Shift Fork Gear Box for Barmag Winder

Product Description

I.  Historical Development

The fundamental task of the yarn traverse mechanism in a winding head is to drive the yarn guide in precise reciprocating motion along the bobbin axis, ensuring that the yarn is laid uniformly and compactly onto the bobbin to form an acceptable package. The evolution of this mechanism is closely intertwined with the broader development history of Barmag high-speed winders.

1922–1960s（Early winder era）:

At the time of Barmag's founding in 1922, synthetic fiber spinning speeds were relatively low (200–800 m/min), and winding machines universally employed grooved-drum (cam) traverse mechanisms in which a closed helical groove machined on the surface of a rotating drum guided the yarn in reciprocating motion. While mechanically simple and reliable, this approach was limited by drum mass and inertia: at higher speeds, package edge formation deteriorated and groove wear accelerated sharply.

1969: A milestone in high-speed winding — the birotor traverse fork mechanism

Barmag developed the world's first high-speed winder in 1969, which represented a decisive technological breakthrough. To accommodate the substantially higher winding speeds, Barmag developed and commercialized the birotor rotary-blade traverse mechanism, the heart of which is a precision traverse fork gearbox: two rotors rotating in opposite directions each drive a rotary blade (wing) that alternately assumes responsibility for guiding the yarn, thereby achieving high-speed reversal without mechanical inertia.

In this mechanism, two counter-rotating rotors drive the rotary blades such that the yarn is alternately guided along the edge of the main guide plate and the edge of the auxiliary guide plate; after guiding the yarn in one direction, one blade descends below the guide plate while the other blade takes over guidance in the reverse direction.

1980s(Precision winding introduces new gearbox requirements):

Barmag laid the foundation in the 1980s for a completely new method of depositing yarn on packages, substantially increasing productivity. This period introduced the new requirement for precision transmission ratio control: the ratio between the yarn guide reciprocation frequency and the bobbin rotational speed (the winding ratio) had to be continuously and finely adjusted to achieve active ribbon breaking, ensuring uniform package density throughout the winding cycle.

Late 1980s–2000s(The SW→CW→ACW winder progression):

As POY/FDY spinning speeds advanced from 2,500 m/min to beyond 5,000 m/min, Barmag's winder series evolved progressively through SW (Spindle Winder) → CW (Craft Winder) → ACW (Automatic Craft Winder) generations. The CW6 winder was equipped with the Bio Rotor birotor traverse mechanism; with each generation, the precision and lubrication requirements of the traverse fork gearbox advanced correspondingly.

2007–present(The SW→CW→ACW winder progression):

As Barmag SW, CW, and ACW series winding equipment has become increasingly prevalent in China, a number of local enterprises specializing in spare parts maintenance, repair, and replacement services have emerged. Among these, Jiaxing Shengbang Mechanical Equipment Co., Ltd. was one of the earliest companies in China to develop localized maintenance and repair expertise for Barmag equipment. In response to the demanding requirements of Chinese manufacturers — high-speed production and minimal downtime — the company has refined the transmission precision and synchronization mechanisms of Barmag traverse gearboxes. The traverse gearboxes it produces are distinguished by their exceptional precision and extended service life, and have earned consistent acclaim from China's leading chemical fiber enterprises, including Tongkun Group, Xinfengming Group, Hengli Group, and Shenghong Co., Ltd.

The company is equipped with an extensive array of advanced production, inspection, and maintenance facilities, including CNC machining centers, original Schenck dynamic balancing machines from Germany, plasma spraying equipment from the 625th Institute of the Ministry of Aerospace Industry, and original Barmag hot roller temperature calibrators from Germany, among others. Its independently developed bicomponent spinning test machine represents the culmination of years of accumulated expertise and advanced system integration capabilities. This machine enables the rapid production of monocomponent, bicomponent, and multicomponent fibers, as well as POY, FDY, medium-tenacity yarns, and fine-denier industrial yarns — all on a single platform. The machine has received multiple patent certifications and has been highly praised by customers in Germany, Japan, and other countries.

II. Design Characteristics and Construction

The Barmag traverse fork gearbox is a compound mechanical system integrating three core functions: precision power transmission, high-speed reversal, and accurate synchronization. Its principal constituent elements are as follows:

① Birotor rotary-blade drive assembly Two counter-rotating rotors each carry a rigidly attached rotary blade (traverse fork / wing). The two blades alternately assume yarn guidance within the traversing plane: after completing guidance in one direction, one blade descends below the guide plate while the other takes over from above, achieving continuous, uninhibited directional reversal. The winding speeds attainable with birotor rotary-blade traverse systems substantially exceed those of reversing-shaft traverse systems, making this configuration the standard choice for high-speed POY/FDY winding.

② Precision reduction and transmission gear train A high-speed motor drives the two rotors via precision helical or bevel gears. The gear transmission ratio determines the yarn guide reciprocation frequency and thereby the winding ratio. Gear precision grade requirements are ISO 5–6 (equivalent to DIN 5–6) to ensure smooth, low-noise transmission. The phase relationship between the two rotors is rigidly locked by the gear mesh geometry, guaranteeing precise timing of the handover between blades.

③ Main/auxiliary guide plate system The main guide plate (fixed) provides the guiding edges at the reversal points of the traverse stroke. The auxiliary guide plate is capable of transverse micromotion to adjust the actual reversal position, supporting the traverse stroke shift function employed in precision winding. The yarn contact edges on the guide plates are typically provided with hardened carbide or ceramic inserts to maximize wear life.

④ Y-shaped traverse fork yarn guide The Y-shaped fork (also termed push-rod fork or yarn guide fork) is manufactured from high-strength alloy or specialized composite material to ensure wear resistance and dimensional stability under high-speed operating conditions. Its principal function is to guide the yarn precisely into the winding position and, in cooperation with the traverse drive (cam or groove drum), to control yarn distribution during reciprocating motion so that the yarn is wound uniformly onto the bobbin.

⑤ Winding ratio control and ribbon-breaking system Variable-frequency drives continuously fine-tune rotor speed (i.e., traverse frequency) in real time, periodically shifting the winding ratio during precision winding to cause the yarn deposition trajectory to drift continuously, preventing repeated superposition at any single angular position (ribbon formation). The Barmag Guide control system monitors and regulates the winding ratio throughout the entire winding cycle.

⑥ Lubrication and sealing system The gearbox interior employs grease lubrication or circulating oil lubrication to protect the gear flanks at high speeds. Precision lip seals at the shaft penetrations prevent lubricant migration towards the yarn path.

III.Evolution of Associated Components

Blade/fork material evolution:

• First generation: tool steel, surface hardened
• Second generation: high-speed steel (HSS) or tungsten carbide (WC-Co) blade tips
• Third generation (current): silicon nitride (Si₃N₄) or alumina ceramic composite blade tips; yarn contact surfaces finished to mirror grade (Ra ≤05 µm), substantially extending service life and minimizing yarn damage

Gearbox sealing material evolution:

• Early period: felt ring seals
• Intermediate period: rubber lip seals
• Current: PTFE lip seals, resistant to high peripheral speeds and finish oil contamination

‌IV. Primary Component Materials‌

The principal components of the traverse fork gearbox include:

• ‌Transmission Gears:‌Driving Gear and Driven Gear.
• ‌Rotor Shaft‌
• ‌Gearbox Housing‌
• ‌Rotor Bearings:‌The most critical lifespan-determining component.
• ‌Y-Shaped Rotary Blade / Traverse Fork Wing‌
• ‌Sealing Elements‌
• ‌Lubricating Grease

V. Principal Classifications and Model Designations

Classification by traverse operating principle:

Type A — Birotor rotary-blade traverse mechanism The mainstream high-speed traverse mechanism for Barmag winders, applicable to POY/FDY/HOY processes, supporting winding speeds up to 6,500 m/min.

Type B — Reversing-shaft traverse mechanism The WinFors winder relies on the reversing shaft as its traverse system, delivering exceptionally gentle yarn treatment. Although the speeds achievable are lower than those of birotor systems, winding speeds of 2,500 to 4,000 m/min are attainable; furthermore, the winder can be converted from a 4-end to an 8-end configuration simply by exchanging the traverse system.

Type C — Groove-roll traverse mechanism Applied in industrial yarn (IDY) winding. Jiaxing Shengbang Mechanical Equipment Co., Ltd. is the only supplier in China can provide technology update services for Barmag winding system.

 VI. Installation Requirement & steps

The quality of gearbox installation directly governs its operational service life. The following preconditions must be met before installation commences.

1. Environmental and tooling requirements

• The installation area must be clean and dry, free from airborne fiber contamination (work under temporary protective screens if necessary)
• Ambient temperature: 15–30°C (avoid low-temperature assembly, which causes thermal expansion during subsequent operation to alter fits beyond design intent)
• Required tools:

• High-accuracy torque wrench
• Bearing induction heater
• Dial indicator
• Lint-free cloths and IPA or industrial solvent
• Non-ferrous (copper or nylon-faced) mallet for light corrective tapping
• Bearing installation sleeve matched to shaft journal diameter (contacts inner race only)

2. Pre-installation dimensional inspection (mandatory)

3. Fastener torque requirements

All threaded connections（like Housing joint face bolts, Winding head mounting flange bolts, and Shaft locking nut） must be secured with medium-strength thread-locking compound. Flange faces must be clean and free of oil contamination.

4. Alignment precision requirements

Use a laser alignment tool to precise shaft alignment; visual estimation alone is not acceptable.

5. installation steps

The following procedure applies to a complete gearbox swap (unit replacement). Partial component replacement (blades, seals) is addressed in the maintenance section below.

Step 1: Machine shutdown and safety lockout

Shut down the winding machine following the standard shutdown procedure; confirm that both the spindle motor and traverse motor are de-energized

Step 2: Removal of the old gearbox

1. Disconnect the coupling (or belt drive) between the motor and the gearbox
2. Disconnect all electrical, pneumatic, and lubrication connections; protect open ports with clean plugs
3. Support the outgoing gearbox with a chain hoist or pneumatic lifting device; remove all mounting flange fasteners
4. Withdraw the gearbox horizontally and steadily (do not allow the gearbox weight to bear on the exposed shaft journal or blade assembly); set down safely

Step 3: Mounting face cleaning and inspection

1. Using a lint-free cloth and industrial solvent, thoroughly clean the winding head mounting flange face, dowel pin holes, and drive shaft end face
2. Using a scratch-free oilstone or fine abrasive paper, remove any rust or burrs from the mounting face; re-measure mounting face flatness with a dial indicator
3. Inspect the condition of all dowel pins; replace any that are damaged

Step 4: New gearbox pre-installation inspection

On receipt, inspect the gearbox exterior for transport damage

Step 5: Gearbox installation

1. Apply a thin, uniform bead of liquid anaerobic sealantto the mounting flange face, keeping clear of threaded holes and dowel pin holes
2. Engage the locating dowel pins to correctly position the gearbox flange
3. Install all flange fasteners in three passes using the cross-tightening (diagonal) sequence
4. Reconnect the drive coupling or belt; complete precise shaft alignment verification using a laser alignment tool

Step 6: Blade installation and phase verification

1. Insert each rotary blade into the rotor head slot in the correct rotational direction (CW/CCW) and tighten the retaining screw to the specified torque
2. Measure blade tip runout with a dial indicator
3. Slowly rotate both rotors by hand; confirm that the phase difference between the two blades in the traversing plane conforms to the design specification, and verify that neither blade risks colliding with the other at the reversal points
4. Install and adjust the main and auxiliary guide plates; confirm that the clearance between the guiding edges and the blade travel path conforms to the specified value

Step 7: Grease filling

1. Confirm that the gearbox has been pre-filled with the specified grease quantity at the factory (verify before first use)
2. For a dry (unfilled) gearbox, use a grease gun to inject the specified quantity of grease slowly through the lubrication fitting. Do not overfill— over-greasing is one of the most common causes of bearing overheating

Step 8: Trial run and verification

Once normal operation is confirmed, return to full production

 
FAQ

I. What Shengbang do in this area？

We possess a first-class engineering and technical team, combined with advanced and complete production and testing equipment, has laid a solid foundation for us to provide high-quality and first-class services to chemical fiber enterprises. Adhering to the core tenet of independent innovation, the company is committed to providing long-term, stable and comprehensive technical services for major chemical fiber enterprises, helping the industry achieve high-quality development.

II. About Shengbang's competitiveness?

Our company is equipped with advanced and comprehensive equipment for the production, inspection, testing and maintenance of chemical fiber machinery, including multi-functional CNC machine tools, original balance correction equipment from Schenck Process GmbH (Germany), plasma spraying equipment from the 625th Institute of the Ministry of Aerospace, and original godet thermal calibration instruments from Barmag AG (Germany).

Relying on years of rich experience accumulated in the field of chemical fiber production and mature system integration technology, we have successfully developed a revolutionary prototype multi-purpose spinning machine, with the help of which flexible production switching between single-component, dual-component, multi-component, Pre-oriented Yarn (POY), Fully Drawn Yarn (FDY), medium-strength yarn, ultra-fine yarn and industrial yarn can be easily achieved.

Note: This article is compiled from Oerlikon Barmag publicly available technical literature, industry journals, and patent documents. Specific part numbers for traverse fork gearboxes constitute proprietary spare-parts catalogue information; detailed specifications and current model designations should be sought directly from the Oerlikon Barmag customer service organization.