Product Description

Common technical processing overview
Continuous casting square billets —— Heating CZPT —- High pressure water CZPT —- Roughing mills group —– # 1 Flying Shears —- Intermediate mills group —– #2 Flying shears —– Finishing mills group —#3 multi-lengths flying shears  —- Step rack cooling bed—— Fixed length cold shears——- The finished product automatic counting and bundling — Storage.

The function of pre-finishing mill
In the process of high-speed wire-rod rolling, pre-finishing mill can improve the precision of the working piece to guarantee the product quality and avoid possible operation failure during the finishing mill section.The structure of framework
Its structure is 2 horizontal and 2 vertical (horizontal-vertical-horizontal-vertical; H-V-H-V) cantilever type, it is very compact, and the weight adjustment is more precise and reliable, and so to avoid possible twist rolling.
Pre-finishing mill is composed by 2 horizontal mills, 3 vertical loops, 2 vertical mills, safety cover and so on.Equipment structure
Transmission box
The role of transmission box is to transmit the moment outputted by reduction gear and motor to roll shafts. Horizontal box has a pair of cylindrical bevel gears; vertical box has a pair of additional spiral bevel gear beside a pair of cylindrical bevel gear. The spiral bevel gear speed ratio of the 2 vertical transmission boxes is different.
Roller box
Each roller box has 1 upper roll shaft and 1 lower roll shaft; they are not meshed, and driven by a pair of cylindrical bevel gears in the transmission box.
A cantilever cylindrical roll shaft is fixed to each roll shaft; the roll shaft is fixed in the eccentric locking collar and sustained by the front and rear film bearing. Driven by the left and right feed screw and nut of the shaft gap adjustment device, the eccentric locking collar makes the upper and lower roll shaft open and shut symmetrically and evenly relate to the milling centre line, in so to achieve roll shaft gap adjustment. The roll shafts are made of tungsten carbide.
The roller box is installed with flange in plug-in method,
and convenient to assembly and disassembly, the roller box and transmission box are individual unites, during the installation, assemble the roller box and transmission box at the first stage and then fix the roller box inside the transmission box with screw bolt, the roller box is positioned by 2 locating pins to obtain accurate position. In this way, the installation can be done easily and with a shorter time, meanwhile, the pipework on the panel is reduced and make it easier for failure handling. 1, The roller gap is adjusted by using the eccentric locking collar, by adjusting the lead screw and nut , the eccentric locking collar will spin and then drive the roller shaft to move symmetrically, in so to achieve the adjustment of roller shaft gap. The best advantage of this adjustment method is that the central line will be kept unchanged.
2, By using the thrust bearing that fixed at the end of the roller shaft, we can effectively prevent the axial shift of the roller shaft, in so to ensure size accuracy of the product.
3, the size and structure of the roller box for horizontal framework and vertical framework are the same, all the parts are interchangeable.
4, the power transmission and speed control are conducted by a pair of spiral bevel gears in the transmission box, the reducer is omitted from the transmission system of the vertical rolling mill, so that the whole equipment is lighter and smaller.
5. As the horizontal framework is completely symmetrical, it can be rotated 180, so it can be shared by 2 production lines that located at its right and left side.
Xihu (West Lake) Dis. device
The entrance of roller box has installed scroll CZPT and slip guide, the exit of roller box just has slip guide, slip CZPT is lubricated by special lubrication device.
Main technical features
First mill input specification: F28~F31mm
Fourth mill output specification: F16~F20mm
The kinds of rolling steel: Carbon steel, high carbon steel, low alloy steel, welding steel, heading steel.
The temperature of rolling: 900~1050ºC
Transmission method: Direct current (DC) motor alone drives
The transmission parameter table of pre-finishing mill

Maximum rolling strength: ~240kN
Maximum rolling moment: ~6.2kN·m
Centre distance of roll shaft: F255mm~F291mm
Adjustment of roller gap: ±18 mm
Cooling water of roll shaft: consumption: 4×20 t/h
water pressure 0.6MPa
temperature of water coming: <30ºC
(11)lubrication
Roller box and reduction equipment adopt thin oil to lubricate, which is offered by workshop.
Pressure of oil: pressure in lubrication point 0.15~0.25MPa
Total consumption: 400 l/min
Oiliness: Mobil 533
Refined filter: 25μ

What Are Screw Shaft Threads?

A screw shaft is a threaded part used to fasten other components. The threads on a screw shaft are often described by their Coefficient of Friction, which describes how much friction is present between the mating surfaces. This article discusses these characteristics as well as the Material and Helix angle. You’ll have a better understanding of your screw shaft’s threads after reading this article. Here are some examples. Once you understand these details, you’ll be able to select the best screw nut for your needs.

Coefficient of friction between the mating surfaces of a nut and a screw shaft

There are 2 types of friction coefficients. Dynamic friction and static friction. The latter refers to the amount of friction a nut has to resist an opposing motion. In addition to the material strength, a higher coefficient of friction can cause stick-slip. This can lead to intermittent running behavior and loud squeaking. Stick-slip may lead to a malfunctioning plain bearing. Rough shafts can be used to improve this condition.
The 2 types of friction coefficients are related to the applied force. When applying force, the applied force must equal the nut’s pitch diameter. When the screw shaft is tightened, the force may be removed. In the case of a loosening clamp, the applied force is smaller than the bolt’s pitch diameter. Therefore, the higher the property class of the bolt, the lower the coefficient of friction.
In most cases, the screwface coefficient of friction is lower than the nut face. This is because of zinc plating on the joint surface. Moreover, power screws are commonly used in the aerospace industry. Whether or not they are power screws, they are typically made of carbon steel, alloy steel, or stainless steel. They are often used in conjunction with bronze or plastic nuts, which are preferred in higher-duty applications. These screws often require no holding brakes and are extremely easy to use in many applications.
The coefficient of friction between the mating surfaces of t-screws is highly dependent on the material of the screw and the nut. For example, screws with internal lubricated plastic nuts use bearing-grade bronze nuts. These nuts are usually used on carbon steel screws, but can be used with stainless steel screws. In addition to this, they are easy to clean.

Helix angle

In most applications, the helix angle of a screw shaft is an important factor for torque calculation. There are 2 types of helix angle: right and left hand. The right hand screw is usually smaller than the left hand one. The left hand screw is larger than the right hand screw. However, there are some exceptions to the rule. A left hand screw may have a greater helix angle than a right hand screw.
A screw’s helix angle is the angle formed by the helix and the axial line. Although the helix angle is not usually changed, it can have a significant effect on the processing of the screw and the amount of material conveyed. These changes are more common in 2 stage and special mixing screws, and metering screws. These measurements are crucial for determining the helix angle. In most cases, the lead angle is the correct angle when the screw shaft has the right helix angle.
High helix screws have large leads, sometimes up to 6 times the screw diameter. These screws reduce the screw diameter, mass, and inertia, allowing for higher speed and precision. High helix screws are also low-rotation, so they minimize vibrations and audible noises. But the right helix angle is important in any application. You must carefully choose the right type of screw for the job at hand.
If you choose a screw gear that has a helix angle other than parallel, you should select a thrust bearing with a correspondingly large center distance. In the case of a screw gear, a 45-degree helix angle is most common. A helix angle greater than zero degrees is also acceptable. Mixing up helix angles is beneficial because it allows for a variety of center distances and unique applications.

Thread angle

The thread angle of a screw shaft is measured from the base of the head of the screw to the top of the screw’s thread. In America, the standard screw thread angle is 60 degrees. The standard thread angle was not widely adopted until the early twentieth century. A committee was established by the Franklin Institute in 1864 to study screw threads. The committee recommended the Sellers thread, which was modified into the United States Standard Thread. The standardized thread was adopted by the United States Navy in 1868 and was recommended for construction by the Master Car Builders’ Association in 1871.
Generally speaking, the major diameter of a screw’s threads is the outside diameter. The major diameter of a nut is not directly measured, but can be determined with go/no-go gauges. It is necessary to understand the major and minor diameters in relation to each other in order to determine a screw’s thread angle. Once this is known, the next step is to determine how much of a pitch is necessary to ensure a screw’s proper function.
Helix angle and thread angle are 2 different types of angles that affect screw efficiency. For a lead screw, the helix angle is the angle between the helix of the thread and the line perpendicular to the axis of rotation. A lead screw has a greater helix angle than a helical one, but has higher frictional losses. A high-quality lead screw requires a higher torque to rotate. Thread angle and lead angle are complementary angles, but each screw has its own specific advantages.
Screw pitch and TPI have little to do with tolerances, craftsmanship, quality, or cost, but rather the size of a screw’s thread relative to its diameter. Compared to a standard screw, the fine and coarse threads are easier to tighten. The coarser thread is deeper, which results in lower torques. If a screw fails because of torsional shear, it is likely to be a result of a small minor diameter.

Material

Screws have a variety of different sizes, shapes, and materials. They are typically machined on CNC machines and lathes. Each type is used for different purposes. The size and material of a screw shaft are influenced by how it will be used. The following sections give an overview of the main types of screw shafts. Each 1 is designed to perform a specific function. If you have questions about a specific type, contact your local machine shop.
Lead screws are cheaper than ball screws and are used in light-duty, intermittent applications. Lead screws, however, have poor efficiency and are not recommended for continuous power transmission. But, they are effective in vertical applications and are more compact. Lead screws are typically used as a kinematic pair with a ball screw. Some types of lead screws also have self-locking properties. Because they have a low coefficient of friction, they have a compact design and very few parts.
Screws are made of a variety of metals and alloys. Steel is an economical and durable material, but there are also alloy steel and stainless steel types. Bronze nuts are the most common and are often used in higher-duty applications. Plastic nuts provide low-friction, which helps reduce the drive torques. Stainless steel screws are also used in high-performance applications, and may be made of titanium. The materials used to create screw shafts vary, but they all have their specific functions.
Screws are used in a wide range of applications, from industrial and consumer products to transportation equipment. They are used in many different industries, and the materials they’re made of can determine their life. The life of a screw depends on the load that it bears, the design of its internal structure, lubrication, and machining processes. When choosing screw assemblies, look for a screw made from the highest quality steels possible. Usually, the materials are very clean, so they’re a great choice for a screw. However, the presence of imperfections may cause a normal fatigue failure.

Self-locking features

Screws are known to be self-locking by nature. The mechanism for this feature is based on several factors, such as the pitch angle of the threads, material pairing, lubrication, and heating. This feature is only possible if the shaft is subjected to conditions that are not likely to cause the threads to loosen on their own. The self-locking ability of a screw depends on several factors, including the pitch angle of the thread flank and the coefficient of sliding friction between the 2 materials.
One of the most common uses of screws is in a screw top container lid, corkscrew, threaded pipe joint, vise, C-clamp, and screw jack. Other applications of screw shafts include transferring power, but these are often intermittent and low-power operations. Screws are also used to move material in Archimedes’ screw, auger earth drill, screw conveyor, and micrometer.
A common self-locking feature for a screw is the presence of a lead screw. A screw with a low PV value is safe to operate, but a screw with high PV will need a lower rotation speed. Another example is a self-locking screw that does not require lubrication. The PV value is also dependent on the material of the screw’s construction, as well as its lubrication conditions. Finally, a screw’s end fixity – the way the screw is supported – affects the performance and efficiency of a screw.
Lead screws are less expensive and easier to manufacture. They are a good choice for light-weight and intermittent applications. These screws also have self-locking capabilities. They can be self-tightened and require less torque for driving than other types. The advantage of lead screws is their small size and minimal number of parts. They are highly efficient in vertical and intermittent applications. They are not as accurate as lead screws and often have backlash, which is caused by insufficient threads.