to the last position ( ) of the mill. do not have. When the rolled blank E ₂ leaves its last position ( ), the mandrel M ₂ makes a return movement so that it can engage another hollow blank. In the case of the method according to the invention shown in diagram C, it is sufficient to use a mandrel M that is significantly shorter than the mandrel M ₁ used in the universal mandrel rolling process. The mandrel M is kept at a constant speed while the hollow blank e ₀ passes through the mill 12, after which the combination of the mandrel M and the rolled blank E is transferred to the mandrel disassembly device 15. dissociated. It is clear that the mandrel M only engages a certain length into the rolling blank E, which proves some of the advantages previously mentioned.

The length of the mandrel M pulled out from the rolled blank E does not constitute a constraint as in the flexible mandrel rolling method, so the length of the blank must be limited to 25 m or 30 m. There is no need to make the limitations that were necessary in the prior art.

For example, in a mill that manufactures rolled blanks with a diameter of 100 mm from a 3.8 m raw bar, a length of 16.5 m is
It is possible to produce rolled blanks with a length of 44 m on a mandrel. The blank was transformed into a tube with a diameter of 21.3 mm, a length of 2.3 mm, and a length of 300 m using a drawing-type reducing socket. The basic calculation formula regarding the length and speed of the mandrel M in the present invention will be explained below with reference to FIG.

(1) Regarding calculation of the minimum length L _M minimum of the mandrel M. Also, minimum = minimum is abbreviated as mini.

In addition, each symbol shall be defined as follows.

V _D ... Speed of mandrel M _M ... Length of mandrel M L ₀ ... Length of hollow blank e ₀ before rolling L _L ... Length of mill 12 L _I ... Length of blank E after rolling T _R ... Time from when the tip of the hollow blank product e ₀ enters the mill 12 to when the tip crosses the mill 12 T _S ... Time from when the tip of the hollow blank product e ₀ crosses the mill 12 Time from the time of cutting until the rear end of the hollow blank e ₀ crosses the mill 12 T _T ...Total rolling time T _T = T _R + T _S l... Between the positioning part of the roll and the positioning part of the roll distance or the distance between the positioning parts of two rolls l ₁ ... Length of the mandrel M protruding from the tip of the hollow blank e ₀ before rolling l ₄ ... After the hollow blank e ₀ before rolling Length of the mandrel M protruding from the end l ₃ ... Length of the mandrel M inside the rolled blank E after rolling V _E ... Speed of the hollow blank e ₀ at the entrance of the mill 12 V _S ... Velocity of the hollow blank e ₀ at the exit of the mill 12 T _V ... Empty time α... Degree of elongation of the hollow blank e ₀ A... Total elongation of the hollow blank e ₀ in the mill The minimum length L _Mnioi of the length L _M of the mandrel M is calculated on the premise that the rear end of the mandrel M coincides with the rear end of the hollow blank e ₀ .

In Figure 3, ==+=L _L +V _D・T _S However, in the triangle ACG, V _D =AC/CG=AB+BC/CG=l ₄ +L ₀ /
T _T Therefore = L _L + (l ₄ + L ₀ ) T _S / T _T Now if l ₄ = O, _nioi = L _L + L ₀ T _S / T _T ∴L _Mnioi = L _L + L ₀ T _S / T _T …(1) becomes.

The velocity of the hollow blank e ₀ at the entrance of the mill 12 is V _E .

If L _I is the degree of elongation of the hollow blank e ₀ at the positioning part of the roll, then the velocity V _I of the hollow blank e ₀ at the exit of the positioning part or the entrance of the positioning part is V _I = V _E・α _I …(2).

If l is the distance between the positioning parts of the roll, the time △T to cross this distance l is △T ₍

Claims (1)

[Claims] 1 The raw rod e is attached to the drilling head carried by the mandrel M.
In order to form a hollow blank e ₀ through which the mandrel M is inserted, the blank rod e is stretched over a drilling head supported by the mandrel M, and the mandrel M having the drilling head and the hollow Semi-processed products
Transfer the combined body with e ₀ to the entrance of the continuous mill 12,
Next, the combination of the mandrel M and the hollow blank _e0 is inserted into the continuous mill 12, and when the hollow blank _e0 is inserted into the inlet stand of the continuous mill 12, the tip of the mandrel M is connected to the continuous mill. When the tip of the hollow blank e0, which is located in the continuous mill 12 and is stretched and moves in the axial direction before the exit stand of the continuous mill ₁₂ , passes through the final stand () part of the continuous mill 12. , a method for manufacturing a seamless pipe, characterized in that the mandrel M is given a speed calculated such that at least the tip of the mandrel M is within the final stand ( ) portion.