How did the formula for calculating the elongation coefficient of steel pipe perforation evolve?

Small: Large, Medium, Small Deformation Theory of Cross Piercing Process on diagonal piercing (see Tube Blank Perforation) kinematics, bite intake, metal deformation and flow, stress and strain fractions.

(3) Seamless steel pipes with high dimensional accuracy and high surface roughness are suitable for mechanical structures and hydraulic equipment. Calculate the elongation coefficient of each pass of the steel pipe, and the elongation coefficient shall not exceed [. At the time of pulling, I do.

Pull-out elongation coefficient = s1 (d1-s1) s2 ( d2-s2).

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This question seems a bit incomplete, do you want to ask the finished pass or?

What is the elongation factor and how is it calculated?

The elongation coefficient refers to the ratio of the length of the capillary tube to the length of the tube blank, or the ratio of the cross-sectional area of the tube blank to the cross-sectional area of the capillary, that is:

l wool l blank = f blank f hair.

The formula for calculating the elongation factor is:

k*d2 billet 4*(d hair-s hair)*s hair.

Note: K - burn loss coefficient, generally taken, the burn loss coefficient of the annular furnace is generally D blank, D hair, S hair - tube blank diameter, capillary diameter and wall thickness elongation coefficient is large, indicating that the wall thickness of the capillary is thin, and the wall thickness of the capillary of the general small perforator is 8mm, and the minimum wall thickness of the capillary of the unit above 140 can reach 8mm.

1. Hot rolled pipe.

The uneven wall thickness is mainly due to a single perforation in hot rolling.

The uneven wall thickness of the capillary perforation may be caused by the following three factors.

1. The tube blank is heated unevenly, which is usually called the yin and yang face.

When the tube blank is heated in the inclined hearth furnace, the material is not diligent, which will cause half of the tube blank to be "cooked" and half to be "raw", and the resistance is different when perforating, resulting in uneven wall thickness.

2. The influence of the shape and position of the head.

The head is overused, and the "table" is accumulated by local melting, and the height of the "platform" is uneven, which is equivalent to the head is not round, which will affect the uneven wall thickness; In severe cases, it can also scratch the inner surface of the capillary, causing internal "heavy skin".

After the head position, it will also affect the uniformity of the wall thickness.

3. The ejector rod is shaken.

The centering roller of the perforator is not adjusted in place, and it cannot "hold" the ejector rod stably, and the ejector rod jumps, resulting in uneven wall thickness.

2. Cold drawing.

Causes of uneven thickness of cold-drawn seamless pipes:

1) The cutting slope and bending of the front end of the tube blank are too large, and the centering hole of the tube blank is not correct, which is easy to cause the uneven wall thickness of the steel pipe head.

2) The elongation coefficient is too large, the roll speed is too high, and the rolling is unstable.

3) The steel polishing of the perforator is unstable, which is easy to cause uneven wall thickness at the end of the capillary.

There are three types of tube blank perforation methods: pressure punching, oblique rolling perforation and push rolling perforation.

Pressure punching is all about punching holes in a press. The heated billet or ingot is first loaded into a circular die, and then the press drives a punch bar with a punch to punch a round hole in the central part of the tube blank. The gap between the billet or round billet and the circular die that is just filled by the metal extruded in the center is very small, and the maximum elongation coefficient does not exceed.

According to the number of rolls, diagonal piercing can be divided into two-high oblique rolling perforation and three-high diagonal rolling perforator. According to the shape of the roll, it is divided into disc perforator, conical roll perforator and barrel roll perforator.

The push rolling perforator method is an improvement of pressure punching. The fixed conical die is replaced by a pair of rolls with a round hole type. The pair of rolls is rotated by an electric motor, and the rotating rolls bite the tube blank into the hole shape of the roll, and the punch fixed to the hole pattern pierces a round hole in the center of the tube blank.

In order to facilitate rolling, a push-back hydraulic cylinder is added at the tail end of the tube blank, so it is called push-rolling perforation. This type of perforator uses a billet, and the capillary that is pierced is shorter, and the elongation coefficient is not greater than.

Among the above-mentioned three perforation methods, oblique rolling perforation is the most widely used in the production of seamless steel pipes.

(;Calculation formula:w=Where: w--- steel pipe unit weight, kg m;

d--- Specified outer diameter of steel pipe, mm;

S--- specified wall thickness of steel pipe, mm;

The coefficient that applies to the case where the density of the steel is.

No. 45 seamless steel pipe is made of steel ingots or solid pipe blanks perforated into capillaries, and then made by hot rolling, cold rolling or cold dialing, 45 seamless steel pipe is a material in steel, which is a high-quality carbon structural steel, and a large number of mold production companies will use it to make die steel. No. 45 seamless steel pipe has an important position in China's steel pipe industry. Formula for calculating the weight of seamless steel pipes:

Outer diameter - wall thickness) * wall thickness] * meters (weight per meter).

Round steel - into the furnace - firing - out of the furnace - perforating machine perforation - rolling mill rolling - sizing machine sizing - cooling bed cooling - straightening machine straightening - sawing head - baling.

Tube blank preparation - heating - perforation - capillary - pickling - cold rolling or cold drawing - annealing - straightening - cutting head - baling - marking and warehousing.

60mm round steel blanking, heating, perforation to 63*4, straightening flat head, pickling phosphating saponification drying, LGK-60 rolling to 48*, degreasing cleaning, heat treatment, straightening flat head.