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Steel rolling basics Q&A –part I

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1. What preparations should be done before rolling?

In the production of each product, preparations should be made starting from the roll change. In order to ensure the normal operation of rolling production, the position of the rolls, the main and auxiliary components of the rolling mill and related equipment must be checked before rolling. The structure of the rolling mill is different, and the items that need to be checked are also different. Generally, the items that must be checked are:

1) Roll: Consider the position of the roll after the roll jump;

2) Rolling mill components: Check various rolling mill components according to the technical regulations;

3) Rolling mill accessories: Check the rolling mill accessories according to technical specifications and practical experience;

4) Auxiliary equipment: Make sure that the auxiliary equipment is correct.

2. What are the precautions for trial rolling?

1) According to the main motor starting operation management system and rolling mill operation technical operation rules, notify all relevant posts to achieve safe starting and safe operation.

2) Supply cooling water before operation, after a period of idling, check whether the rolling mill is running normally, check whether the temperature rise of various bearings is normal, and see if there is any abnormal phenomenon of overheating and deformation.

3) Prepare the test rolling material in advance, tap the steel at a slow speed, and do not roll the rolling stock below the specified temperature, so as not to cause the main motor to trip or the safety device to be damaged.

4) In the process of trial rolling, measure the size of each red billet, and check whether the size is correct and the surface quality is good according to the adjustment icon. Only after the trial rolling is qualified can it enter into normal production.

3. What is the mainframe of the rolling mills? What equipment does it consist of?

The mechanical equipment of the rolling workshop can be divided into main equipment and auxiliary equipment according to their different roles in production. The part of the equipment that is used to make the metal beat the stars in the rotating rolls is usually the main equipment. The operation line formed by the main equipment is called the main line of the rolling mill. The main equipment of the rolling mill consists of one or several main engine columns. The host train consists of three parts: the main motor, the rolling mill and the transmission machinery. A rolling mill is generally composed of rolls, stands, roll adjustment devices, roll balance positions, and roll bearings. The function of the transmission device is to transmit the power of the motor to the roll, and its composition is related to the type and working system of the rolling mill. In many rolling mills, the transmission is composed of reducers, gear seats, connecting shafts and couplings, and sometimes flywheels.

The main motor is the equipment that powers the rotation of the rolls. In the rolling process, the rolling mill that does not need speed regulation is usually driven by AC motor, double differential speed regulation and AC frequency conversion speed regulation technology. The DC motor works flexibly and has a wide range of speed regulation, but the cost is much higher than that of the AC motor.rolling mill price -Juxinde

4. What connection devices does the rolling mills have?

The connecting shaft is a device that transmits power from the gear seat to the rolls, or from the rolls of one rolling mill to the rolls of another rolling mill, or directly from the main motor to the rolls. There are two types of universal connecting shafts: universal joint shaft and plum blossom joint shaft.

All roll diameters have a certain range of variation. From the installation of a new roll to the scrapping of the roll, the axis position of the roll should change up and down, while the axis of the herringbone gear in the gear seat is unchanged. The universal joint shaft allows the axis of the roll to have a large inclination angle (8-10°C) to the axis of the herringbone gear, which can smoothly transmit the torsional moment. The allowable inclination angle of the plum-blossom shaft is only 1-2 degrees, which is only suitable for rolling mills where the distance between the center lines of the work rolls does not change much. It is easy to disassemble and easy to change rollers.

The plum blossom joint shaft and plum blossom bushing should be adapted to the size of the roll journal, so that it can be disassembled when the roll is changed, bear a large impact load and prolong the service life. The shaft sleeve is generally made of cast iron, and it is made of cast steel under heavy stress. The section steel rolling mill with a roll diameter greater than 500mm has a large weight of the connecting shaft and the shaft sleeve. In order to prevent the weight of the plum blossom joint shaft and the universal joint shaft from acting on the hinge of the plum blossom shaft sleeve or the universal joint shaft, it is usually used in the connecting shaft. A connecting shaft bracket is installed in the middle to balance the weight of the connecting shaft and make the connecting shaft rotate smoothly.

Due to the advantages and disadvantages of the plum blossom joint and the universal joint, a joint joint has recently appeared, that is, a universal joint is used at the end of the connection between the shaft and the gear seat, and the end of the connection with the roll is connected with a universal joint. Plum joint shaft connection. In addition, there are arc gear shafts and so on.

5. What are the common rack forms?

Open type, closed type and semi-closed type.

The open frame is composed of a frame base and an upper beam. The advantages are simple manufacture, convenient loading and unloading, and convenient roll change. The disadvantage is that the strength and stiffness are low, and the roll jump value is large.

Due to the variety and specifications of section steel, most section steel rolling mills, especially small and medium-sized rolling mills, use open type rolling mills.

The closed frame is made of an integral casting, which has the advantages of high strength and rigidity, high rolling pressure or strict requirements on the size of the rolling stock, such as blooming mill, steel plate rolling mill, cold rolling machine, etc.

A diagonal connection is used between the semi-closed rack and the rack cover. It combines the advantages of both open and closed racks, and is convenient for loading and unloading, roll changing, easy to manufacture, and has greater rigidity. Generally, large and medium-sized steel rolling mills use this form of rack.

In addition to the above-mentioned types, there is also a no-paifang rolling mill, which has the advantages of light weight, good rigidity, high rolling precision, and convenient adjustment and operation.

6. What is a short stress line mill? What is a no-paifang mill?

The internal force caused by the rolling force during the rolling process of the rolling mill is the profit loop that is distributed along the bearing parts of the stand, referred to as the stress line. In order to improve the stiffness of the rolling mill, the rolling mill that shortens the stress line by various technical measures is the short stress line rolling mill. The short stress line mill is a high stiffness mill.

The short stress line rolling mill cancels the long stress member frame in the ordinary rolling mill, and two tension bolts on each side of the roll fix the two very rigid bearing seats together, which greatly shortens the rolling mill stress loop length, so that the rolling mill has greater rigidity.

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