阅读说明：本技术 一种用于穿孔的顶杆及该顶杆的制备方法 (Ejector rod for perforation and preparation method of ejector rod ) 是由 周维华 何新田 曹玉鑫 吴虎 张万超 李永灯 黎福华 周立新 杜坤 于 2020-12-23 设计创作，主要内容包括：本发明提供一种用于穿孔的顶杆及该顶杆的制备方法,所述顶杆的尺寸具体如下：外径D为102mm、壁厚h为22mm、内径d为58mm。与现有的顶杆相比,该发明提供的顶杆抗弯强度更好,且通过制备工艺改进,顶杆的直度更好,该发明能够有效地解决穿孔后毛管壁厚不均的问题,从而达到减少钢管切头,提高成材率。(The invention provides a mandril for perforation and a preparation method thereof, wherein the mandril has the following dimensions: the outer diameter D was 102mm, the wall thickness h was 22mm and the inner diameter D was 58 mm. Compared with the existing ejector rod, the ejector rod provided by the invention has better bending strength, and the straightness of the ejector rod is better through the improvement of the preparation process.)

1. A mandril for perforation is characterized in that,

the size of the ejector rod is as follows: the outer diameter D was 102mm, the wall thickness h was 22mm and the inner diameter D was 58 mm.

2. The ejector rod of claim 1, wherein the ejector rod is made of 1Cr5Mo, and the specific components of 1Cr5Mo are as follows by mass percent:

less than or equal to 0.15 percent of carbon, less than or equal to 0.50 percent of silicon, 0.30 to 0.60 percent of manganese, less than or equal to 0.025 percent of phosphorus, less than or equal to 0.025 percent of sulfur, 4.00 to 6.00 percent of chromium, 0.45 to 0.65 percent of molybdenum, and the balance of iron and inevitable impurities.

3. A method for producing a carrier rod according to any one of claims 1 to 2, comprising the steps of:

1) material lifting production: performing hot rolling production by using a rough steel pipe with the size of 108 × 25, wherein the length of the rough steel pipe is 1 meter more than that of the finished ejector rod;

2) peeling: and (3) carrying out centerless peeling on the rough steel pipe in the step 1) to reach a size of 102 × 22 finished ejector rods.

4. The production method according to claim 3,

in the step 2), the outer diameter D of the ejector rod is controlled within 102 +/-0.2 mm, the bending degree of the ejector rod is controlled within 0.5mm/m, and the total length is controlled within 3 mm.

5. The production method according to claim 3,

in the step 2), the iron oxide scale on the surface of the mandril is eliminated at the same time.

6. The production method according to claim 3,

in the step 1), the outer diameter of the rough steel pipe is 6mm larger than the outer diameter D of the ejector rod, so that the follow-up peeling processing has enough processing allowance.

7. The production method according to claim 3,

and the rough steel pipe is cooled in a natural air cooling mode after being hot-rolled.

8. The production method according to claim 3,

and after the rough steel pipe is produced by hot rolling, carrying out hot straightening or pressing straightening again to ensure that the rough steel pipe has better original straightness and the bending is controlled within 1 mm/m.

9. The production method according to claim 3,

the material of ejector pin is 1Cr5Mo, the material state of ejector pin is the hot rolling state.

Technical Field

The invention belongs to the field of manufacturing of special steel equipment, and particularly relates to a mandril for perforation and a preparation method of the mandril.

Background

The ejector rod is used as a key tool of the perforating machine, and is subjected to a large axial force when the perforation deforms, and when the bending strength of the ejector rod is insufficient, the quality problem of eccentricity of the wall thickness of the steel pipe is easily caused. The reason for causing the eccentricity of the wall thickness of the steel pipe is that the ejector rods are embraced by a plurality of groups of three-roller centering embrace rollers at the perforation background when the capillary tube does not arrive, the capillary tube is properly opened (opened slightly) to embrace the capillary tube when the capillary tube penetrates, the force arm of the ejector rods is increased at the moment, and if the rigidity of the ejector rods is insufficient, the ejector rods are bent, so that the ejector heads are not centered, and the steel pipe is thick on one side and thin on the other side. Due to the automatic centering function of the perforation, the eccentricity is gradually improved to be normal, and the eccentricity occurs when the next holding roller is opened slightly, so that the periodical and discontinuous eccentricity occurs. Meanwhile, the straightness of the ejector rod is poor, the ejector rod shakes during punching, the ejector head is not centered, and the wall thickness of the steel pipe is eccentric.

Disclosure of Invention

The invention aims to provide a mandril for perforation and a preparation method thereof, the mandril provided by the invention has better bending strength (compared with the existing mandril), and the straightness of the mandril is better through the improvement of the preparation process, and the invention can effectively solve the problem of uneven wall thickness of a perforated capillary tube, thereby reducing the cut end of a steel tube and improving the yield.

In order to achieve the above purpose, the invention provides the following technical scheme:

a mandrel for perforation, the mandrel having the following dimensions: the outer diameter D was 102mm, the wall thickness h was 22mm and the inner diameter D was 58 mm.

Further, in the ejector rod, the material of the ejector rod is 1Cr5Mo, and the specific components of 1Cr5Mo are shown in mass percent as follows:

less than or equal to 0.15 percent of carbon, less than or equal to 0.50 percent of silicon, 0.30 to 0.60 percent of manganese, less than or equal to 0.025 percent of phosphorus, less than or equal to 0.025 percent of sulfur, 4.00 to 6.00 percent of chromium, 0.45 to 0.65 percent of molybdenum, and the balance of iron and inevitable impurities.

In another aspect, a method for preparing the mandrel comprises the following steps:

1) material lifting production: performing hot rolling production by using a rough steel pipe with the size of 108 × 25, wherein the length of the rough steel pipe is 1 meter more than that of the finished ejector rod;

2) peeling: and (3) carrying out centerless peeling on the rough steel pipe in the step 1) to reach a size of 102 × 22 finished ejector rods.

Further, in the above preparation method, in the step 2), the outer diameter D of the ejector pin is controlled within 102 ± 0.2mm, the bending degree of the ejector pin is controlled within 0.5mm/m, and the total length is controlled within 3 mm.

Further, in the above preparation method, in the step 2), the scale on the surface of the lift pin is simultaneously removed.

Further, in the above preparation method, in the step 1), the outer diameter of the blank steel pipe is 6mm larger than the outer diameter D of the mandrel, so as to ensure that the subsequent peeling process has a sufficient process margin.

Further, in the above production method, the raw steel pipe is cooled by natural air cooling after hot rolling.

Further, in the above preparation method, the blank steel pipe is hot-straightened or is further press-straightened after hot rolling production to ensure better original straightness, and the bending is controlled within 1 mm/m.

Further, in the above manufacturing method, the material of the lift pin is 1Cr5Mo, and the material state of the lift pin is a hot rolled state.

The analysis shows that the ejector rod for perforation and the preparation method of the ejector rod are better in bending strength compared with the existing ejector rod, the straightness of the ejector rod is better through the improvement of the preparation process, and the problem that the wall thickness of a perforated capillary tube is uneven can be effectively solved, so that the end cutting of a steel tube is reduced, and the yield is improved.

Detailed Description

The present invention will be described in detail with reference to examples. The various examples are provided by way of explanation of the invention, and not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment, can be used with another embodiment to yield a still further embodiment. It is therefore intended that the present invention encompass such modifications and variations as fall within the scope of the appended claims and equivalents thereof.

According to the embodiment of the invention, the ejector rod for perforation is provided, the ejector rod bears the pressure and the torsion force transmitted by the ejector head in the working process, and the pressure can cause unstable influence on the ejector rod mainly in the uniform perforation process.

The ejector rod is a hollow steel pipe. The ejector rod is used as a slender rod piece, the length L is far greater than the interface height (wall thickness) h, namely L>>h, the maximum bending positive stress is much greater than the bending shear stress. According to the bending normal stress intensity conditionThe bending resistance section coefficient W can be known from the formula (1)_zThe larger the pressure, the more stable the pressure can be. In the formula: sigma_maxMaximum normal stress strength (bending strength) of cross section (N/m) that can be borne by finger²) M denotes the bending moment (N M), W to which the rod is subjected_zBending resistance section modulus (m) of finger member³)，[σ]The section that the finger rod can bear allows normal stress (strength) (N/m)²). The bending section coefficient is used as the denominator of the formula to directly influence the bending strength.

The commonly used sizes of the plug in the prior art are phi 102mm, phi 105mm and phi 108 mm. The size of the existing ejector rod: the outer diameter D is 89mm, the wall thickness h is 16mm and the inner diameter D is 57 mm. According to the design specification, the diameter of the existing ejector rod is generally 2 mm-15 mm smaller than that of the ejector head, and the diameter range of the ejector rod is phi 87 mm-phi 100 mm.

The front part of the ejector rod is adopted to process an inclined plane, the inclined plane is 400mm long, the front end is small by 4mm (single side), the diameter of the ejector rod is equal to that of the ejector head, and the condition that the capillary is scratched is normally used on trial. Bending resistance section modulusFormula (2) for increasing W_zAnd (4) checking the backwater of the ejector rod by selecting the large outer diameter D of the ejector rod as far as possible and selecting the outer diameter D as 102 mm. A water inlet pipe is arranged in the ejector rod and serves as a cooling water pipe to realize water cooling in the ejector head, the gap area between the ejector rod and the cooling water pipe must be larger than 1.2 times (preferably 1.2-1.5 times) of the area of the inner cavity of the cooling water pipe, and the backwater of the ejector rod meets the requirement. And after checking the backwater of the ejector rod, determining the inner diameter d of the ejector rod to be 58mm, and calculating the wall thickness of the ejector rod to be 22 mm. The bending strength can be calculated by the formula (1). The bending section coefficient is used as the denominator of the formula to directly influence the bending strength.

In the invention, the size of the ejector rod is optimized and improved by increasing the diameter and the wall thickness of the ejector rod, and the size of the ejector rod in the invention is determined as follows: the outer diameter D was 102mm, the wall thickness h was 22mm and the inner diameter D was 58 mm. In the prior art, the inner wall of the capillary tube at the front part of the ejector rod is smaller, so that the backwater and the like of the ejector rod are limited, the size design breaks through the limitation, and the bending-resistant section coefficient is unexpectedly improved. Bending resistance section modulusChanges were made as shown in table 1 below.

TABLE 1 bending resistance section modulus of ejector pin (Steel pipe)

As can be seen from Table 1, the bending resistance section modulus W of the ejector pin of the present invention_zIncreased by 62%, increasedThe addition range is large, and the unexpected technical effect is achieved. If the diameter is larger than the size of the present application (the outer diameter D is 102mm, the wall thickness h is 22mm, and the inner diameter D is 58mm), the inner cavity of the capillary tube will be scraped at the front part of the carrier rod, and if the diameter is smaller than the size of the present application, the bending strength will not be improved to the utmost.

The invention also provides a preparation method of the ejector rod, which comprises the following process steps:

1) material lifting production: the production is carried out by using a rough steel pipe with the size of 108 × 25, and the length of the rough steel pipe is 1 meter more than that of a finished product of the ejector rod, namely, the amount of 1 meter of end cutting is increased. The outer diameter of the rough steel pipe is 6mm larger than the outer diameter D of the ejector rod, so that sufficient machining allowance is ensured for subsequent peeling machining. The length of the rough steel pipe is 1 meter, so that enough cutting allowance of sections with poor uniformity of wall thickness at two ends is guaranteed. And after the steel pipe is hot-rolled, a natural air cooling mode is adopted. After the steel pipe is produced by hot rolling, the steel pipe is thermally straightened or is pressed and straightened again to ensure better original straightness, and the bending of the steel pipe is controlled within 1 mm/m.

The material of the carrier rod is preferably 1Cr5Mo, and the material state of the carrier rod is a hot-rolled state.

2) Peeling: and (3) machining the rough steel pipe in the step 1) to 102 × 22 finished ejector rod size by adopting centerless peeling. The centreless peeling processing is convenient for processing the long rod piece, the ovality of the steel pipe is eliminated, the roundness of the steel pipe is better, the outer diameter D of the ejector rod can be controlled within 102 +/-0.2 mm, the iron scale on the surface of the steel pipe is eliminated, and the surface quality is good.

On the other hand, the centerless peeling processing is adopted, so that the bending degree in a hot rolling straightening state is effectively eliminated, and the bending control of the ejector rod is ensured to be within 0.5mm/m and within 3mm of the total length. The bending of the push rod in the prior hot rolling straightening state can be controlled within 1mm/m and 5mm of the total length.

The materials of the large and small push rods in the existing push rods are all made of 42CrMo materials and are subjected to quenching and tempering treatment. The quenching and tempering process of the 42CrMo ejector rod comprises the following steps: quenching in water at 830-850 deg.C, and tempering at 600-650 deg.C to obtain the tempered sorbite structure.

The material of the ejector rod is optimized from 42CrMo to 1Cr5Mo, and the components and the performance characteristics of the two materials are shown in Table 2.

Performance characteristics of Table 242 CrMo and 1Cr5Mo

Comparison of high temperature properties of 42CrMo and 1Cr5 Mo:

the ejector rod usually works at the temperature of about 300 ℃ (ejector rod temperature), bears the larger pressure and torsional force transmitted by the ejector head, has worse working conditions, better ensures the rigidity, and has higher requirements on the heat resistance and heat strength of materials.

Bending deformation removing and bending-resistant section coefficient W_zIn addition, the strength of each material in a high temperature state differs depending on the actual state of the hole although the elastic modulus of each steel material is substantially the same as the deformation is smaller as the elastic modulus E of the material is larger. The material of the ejector rod is preferably heat-resistant and high-strength. The comparison of the high-temperature properties of 42CrMo and 1Cr5Mo is shown in Table 3, and the quenching and tempering process of the 42CrMo mandril is as follows: quenching in water at 830-850 deg.C, and tempering at 600-650 deg.C to obtain the tempered sorbite structure.

TABLE 342 comparison of the high temperature Performance of CrMo and 1Cr5Mo

The difference of the processing process of the hot rolling state and the quenching and tempering state is as follows: and after hot rolling in a hot rolling state, the steel is directly and naturally cooled down in the air, and quenching and high-temperature tempering are carried out in a quenching and tempering state.

The main advantages of 1Cr5Mo compared to 42CrMo are as follows:

1) has better heat strength below 660 ℃, better oxidation resistance at about 650 ℃, small reduction amplitude (5%) of high strength still maintained at 300 ℃, 14% higher strength than 42CrMo at normal temperature and about 30% higher strength than 42CrMo at 300 ℃.

2) The high-temperature performance is more stable, the reduction amplitude of the elastic modulus E at 300 ℃ is small (2 percent) and is higher than 18 percent of that of 42 CrMo.

The performance hot rolled state of the 1Cr5Mo can meet the requirements, and tests and analysis carried out by the inventor show that the strength of the 1Cr5Mo quenched and tempered state is not increased, so that the 1Cr5Mo only needs to be in a hot rolled state, and the procedure and the cost are saved.

When the method is applied to the online production of four core rod series, the end cutting length is reduced, and the yield is improved. The cutting loss is reduced from 10.5 percent to 7.73 percent, and the cutting loss is reduced by 2.77 percent; the yield is improved from 84.11% to 88.87%, the yield is improved by 4.76%, and remarkable economic benefit is achieved.

From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:

the following method for strengthening the rigidity of the carrier rod has been developed through intensive internal state analysis and the like. Because the bending deformation of the ejector rod is related to the bending section coefficient and the elastic modulus, the rigidity strengthening of the ejector rod comprises the steps of increasing the outer diameter and the wall thickness of the ejector rod to the maximum extent, synchronously achieving the purpose of good internal cooling water return water (ejector rod return water), and designing the size of the ejector rod; and selecting high-strength material at about 300 deg.C (push rod temperature) to improve the use strength of the push rod. Meanwhile, the hot rolling state of the ejector rod is changed into the peeling processing state, so that the straightness of the ejector rod is improved.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.