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
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.
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
|Ratio of speed
|Rotary speed of roll
|Maximum outside diameter mm
|Minimum outside diameter
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
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
How to Calculate the Diameter of a Worm Gear
In this article, we will discuss the characteristics of the Duplex, Single-throated, and Undercut worm gears and the analysis of worm shaft deflection. Besides that, we will explore how the diameter of a worm gear is calculated. If you have any doubt about the function of a worm gear, you can refer to the table below. Also, keep in mind that a worm gear has several important parameters which determine its working.
Duplex worm gear
A duplex worm gear set is distinguished by its ability to maintain precise angles and high gear ratios. The backlash of the gearing can be readjusted several times. The axial position of the worm shaft can be determined by adjusting screws on the housing cover. This feature allows for low backlash engagement of the worm tooth pitch with the worm gear. This feature is especially beneficial when backlash is a critical factor when selecting gears.
The standard worm gear shaft requires less lubrication than its dual counterpart. Worm gears are difficult to lubricate because they are sliding rather than rotating. They also have fewer moving parts and fewer points of failure. The disadvantage of a worm gear is that you cannot reverse the direction of power due to friction between the worm and the wheel. Because of this, they are best used in machines that operate at low speeds.
Worm wheels have teeth that form a helix. This helix produces axial thrust forces, depending on the hand of the helix and the direction of rotation. To handle these forces, the worms should be mounted securely using dowel pins, step shafts, and dowel pins. To prevent the worm from shifting, the worm wheel axis must be aligned with the center of the worm wheel’s face width.
The backlash of the CZPT duplex worm gear is adjustable. By shifting the worm axially, the section of the worm with the desired tooth thickness is in contact with the wheel. As a result, the backlash is adjustable. Worm gears are an excellent choice for rotary tables, high-precision reversing applications, and ultra-low-backlash gearboxes. Axial shift backlash is a major advantage of duplex worm gears, and this feature translates into a simple and fast assembly process.
When choosing a gear set, the size and lubrication process will be crucial. If you’re not careful, you might end up with a damaged gear or 1 with improper backlash. Luckily, there are some simple ways to maintain the proper tooth contact and backlash of your worm gears, ensuring long-term reliability and performance. As with any gear set, proper lubrication will ensure your worm gears last for years to come.
Single-throated worm gear
Worm gears mesh by sliding and rolling motions, but sliding contact dominates at high reduction ratios. Worm gears’ efficiency is limited by the friction and heat generated during sliding, so lubrication is necessary to maintain optimal efficiency. The worm and gear are usually made of dissimilar metals, such as phosphor-bronze or hardened steel. MC nylon, a synthetic engineering plastic, is often used for the shaft.
Worm gears are highly efficient in transmission of power and are adaptable to various types of machinery and devices. Their low output speed and high torque make them a popular choice for power transmission. A single-throated worm gear is easy to assemble and lock. A double-throated worm gear requires 2 shafts, 1 for each worm gear. Both styles are efficient in high-torque applications.
Worm gears are widely used in power transmission applications because of their low speed and compact design. A numerical model was developed to calculate the quasi-static load sharing between gears and mating surfaces. The influence coefficient method allows fast computing of the deformation of the gear surface and local contact of the mating surfaces. The resultant analysis shows that a single-throated worm gear can reduce the amount of energy required to drive an electric motor.
In addition to the wear caused by friction, a worm wheel can experience additional wear. Because the worm wheel is softer than the worm, most of the wear occurs on the wheel. In fact, the number of teeth on a worm wheel should not match its thread count. A single-throated worm gear shaft can increase the efficiency of a machine by as much as 35%. In addition, it can lower the cost of running.
A worm gear is used when the diametrical pitch of the worm wheel and worm gear are the same. If the diametrical pitch of both gears is the same, the 2 worms will mesh properly. In addition, the worm wheel and worm will be attached to each other with a set screw. This screw is inserted into the hub and then secured with a locknut.
Undercut worm gear
Undercut worm gears have a cylindrical shaft, and their teeth are shaped in an evolution-like pattern. Worms are made of a hardened cemented metal, 16MnCr5. The number of gear teeth is determined by the pressure angle at the zero gearing correction. The teeth are convex in normal and centre-line sections. The diameter of the worm is determined by the worm’s tangential profile, d1. Undercut worm gears are used when the number of teeth in the cylinder is large, and when the shaft is rigid enough to resist excessive load.
The center-line distance of the worm gears is the distance from the worm centre to the outer diameter. This distance affects the worm’s deflection and its safety. Enter a specific value for the bearing distance. Then, the software proposes a range of suitable solutions based on the number of teeth and the module. The table of solutions contains various options, and the selected variant is transferred to the main calculation.
A pressure-angle-angle-compensated worm can be manufactured using single-pointed lathe tools or end mills. The worm’s diameter and depth are influenced by the cutter used. In addition, the diameter of the grinding wheel determines the profile of the worm. If the worm is cut too deep, it will result in undercutting. Despite the undercutting risk, the design of worm gearing is flexible and allows considerable freedom.
The reduction ratio of a worm gear is massive. With only a little effort, the worm gear can significantly reduce speed and torque. In contrast, conventional gear sets need to make multiple reductions to get the same reduction level. Worm gears also have several disadvantages. Worm gears can’t reverse the direction of power because the friction between the worm and the wheel makes this impossible. The worm gear can’t reverse the direction of power, but the worm moves from 1 direction to another.
The process of undercutting is closely related to the profile of the worm. The worm’s profile will vary depending on the worm diameter, lead angle, and grinding wheel diameter. The worm’s profile will change if the generating process has removed material from the tooth base. A small undercut reduces tooth strength and reduces contact. For smaller gears, a minimum of 14-1/2degPA gears should be used.
Analysis of worm shaft deflection
To analyze the worm shaft deflection, we first derived its maximum deflection value. The deflection is calculated using the Euler-Bernoulli method and Timoshenko shear deformation. Then, we calculated the moment of inertia and the area of the transverse section using CAD software. In our analysis, we used the results of the test to compare the resulting parameters with the theoretical ones.
We can use the resulting centre-line distance and worm gear tooth profiles to calculate the required worm deflection. Using these values, we can use the worm gear deflection analysis to ensure the correct bearing size and worm gear teeth. Once we have these values, we can transfer them to the main calculation. Then, we can calculate the worm deflection and its safety. Then, we enter the values into the appropriate tables, and the resulting solutions are automatically transferred into the main calculation. However, we have to keep in mind that the deflection value will not be considered safe if it is larger than the worm gear’s outer diameter.
We use a four-stage process for investigating worm shaft deflection. We first apply the finite element method to compute the deflection and compare the simulation results with the experimentally tested worm shafts. Finally, we perform parameter studies with 15 worm gear toothings without considering the shaft geometry. This step is the first of 4 stages of the investigation. Once we have calculated the deflection, we can use the simulation results to determine the parameters needed to optimize the design.
Using a calculation system to calculate worm shaft deflection, we can determine the efficiency of worm gears. There are several parameters to optimize gearing efficiency, including material and geometry, and lubricant. In addition, we can reduce the bearing losses, which are caused by bearing failures. We can also identify the supporting method for the worm shafts in the options menu. The theoretical section provides further information.