CN110314951B - Method for manufacturing large-caliber high-strength thick-wall cold drawn pipe - Google Patents
Method for manufacturing large-caliber high-strength thick-wall cold drawn pipe Download PDFInfo
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- CN110314951B CN110314951B CN201910732626.4A CN201910732626A CN110314951B CN 110314951 B CN110314951 B CN 110314951B CN 201910732626 A CN201910732626 A CN 201910732626A CN 110314951 B CN110314951 B CN 110314951B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C1/00—Manufacture of metal sheets, metal wire, metal rods, metal tubes by drawing
- B21C1/16—Metal drawing by machines or apparatus in which the drawing action is effected by other means than drums, e.g. by a longitudinally-moved carriage pulling or pushing the work or stock for making metal sheets, bars, or tubes
- B21C1/22—Metal drawing by machines or apparatus in which the drawing action is effected by other means than drums, e.g. by a longitudinally-moved carriage pulling or pushing the work or stock for making metal sheets, bars, or tubes specially adapted for making tubular articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C3/00—Profiling tools for metal drawing; Combinations of dies and mandrels
- B21C3/02—Dies; Selection of material therefor; Cleaning thereof
- B21C3/06—Dies; Selection of material therefor; Cleaning thereof with adjustable section
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Abstract
The invention discloses a method for manufacturing a large-caliber high-strength thick-wall cold drawn pipe, and belongs to the technical field of cold drawn pipes. The method comprises the following steps: selecting a blank, carrying out surface treatment, carrying out first cold drawing, carrying out second cold drawing, straightening, carrying out heat treatment on a finished product, straightening and carrying out blanking measurement; the first cold drawing: the inner die and the outer die are installed on cold-drawing equipment, and an inner die sizing belt at the rear end of the inner die extends out of an outer die sizing belt at the rear end of the outer die by 5-30 mm; carrying out primary cold drawing on the blank; and the second cold drawing: adjusting the inner die to enable the inner die sizing belt to be aligned with the rear end of the outer die sizing belt; and carrying out secondary cold drawing on the blank. The invention needs cold drawing twice, but does not need to change the mould, and does not have the mould changing time in the traditional two-time cold drawing process; the second drawing in the scheme belongs to micro-deformation, generates a size effect under the action of micro-plastic deformation, plays a role in adjusting and improving the straightness, the roundness and the smoothness of the cold drawn pipe, and provides convenience for the subsequent straightening process.
Description
Technical Field
The invention relates to the technical field of cold drawn pipes, in particular to a method for manufacturing a large-caliber high-strength thick-wall cold drawn pipe.
Background
Cold drawn pipes in the industry are generally formed by multi-pass cold drawing and one-pass or two-pass continuous cold drawing;
for the steel pipe subjected to multi-pass cold drawing, if multiple heat treatments are not performed in the middle, the risk of generating fine cracks and even breakage exists, multiple groups of dies need to be replaced in the multi-pass cold drawing, the process is complicated, and the production efficiency is low;
although the development of large hydraulic cold drawing equipment is mature at present, the large hydraulic cold drawing equipment can provide enough drawing force and is convenient to produce. However, the wall thickness deviation of the large-caliber thick-wall cold-drawn pipe is large, and the straightness and the dimensional accuracy of the cold-drawn pipe cannot be guaranteed by one-time cold drawing. For the high-strength thick-wall pipe, the traditional drawing die has the risks of insufficient strength and insufficient constraint force, and if cold drawing passes are increased according to the traditional method, the cold drawing die needs to be replaced, so that the cold drawing cost is high, and the production efficiency is low;
therefore, on the premise of ensuring the quality of the high-strength thick-wall cold drawn pipe, cold drawing passes and die changing time are reduced, cold drawing cost is reduced, and yield is improved, so that the method is a development problem which is urgently needed to be solved in the cold drawing industry.
The Chinese patent discloses a steel pipe cold-drawing die (CN 102632093A) with twice diameter-changing and twice shaping functions, wherein a first conical surface diameter-changing belt, a first cylinder shaping belt, a second conical surface diameter-changing belt and a second cylinder shaping belt are sequentially manufactured on the outer circular surface of an inner die, and in one-pass cold drawing, the inner die has twice reaming diameter-changing and twice cylinder shaping, so that the workload of the original two passes is completed, and the production efficiency is improved by more than one time.
In the practical use process, the technology discovers that the continuous cold drawing of the steel pipe is realized by generating plastic deformation of the material twice through one-time cold drawing, but the technology has the following defects: :
(1) before cold drawing, annealing treatment of about 800 ℃ needs to be carried out on the hot rolled pipe blank, and the annealing treatment causes the increase of the cold drawing cost;
(2) before cold drawing, one end of the hot rolled pipe blank to be drawn needs to be turned to enable the hot rolled pipe blank to pass through a gap between the inner die and the outer die, and a turning section is in power connection with the cold drawing machine. The process of the headstock is added, so that the production process is complicated, the production period is long, and the cost is increased.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method for manufacturing a large-caliber high-strength thick-wall cold drawn pipe.
The invention is realized by the following technical scheme: a method for manufacturing a large-caliber high-strength thick-wall cold drawn pipe comprises the following steps:
selecting a blank, carrying out surface treatment, carrying out first cold drawing, carrying out second cold drawing, straightening, carrying out heat treatment on a finished product, straightening and carrying out blanking measurement;
the first cold drawing:
the inner die and the outer die are installed on cold-drawing equipment, and an inner die sizing belt at the rear end of the inner die extends out of an outer die sizing belt at the rear end of the outer die by 5-30 mm; carrying out primary cold drawing on the blank;
and the second cold drawing:
adjusting the inner die to enable the inner die sizing belt to be aligned with the rear end of the outer die sizing belt; and carrying out secondary cold drawing on the blank.
It further comprises the following steps: an inner die tapered reducing belt is arranged on the front side of the inner die sizing belt on the outer peripheral surface of the inner die; and an outer die tapered reducing belt is arranged on the front side of the outer die sizing belt on the inner peripheral surface of the outer die.
The inner die sizing belt and the outer die sizing belt are equal in length.
And during the first cold drawing and the second cold drawing, after the inner die, the outer die and the blank are arranged on the cold drawing equipment, the end part of the blank is extruded into the inner die and the outer die through the extruding head device.
Selecting XG900 and phi 416 × 24 from the blank, and cold-drawing to phi 416 × phi 378;
the first cold drawing:
the inner die and the outer die are installed on cold-drawing equipment, and an inner die sizing belt at the rear end of the inner die extends out of an outer die sizing belt at the rear end of the outer die by 30 mm; carrying out primary cold drawing on the blank, wherein the drawing force is 550T-650T;
and the second cold drawing:
reinstalling the inner die on cold-drawing equipment, wherein the inner die sizing belt is aligned with the rear end of the outer die sizing belt; and carrying out secondary cold drawing on the blank, wherein the drawing force is 150T-250T.
Compared with the prior art, the invention has the beneficial effects that:
1, although the scheme needs cold drawing twice, the mould does not need to be replaced, and the mould changing time in the traditional two-time cold drawing process is avoided; the second drawing in the scheme belongs to micro-deformation, generates a size effect under the action of micro-plastic deformation, plays a role in adjusting and improving the straightness, roundness and smoothness of the cold drawn pipe, and provides convenience for the subsequent straightening process;
2, because the second pass cold drawing only generates micro deformation, the size of the first pass cold drawing is stabilized, the residual stress generated by the first pass cold drawing is uniformly distributed, annealing is not required to be increased between the two pass cold drawing, the production cost is reduced, the straightness of the cold drawn pipe is better, and the precision of the finished pipe is favorably ensured;
3, an automatic head extruding and drawing device is adopted, so that the step of turning the head is omitted, and the production is convenient and rapid;
4, the problem that the mold is not strong enough and cannot play the same restraint function as the thin-wall pipe for the thick-wall pipe with high strength is solved. In the scheme, the first drawing force is about 600T, and the drawing force under the second micro-deformation is only about 200T, so that the drawing is easy; not only improves the safety of the cold drawing process, avoids the tube breaking caused by overlarge drawing force, but also improves the quality of the cold drawn tube.
Drawings
FIG. 1 is a schematic view of a first cold drawing pass;
FIG. 2 is a schematic drawing of a second cold drawing pass.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "opening," "upper," "lower," "thickness," "top," "middle," "length," "inner," "peripheral," and the like are used in an orientation or positional relationship that is merely for convenience in describing and simplifying the description, and do not indicate or imply that the referenced component or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be considered as limiting the present invention.
A manufacturing method of a large-caliber high-strength thick-wall cold drawn pipe is used for reducing the risk of one-pass drawing fracture of the large-caliber thick-wall pipe and solving the problem that the straightness and the dimensional accuracy of a finished pipe are difficult to guarantee by one-pass drawing when the wall thickness deviation of a large-caliber steel pipe is large. The method comprises the following steps:
selecting a blank, carrying out surface treatment, carrying out first cold drawing, carrying out second cold drawing, straightening, carrying out heat treatment on a finished product, straightening and carrying out blanking measurement;
the stock is selected from XG900 and phi 416 × 24, and is cold-drawn to phi 416 × phi 378, and the yield strength of the cold-drawn stock is as high as 900 MPa.
As shown in fig. 1, the main improvement points of the present embodiment are:
an inner die tapered reducing belt 1-2 is arranged at the front side of an inner die sizing belt 1-1 on the outer peripheral surface of the inner die 1; the front side of the outer die sizing belt 2-1 on the inner circumferential surface of the outer die 2 is provided with an outer die tapered reducing belt 2-2. Wherein, the inner die bearing belt 1-1 and the outer die bearing belt 2-1 are equal in length.
The first cold drawing specifically includes:
the inner die 1 and the outer die 2 are installed on cold drawing equipment, an inner die sizing belt 1-1 at the rear end of the inner die 1 extends out of an outer die sizing belt 2-1 at the rear end of the outer die 2 by 5-30 mm, and in the embodiment, the inner die sizing belt 1-1 is selected to be exposed by 30 mm. The aligned parts of the inner die sizing belt 1-1 and the outer die sizing belt 2-1 are shortened, and the blank is extruded by the outer die sizing belt 2-1 at first and then extruded by the inner die sizing belt 1-1, so that the wall is stably reduced, and the strength of the steel pipe is improved;
and (3) installing a blank, extruding the end part of the blank into an inner die 1 and an outer die 2 through an extruding head device, and finishing plastic deformation along the drawing direction through the restraint action of the inner die and the outer die under the drawing action of a hydraulic oil cylinder, wherein the drawing force is 550T-650T. When drawing for the first time, because the blank intensity is high, and belongs to thick-walled pipe, draw out the power great in the wall reduction process, the pipe tail straightness accuracy is relatively poor when taking off the pipe.
The second cold drawing specifically comprises:
removing the blank, and adjusting the inner die 1 to make the rear ends of the inner die sizing belt 1-1 and the outer die sizing belt 2-1 aligned;
and (3) installing the blank, extruding the end part of the blank into an inner die 1 and an outer die 2 through a head extruding device, and performing secondary cold drawing on the blank with drawing force of 150T-250T. The cold drawing for the second time is carried out under the constraint of the same group of inner and outer dies, and the inner die bearing diameter 1-1 is aligned with the outer die bearing diameter 2-1; during drawing, the blank is subjected to micro plastic deformation, and a size effect is generated under the action of the micro plastic deformation, so that the straightness, the size precision and the smoothness of the cold drawn pipe are improved.
The drawing force during the second cold drawing is only about 200T, the pipe can be stably taken off, the straightness of the tail of the cold drawn pipe during the first cold drawing can be effectively improved, and the roundness and the smoothness of the cold drawn pipe are improved, so that the specified size requirement is met. By adopting the cold-drawing process of the embodiment, the risks that the traditional die has insufficient restraining force on the high-strength thick-wall pipe and has insufficient dimensional accuracy can be reduced.
This embodiment can see that:
1, although the scheme needs cold drawing twice, the mould does not need to be replaced, and the mould changing time in the traditional two-time cold drawing process is avoided; the second drawing in the scheme belongs to micro-deformation, generates a size effect under the action of micro-plastic deformation, plays a role in adjusting and improving the straightness, roundness and smoothness of the cold drawn pipe, and provides convenience for the subsequent straightening process; the large-caliber high-strength thick-wall pipe can obtain good cold drawing quality, and the technical problem that the tail of the thick-wall steel pipe is bent and difficult to straighten in one-time cold drawing is solved;
2, annealing of hot rolled pipe blanks is not needed, annealing is not needed to be increased between two passes of cold drawing, the production cost is reduced, the straightness of the cold drawn pipes is better, and the precision of finished pipes is favorably ensured;
3, during the first cold drawing, the length of the alignment of the inner die sizing belt 1-1 and the outer die sizing belt 2-1 is shorter, and during the second cold drawing, the blank is slightly deformed, so that the step of turning the head can be omitted, an automatic head extruding and drawing device is directly adopted, and the production is convenient and fast;
and 4, the same inner die and the same outer die are adopted, and the drawing is performed twice after the positions are adjusted, so that the problems that the die is not enough in strength and cannot play the same constraint action with a thin-walled pipe on a thick-walled pipe with high strength are solved. In the scheme, the first drawing force is about 600T, and the drawing force under the second micro-deformation is only about 200T, so that the drawing is easy; not only improves the safety of the cold drawing process, avoids the tube breaking caused by overlarge drawing force, but also improves the quality of the cold drawn tube.
The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims (4)
1. A method for manufacturing a large-caliber high-strength thick-wall cold drawn pipe comprises the following steps:
selecting a blank, carrying out surface treatment, carrying out first cold drawing, carrying out second cold drawing, straightening, carrying out heat treatment on a finished product, straightening and carrying out blanking measurement;
the first cold drawing:
the inner die (1) and the outer die (2) are installed on cold-drawing equipment, and an inner die sizing belt (1-1) at the rear end of the inner die (1) extends out of an outer die sizing belt (2-1) at the rear end of the outer die (2) by 5-30 mm; carrying out primary cold drawing on the blank;
and the second cold drawing:
adjusting the inner die (1) to enable the rear ends of the inner die sizing belt (1-1) and the outer die sizing belt (2-1) to be aligned; and carrying out secondary cold drawing on the blank.
2. The method for manufacturing the large-caliber high-strength thick-wall cold drawn pipe according to claim 1, wherein the method comprises the following steps: an inner die tapered reducing belt (1-2) is arranged on the front side of the inner die sizing belt (1-1) on the outer peripheral surface of the inner die (1); the front side of the outer die sizing belt (2-1) on the inner peripheral surface of the outer die (2) is provided with an outer die tapered reducing belt (2-2).
3. The method for manufacturing the large-caliber high-strength thick-wall cold drawn pipe according to claim 1, wherein the method comprises the following steps: the inner die sizing belt (1-1) and the outer die sizing belt (2-1) are equal in length.
4. The method for manufacturing the large-caliber high-strength thick-wall cold drawn pipe according to claim 1, wherein the method comprises the following steps: and during the first cold drawing and the second cold drawing, after the inner die (1), the outer die (2) and the blank are arranged on the cold drawing equipment, the end part of the blank is extruded into the inner die (1) and the outer die (2) through the extruding head device.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910732626.4A CN110314951B (en) | 2019-08-09 | 2019-08-09 | Method for manufacturing large-caliber high-strength thick-wall cold drawn pipe |
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| CN201910732626.4A CN110314951B (en) | 2019-08-09 | 2019-08-09 | Method for manufacturing large-caliber high-strength thick-wall cold drawn pipe |
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| CN110314951A CN110314951A (en) | 2019-10-11 |
| CN110314951B true CN110314951B (en) | 2020-08-04 |
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| CN112058930B (en) * | 2020-08-18 | 2021-06-29 | 浙江大学 | A terrace die and supporting production facility structure for drawing eccentric blank pipe |
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| JP2003112218A (en) * | 2001-09-28 | 2003-04-15 | Usui Internatl Ind Co Ltd | Method for manufacturing thick-wall thin-diameter tube |
| CN100500316C (en) * | 2007-09-17 | 2009-06-17 | 江晓东 | Cold drawing accurate steel tube wall thickness adjusting mechanism |
| CN102189139A (en) * | 2011-03-23 | 2011-09-21 | 常州瑞源钢管有限公司 | Cold-drawing inner mold regulating and positioning device for internal-thread seamless steel pipe |
| CN102632093B (en) * | 2012-04-01 | 2014-11-26 | 徐州徐工液压件有限公司 | Steel pipe cold-drawing mould with twice-reducing and twice-shaping functions |
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