A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a pipe or solid rod in the form of a helix, with the former being called a straight thread and the latter called a tapered thread. A screw thread is the essential feature of the thread rolling machine.
The mechanical advantage of a screw thread depends on its lead, which is the linear distance the screw travels in one revolution. In most applications, the lead of a screw thread is chosen so that friction is sufficient to prevent linear motion being converted to rotary, that is so the screw does not slip even when linear force is applied, as long as no external rotational force is present. This characteristic is essential to the vast majority of its uses.
Threading is the process of creating a screw thread. There are many methods of generating threads, including subtractive methods (many kinds of thread cutting and grinding, as detailed below); deformative or transformative methods (rolling and forming; molding and casting); additive methods (such as 3D printing); or combinations thereof.
Sohal welding works is manufacturing various types of machines to provide solution of making thread for construction work i.e for scaffolding industry. The processes are as follow:
Thread cutting, as compared to thread forming and rolling, is used when full thread depth is required, when the quantity is small, when the blank is not very accurate, when threading up to a shoulder is required, when threading a tapered thread, or when the material is brittle. Mainly this method is used to make thread in following applications TMT bars, Foundation bolts etc.
Linco machine is manufactured in Sohal Welding Works unit with high class of engineering design and workmanship with base structure made from Mildsteel, gearbox from cast iron fitted with taper roller bearings to bear pressure of threading during it's working and bed made from cast iron machined and hardened to ensure smooth working and accurate results.
Machine runs with pulley and belt drive by using electric motor of Cromphton or simens brand and die head is mounted to hold chasers with which one can vary the job diameters by using gauges provided with the machine.
Working: In this machine job is held in the jaws of vice which are hardened to ensure rigid grip of job with having different dimensions on each size to cope up with various sizes. Then job is moved forward towards the rotating die head and once threading is started job will move forward automatically until the moving slide stopper struck with die head opening handle.
Consumables: In this machine chasers, electric power and small amount of cutting oil is used as consumables.
Features: Low initial cost, easy to operate, Cuts and do threading in same setup, easy to change pitch of thread by changing chasers.
Thread forming and thread rolling are processes for forming, rather than cutting, screw threads, with the former referring to creating internal threads and the latter external threads. In both of these processes threads are formed into a blank by pressing a shaped tool, commonly called a 'thread rolling die' against the blank, in a process similar to knurling. These processes are used for large production runs because typical production rates are around one piece per second. Forming and rolling produce no swarf and less material is required because the blank size starts smaller than a blank required for cutting threads; there is typically a 15 to 20% material savings in the blank, by weight.
Materials are limited to ductile materials because the threads are cold formed. However, this increases the thread's yield strength, surface finish, hardness, wear resistance, and fatigue strength due to conformance of the grain with the thread profile. Also, materials with good deformation characteristics are necessary for rolling; these materials include softer (more ductile) metals and exclude brittle materials, such as cast iron. Tolerances are typically ±0.001 in. (±0.025 mm), but tolerances as tight as ±0.0006 in (±0.015 mm) are achievable. Surface finishes range from 6 to 32 micro-inches.
| Image | Description | Application |
|---|---|---|
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Flat dies (flat roller) | Machine, tapping and wood screws |
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Cylindrical in-feed 2 dies | Large or balanced screws, threaded bar stock |
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Cylindrical in-feed 3 dies | Tube fitting, spark plugs, threaded bar stock |
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Planetary dies (planetary roller) | High volumes screws, sheet metal screws, and drive screws |
Source
Threading_(manufacturing)
Two Roll Thread Rolling Machine: This machine is specially designed to meet the requirements of scaffolding industry as Tie Rod is used widely all over the world and many countries import it and SWW Brand always thinks to save the cost and most important time of their valuable clients so our engineering team made a special model for it.
Machine structure is fabricated from fresh Mild Steel sheets and welded with MIG welding machines to ensure high quality and strength to each and every part, then machining is done on planner machine to match the structure with designed structure. Gearbox body is also made from Mildsteel with machining done on boring machine, drilling and threading done on VMC machine. All gears are made with high precision machines to ensure smooth and accurate working of gearbox and gear oil of HP brand is used in machine for it's high performance.
Electrical work plays a vital role in every machine so it's done by electrical engineers and parts used are of Schinder brand that is very much popular all over the world. All wires used in wiring comes with indication of working of each part.
Hydraulic system is the heart of thread rolling machine and we use hydraulic system of Yuken brand, soneliod valves of Spac brand and motor of Cromphton.
Working: Two roll thread rolling machine is very easy to use one have to adjust the helix angle and use thread roll of correct pitch as per his requirement and then just put the raw material in between the thread rolls and press the foot pedal or do job clamping from the control panel and job with move forward automatically as per the pitch of the job.
Production: This machine gives production of 6 mtr tie rod in3 minutes only. One thread roll set able to give production of 20 tons approx depends on quality of raw material.
Three roll thread rolling machine: This machine is specially designed to meet the requirements of scaffolding industry as threading on pipe is very difficult process on two roll machine and our engineers had done a lot study and come up with three roll machine in which force is applied to the pipe from all three sides to ensure there is no any bend in the pipe after threading, moreover speed of threading is increased to meet the requirement of market.
In our this special model one can able to do threading on hollow jacks, solid jacks and prop sleeve by adjusting the helix angle and distance between thread rolls.
Machine structure is fabricated from fresh Mild Steel sheets and welded with MIG welding machines to ensure high quality and strength to each and every part, then machining is done on planner machine to match the structure with designed structure. Gearbox body is also made from Mildsteel with machining done on boring machine, drilling and threading done on VMC machine. All gears are made with high precision machines to ensure smooth and accurate working of gearbox and gear oil of HP brand is used in machine for it's high performance.
Electrical work plays a vital role in every machine so it's done by electrical engineers and parts used are of Schinder brand that is very much popular all over the world. All wires used in wiring comes with indication of working of each part.
Hydraulic system is the heart of thread rolling machine and we use hydraulic system of Yuken brand, soneliod valves of Spac brand and motor of Cromphton
Working: Machine is very easy to operate one have to put the raw material in machine and only pressing clamp button and job with automatically come out of the machine, depth of the thread can be easily adjusted from lock nut provided on the moving cylinder arm. Helix angle is changed as per the diameter of the job and thread roll set. One have to put manderl in pipe during threading of prop sleeve as per the wall thickness of pipe.
Production: This machine gives production of 1 pc of 750mm hollow and solid jack in 1 minute and approx 5000 pcs of jacks can be threaded with one thread roll set and it can be resharped again. For prop sleeve 2 pcs of prop sleeve can be threaded in 1 minute and approx 7500 pcs can threaded with one thread roll set.
Thread roll for two roller machine: In this machine mainly two products are manufactured first one thread bars and second one tie rods we are manufacturing both thread roll sets as per the requirement of client.
For thread bars thread rolls vary with the job diameter and pitch of thread
For tie rods there are two standards one is with round profile and second one with square profile.
Thread roll for three Roller Machine: In this machine jacks and props production is done and we have thread roll sets accordingly for the same and pitch and profile vary according to the client requirement.
Solid Jack Thread Roll Set: This thread roll set is used to thread solid rods used in scaffolding with having square and round profile as per cleint requirement.
Hollow Jack and Steel Prop Thread Roll Set: This thread roll set is used as a common thread roll set for hollow jacks and steel props one have to do adjustment in machine to do both jobs with same thread roll set. Profile and pitch of thread can be adjusted according to client requirement.
