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
framework | Roller size | Ratio of speed | Rotary speed of roll r/min |
|||||||
Maximum outside diameter mm | Minimum outside diameter mm |
Inside diameter mm |
width mm |
type | power kW |
Rotary speed r/min |
||||
15H | 285 | 255 | 160 | 95/70 | DC | 450 | 0/600/1200 | 1.5 | 247~476 | |
16V | 285 | 255 | 160 | 95/70 | DC | 450 | 0/600/1200 | 1.24 | 314~606 | |
17H | 285 | 255 | 160 | 95/70 | DC | 450 | 0/600/1200 | 1.25 | 407~782 | |
18V | 285 | 255 | 160 | 95/70 | DC | 450 | 0/600/1200 | 0.94 | 500~1001 |
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
Worm Gear Motors
Worm gear motors are often preferred for quieter operation because of the smooth sliding motion of the worm shaft. Unlike gear motors with teeth, which may click as the worm turns, worm gear motors can be installed in a quiet area. In this article, we will talk about the CZPT whirling process and the various types of worms available. We’ll also discuss the benefits of worm gear motors and worm wheel.
worm gear
In the case of a worm gear, the axial pitch of the ring pinion of the corresponding revolving worm is equal to the circular pitch of the mating revolving pinion of the worm gear. A worm with 1 start is known as a worm with a lead. This leads to a smaller worm wheel. Worms can work in tight spaces because of their small profile.
Generally, a worm gear has high efficiency, but there are a few disadvantages. Worm gears are not recommended for high-heat applications because of their high level of rubbing. A full-fluid lubricant film and the low wear level of the gear reduce friction and wear. Worm gears also have a lower wear rate than a standard gear. The worm shaft and worm gear is also more efficient than a standard gear.
The worm gear shaft is cradled within a self-aligning bearing block that is attached to the gearbox casing. The eccentric housing has radial bearings on both ends, enabling it to engage with the worm gear wheel. The drive is transferred to the worm gear shaft through bevel gears 13A, 1 fixed at the ends of the worm gear shaft and the other in the center of the cross-shaft.
worm wheel
In a worm gearbox, the pinion or worm gear is centered between a geared cylinder and a worm shaft. The worm gear shaft is supported at either end by a radial thrust bearing. A gearbox’s cross-shaft is fixed to a suitable drive means and pivotally attached to the worm wheel. The input drive is transferred to the worm gear shaft 10 through bevel gears 13A, 1 of which is fixed to the end of the worm gear shaft and the other at the centre of the cross-shaft.
Worms and worm wheels are available in several materials. The worm wheel is made of bronze alloy, aluminum, or steel. Aluminum bronze worm wheels are a good choice for high-speed applications. Cast iron worm wheels are cheap and suitable for light loads. MC nylon worm wheels are highly wear-resistant and machinable. Aluminum bronze worm wheels are available and are good for applications with severe wear conditions.
When designing a worm wheel, it is vital to determine the correct lubricant for the worm shaft and a corresponding worm wheel. A suitable lubricant should have a kinematic viscosity of 300 mm2/s and be used for worm wheel sleeve bearings. The worm wheel and worm shaft should be properly lubricated to ensure their longevity.
Multi-start worms
A multi-start worm gear screw jack combines the benefits of multiple starts with linear output speeds. The multi-start worm shaft reduces the effects of single start worms and large ratio gears. Both types of worm gears have a reversible worm that can be reversed or stopped by hand, depending on the application. The worm gear’s self-locking ability depends on the lead angle, pressure angle, and friction coefficient.
A single-start worm has a single thread running the length of its shaft. The worm advances 1 tooth per revolution. A multi-start worm has multiple threads in each of its threads. The gear reduction on a multi-start worm is equal to the number of teeth on the gear minus the number of starts on the worm shaft. In general, a multi-start worm has 2 or 3 threads.
Worm gears can be quieter than other types of gears because the worm shaft glides rather than clicking. This makes them an excellent choice for applications where noise is a concern. Worm gears can be made of softer material, making them more noise-tolerant. In addition, they can withstand shock loads. Compared to gears with toothed teeth, worm gears have a lower noise and vibration rate.
CZPT whirling process
The CZPT whirling process for worm shafts raises the bar for precision gear machining in small to medium production volumes. The CZPT whirling process reduces thread rolling, increases worm quality, and offers reduced cycle times. The CZPT LWN-90 whirling machine features a steel bed, programmable force tailstock, and five-axis interpolation for increased accuracy and quality.
Its 4,000-rpm, 5-kW whirling spindle produces worms and various types of screws. Its outer diameters are up to 2.5 inches, while its length is up to 20 inches. Its dry-cutting process uses a vortex tube to deliver chilled compressed air to the cutting point. Oil is also added to the mixture. The worm shafts produced are free of undercuts, reducing the amount of machining required.
Induction hardening is a process that takes advantage of the whirling process. The induction hardening process utilizes alternating current (AC) to cause eddy currents in metallic objects. The higher the frequency, the higher the surface temperature. The electrical frequency is monitored through sensors to prevent overheating. Induction heating is programmable so that only certain parts of the worm shaft will harden.
Common tangent at an arbitrary point on both surfaces of the worm wheel
A worm gear consists of 2 helical segments with a helix angle equal to 90 degrees. This shape allows the worm to rotate with more than 1 tooth per rotation. A worm’s helix angle is usually close to 90 degrees and the body length is fairly long in the axial direction. A worm gear with a lead angle g has similar properties as a screw gear with a helix angle of 90 degrees.
The axial cross section of a worm gear is not conventionally trapezoidal. Instead, the linear part of the oblique side is replaced by cycloid curves. These curves have a common tangent near the pitch line. The worm wheel is then formed by gear cutting, resulting in a gear with 2 meshing surfaces. This worm gear can rotate at high speeds and still operate quietly.
A worm wheel with a cycloid pitch is a more efficient worm gear. It reduces friction between the worm and the gear, resulting in greater durability, improved operating efficiency, and reduced noise. This pitch line also helps the worm wheel engage more evenly and smoothly. Moreover, it prevents interference with their appearance. It also makes worm wheel and gear engagement smoother.
Calculation of worm shaft deflection
There are several methods for calculating worm shaft deflection, and each method has its own set of disadvantages. These commonly used methods provide good approximations but are inadequate for determining the actual worm shaft deflection. For example, these methods do not account for the geometric modifications to the worm, such as its helical winding of teeth. Furthermore, they overestimate the stiffening effect of the gearing. Hence, efficient thin worm shaft designs require other approaches.
Fortunately, several methods exist to determine the maximum worm shaft deflection. These methods use the finite element method, and include boundary conditions and parameter calculations. Here, we look at a couple of methods. The first method, DIN 3996, calculates the maximum worm shaft deflection based on the test results, while the second one, AGMA 6022, uses the root diameter of the worm as the equivalent bending diameter.
The second method focuses on the basic parameters of worm gearing. We’ll take a closer look at each. We’ll examine worm gearing teeth and the geometric factors that influence them. Commonly, the range of worm gearing teeth is 1 to four, but it can be as large as twelve. Choosing the teeth should depend on optimization requirements, including efficiency and weight. For example, if a worm gearing needs to be smaller than the previous model, then a small number of teeth will suffice.