Heavy Duty Horizontal Curve Rail for Overhead Conveyor

Hangzhou Ocean Industry Co., Ltd. is one of the most experienced manufacturers and suppliers of Heavy Duty Horizontal Curve Rail for Overhead Conveyor in China. Welcome to wholesale customized Heavy Duty Horizontal Curve Rail for Overhead Conveyor at competitive price from our factory. Good service and quality products are available.

 

The heavy-duty horizontal curve rail is the cold-formed manganese steel C-track that turns an enclosed-track overhead conveyor through 30°, 45°, 60°, 90°, 135° and 180° horizontal bends. It is supplied as a nitrided, ready-to-bolt arc for QXG250 and QXG300 chain, formed to one fixed radius so that both the chain path and the pendant path are fixed on the day the rail is installed.

Of all the components on a conveyor system, the curve rail is the one that does not move. Chain, wheels, bearings, drive units and hanger brackets are consumables with defined replacement intervals; a curve rail is bolted into position once, and its geometry then governs every wheel passage, every loaded pendant swing and every thermal cycle for the life of the line. Its performance is therefore decided in the factory rather than on site – by the accuracy of the arc, by the concentricity of the flange joints and by the condition of the inner flange where the wheel actually runs.

Standard angle segments are cut from the same profile, and are cut to any degree to suit site conditions. Non-standard radii, shortened or extended tangents, special drilling patterns and split arcs for difficult site access are produced to drawing.

The curve rail is matched to the chain it carries, so selection starts with the chain series rather than with the radius:

• QXG150 or QXG200 line → standard-duty curve rail, 57 × 67 × 3 mm wall, R600 / R800.

• QXG250 or QXG300 line → heavy-duty curve rail, 65 × 72 × 5 mm wall, R1000 / R1200.

• Chain series unknown → measure the track cross-section or photograph the rail, the chain and the drive unit. We will identify the matching curve rail before quoting, so the order is placed against the correct wall thickness and radius.

The two tables below answer two different questions. The first lists the curve segments available per model, with radius R in millimetres and available curve angle n in degrees. The second gives the full dimensional, material, tolerance and weight data for the heavy-duty rail for QXG250 and QXG300 chain, so a buyer or an installation contractor can check the rail against the line drawing before ordering. The tables carry the controlling specification; the text on this page explains how those values behave on a running line.

Curve segment availability by model. R = curve radius in mm; n = available curve angle in degrees. Angles outside this list are cut to order from the same profile.

Type	R	n
QXT-150	500,600	30,45,90,180
QXT-200 206	600,800	30,45,90,180
QXT-240 250	800,1000	30,45,90,180
QXT-300	800,1000	30,45,90,180

The values below apply to the heavy-duty curve rail for QXG250 and QXG300 enclosed-track chain. Where the two columns differ, the difference is set by the chain's minimum articulation radius rather than by the rail profile.

Parameter	QXG250 Heavy-Duty	QXG300 Heavy-Duty
Rail material	16Mn (Q345B) manganese steel	16Mn (Q345B) manganese steel
Cross-section (W × H × wall)	65 × 72 × 5 mm	65 × 72 × 5 mm
Profile type	C-type enclosed track	C-type enclosed track
Surface treatment	Gas nitriding HRC 25–30	Gas nitriding HRC 25–30
Nitriding depth	0.3–0.5 mm diffusion layer	0.3–0.5 mm diffusion layer
Core hardness	HB 140–180 (untreated)	HB 140–180 (untreated)
Yield strength	≥345 MPa	≥345 MPa
Tensile strength	≥510 MPa	≥510 MPa
Standard curve radii	R1000 / R1200 mm	R1000 / R1200 mm
Minimum curve radius	R800 mm (reduced speed)	R1000 mm (reduced speed)
Available angles	30° / 45° / 60° / 90° / 135° / 180°	30° / 45° / 60° / 90° / 135° / 180°
Custom angles	Any angle, cut to specification	Any angle, cut to specification
Radius tolerance	±0.5 mm (full arc)	±0.5 mm (full arc)
Entry/exit tangent length	100 mm min (straight lead-in)	100 mm min (straight lead-in)
Flange joint type	Bolted flange, 4 × M8 bolts	Bolted flange, 4 × M8 bolts
Alignment dowel pins	2 × Φ8 mm (H7/h6 fit)	2 × Φ8 mm (H7/h6 fit)
Joint concentricity tolerance	≤0.1 mm	≤0.1 mm
Max operating temperature	260°C (nitrided)	260°C (nitrided)
Thermal expansion coefficient	12 × 10⁻⁶ / °C (16Mn)	12 × 10⁻⁶ / °C (16Mn)
Expansion joint gap (oven zone)	15–20 mm at entry/exit	15–20 mm at entry/exit
Weight per 90° curve (R1000)	approx. 12.5 kg	approx. 12.5 kg
Weight per 180° curve (R1000)	approx. 25 kg	approx. 25 kg
Surface finish (inner flange)	Ra 3.2 μm (cold-formed)	Ra 3.2 μm (cold-formed)

A tolerance matters only when it changes what happens during installation or operation. These four values are the ones buyers query most often, and each has a direct consequence on site.

• Radius tolerance, full arc – the arc arrives as one continuous curve at the radius on the drawing. Support brackets can be set out against the same template radius and bolted up without shimming, pulling or re-bending the rail into alignment on site.

• Joint concentricity at the dowel-pinned flange – the wheel crosses from one segment to the next without meeting a step. No transition piece is needed between the curve and the straight rail, and no impact is generated at the joint that would work loose the flange bolts.

• Entry and exit tangent – the straight rail runs into the curve along a true tangent rather than meeting it at a kink. This is the detail that keeps tread wear even across the running band and removes the sharp edge a wheel would otherwise strike at the curve mouth.

• Inner flange surface finish from cold forming – this is the surface the wheel actually contacts. It is left smooth enough for the tread to bed in and polish its own contact band, instead of scuffing along a single edge line.

Where a layout cannot meet the geometry above – a curve that has to be joined inside a transfer station, for example, or one that must start immediately at a drive unit – send the layout and we will advise where the joint and the tangent can be placed so that no hard entry is introduced.

The base material is 16Mn (Q345B) manganese steel, cold-formed into the C-profile used by enclosed-track chain. Manganese gives the profile two properties at once: enough toughness for the 5 mm wall to carry the cyclic lateral load of loaded pendants without the flange leaning or deforming, and enough ductility to be formed into a smooth continuous arc rather than a series of flats. Mild steel and through-hardened steels cannot deliver both at the same wall thickness, which is why they are not substituted in this application.

Surface treatment is chosen from three options, and the choice is driven by what the route passes through rather than by price:

• Gas nitrided, standard supply – a HRC 25–30 case over a diffusion layer. The case is deliberately kept softer than the wheel tread, so the rail wears in against the wheel instead of fighting it: the running surface polishes to a matching contact band, and wear is distributed along that band rather than concentrated on one edge. This is the correct specification for dry lines – powder coating, paint ovens, general assembly – where the rail sees wheel traffic rather than moisture.

• Galvanized – specified where the route passes through wet processes, e-coating, wash or cooling tunnels, or where the line runs outdoors. The corrosion barrier sits on the outside of the profile; the running surface is still expected to bed in against the wheel.

• E-coated, black epoxy – specified for chemical exposure, including degreasing, pretreatment and paint-mist atmospheres, where both the outside of the profile and the flange faces need a continuous coating rather than a bare or nitrided surface.

Oven zones are treated as a separate case. For a curve inside or within reach of an oven running above roughly 120°C continuously, specify the nitrided rail together with an expansion joint at the oven-side flange, and galvanized support brackets. The rail grows with temperature, and the joint gap is the allowance that lets it do so without bowing sideways or opening the C-profile at the flange.

The heavy-duty curve rail is specified for pendant loads of 30–100 kg per pendant at chain speeds of 5–15 m/min through 90° or 180° horizontal turns. Inside that envelope, radius is the variable that protects wheel bearings and chain articulation. A tighter radius turns the chain more sharply, so each wheel pushes harder against the inner flange and less of the load envelope is left for speed and pendant weight.

Two of the limits are set by the chain rather than by the rail: QXG250 chain articulates down to R800 and QXG300 to R1000. Below those radii the chain, not the curve rail, becomes the constraint, which is why a smaller radius is only offered with a corresponding reduction in speed or payload. The table below gives the radius we would specify for the common cases.

Application	Recommended Radius
90° standard turn, speed ≤10 m/min	R1000 mm
90° standard turn, speed 10–15 m/min	R1200 mm (reduces centrifugal force 17%)
180° return bend, any speed	R1200 mm (minimizes chain articulation stress)
Space-constrained, speed ≤8 m/min	R800 mm (QXG250 only, reduced payload)

If your layout forces a radius below the recommended value, send the radius, the pendant weight and the line speed together rather than the radius on its own. The rail can be produced to almost any radius; what has to be checked is the combined behaviour of chain, wheel and rail at that radius, and that check is what decides whether the turn is workable or whether the two straights either side of it need to be repositioned.

All angles are cut from the same profile, so a 45° curve and a 135° curve are produced on the same forming tooling and share the same flange and dowel geometry. That matters for layout work: a change of angle along a route does not require a change of rail type or bracket type, so one line can drop through 30°, run a long 90° bend, return through 180° and still use a single curve rail family.

Curves outside the standard list are produced to specification: any angle cut to drawing, non-standard radius, shortened or extended tangent, a drilling pattern matched to an existing bracket, and arcs split into shippable or liftable segments. To price these, send the angle, the radius, the quantity and the position the curve occupies in the layout. A PDF drawing, or a photograph of the existing rail with the key dimensions marked on it, is usually enough.

Replacement arcs for existing systems are quoted the same way. Where the original radius and bolt pattern can be measured or drawn, the new rail can be produced to drop into the brackets already on the structure, which converts a shutdown into a rail change rather than a layout change.

A curve rail is bought as part of a system – chain, straight rail, brackets, hangers and drive – so compatibility is worth confirming before the quotation rather than after delivery.

• Chain – the heavy-duty rail is produced for QXG250 and QXG300 enclosed-track chain. State the chain series on the enquiry; if it is not known, the track cross-section identifies it.

• Straight rail – curve and straight segments share the same C-profile, the same flange face and the same dowel pattern, so no adapter or transition piece is required at the joint. Segments from different production batches also bolt together, because the flange and dowel dimensions are the same across the family.

• Wall thickness – the outer dimensions of the standard-duty 3 mm profile and the heavy-duty 5 mm profile are identical, which means a standard-duty curve will physically fit a QXG250 line and the chain will run in it. It will not carry the load. The 3 mm wall is rated for light pendants only, and a heavy line will deform the flange well before the wheels or the chain are worn. Match wall thickness to chain series, and do not mix wall thicknesses around one loop: the change in stiffness at the transitions produces inconsistent wheel contact, which shows up as noise and uneven wheel wear.

• Support and hanger brackets – quoted separately from the curve, because the number and spacing depend on the arc length, the pendant load and the distance to the nearest structural steel. They are usually supplied with the curve so that the whole turn is installed in one operation.

• Expansion joints – required at the oven-side flange joints of any curve that runs hot or sits close to an oven face. They are ordered with the curve, since the joint is a machined feature of the flange rather than an accessory fitted later.

On a coating line the horizontal curve usually carries the hardest combination of conditions on the whole track: the heaviest pendant load, a change of direction, and – on most layouts – the oven boundary. These are the positions where curve rail specification decides line performance.

• Oven entry and exit arcs – the curve that leads the chain into the curing oven sits between ambient air and the oven face. It sees the temperature range of the process and the pendant load at the same time, and it is the position that takes the expansion joint.

• Return bends at the end of the loop – the 180° arc reverses the chain where accumulated chain tension is highest, and is the position where the largest radius is normally specified.

• Load and unload arcs – where operators attach and remove the heaviest pendants, often at the slowest line speed and with the greatest load swing on the hook.

• Dip, wash and pretreatment curves – wet sections, where galvanized or e-coated curves and galvanized brackets are specified so that the track does not become the corrosion point of the line.

• Buffer and accumulation arcs ahead of the oven – where line speed and pendant spacing vary, so the spacing of wheels around the arc changes and the load is distributed unevenly along the curve.

The same rail family is used outside coating plants, on overhead assembly lines carrying heavy components and wherever an enclosed-track chain has to change direction under load. What the curve rail has to resist is the same in every case: a repeated lateral load applied through a small contact area, for the whole working life of the line.

A curve is installed in the same sequence as the straight rail it joins: brackets first, set out against the template radius, then the arc lifted into position and bolted through the flange, with the dowel pins locating the joint.

• Set out the support brackets around the arc before the rail is lifted. Brackets carry the lateral load of loaded pendants into the building structure along the whole turn; if they are placed only at the ends, the two end brackets take the load of the entire curve and the profile begins to lean.

• Fit the dowel pins before final bolt tightening. The pins locate the joint at the designed concentricity; the bolts hold it closed but they do not align it.

• Do not trim the tangent ends on site to make a curve fit. The straight lead-in is formed into the segment, and cutting it back removes the transition the wheel enters on and reinstates the kink the rail was made to avoid.

• Set the oven-side joint clearance as a gap. That clearance is the allowance for thermal growth; closing it up during installation removes the margin the rail needs when the oven comes up to temperature.

• Draw the chain through the new curve by hand or at crawl speed with the line unloaded, and watch the wheel pass each joint, before the line is run at production speed. On a heavy line, catching a mis-set joint at this stage costs minutes; catching it after commissioning costs a shutdown.

Because the curve rail is fixed for the life of the line, the arc is verified before the rail is released rather than accepted as formed. Four controls in production protect the dimensions that the installation depends on.

• Radius is measured around the arc against a full-scale template, at short intervals in place of end-to-end spot checks, so a deviation in the middle of a long bend cannot pass unnoticed between the entry and exit tangents.

• Post-forming stress relief at 550°C reduces the residual stress left in the profile by cold forming and keeps inner flange flatness deviation within 0.3 mm. Flatness is a wear control rather than a cosmetic one: an inner flange that is not flat loads the wheel on one edge of its tread, and edge loading is what makes wheel treads spall instead of wearing evenly.

• Closed-loop radius feedback during forming holds the radius steady along the length of the curve, so a 180° bend measures the same at both ends as it does at the centre.

• Flange faces and dowel holes are produced so that the joint dimension belongs to the two segments that will be bolted together on site, and case depth is controlled as well as surface hardness – the nitrided case is dimensioned for the wheel traffic a multi-shift line produces, over 50 000 wheel passages per year, without forming a step at the running band.

Records can be supplied with the order. State the requirement when you enquire – material specification, radius and flange readings, nitriding depth data – so the records are raised with the production batch instead of being reconstructed after the rail has shipped.

Curve rails are heavy, awkward shapes that distort if they are stacked or dropped, so the handling decisions are best taken when the order is placed rather than when the container is being loaded.

• Destination and mode – tell us the port or the delivery address and whether the curves travel by sea or by air. Air freight is normally used only for a sample or a single replacement segment.

• Handling at the receiving end – state whether a forklift or an overhead crane is available, and whether the arc has to pass through a standard door or a goods lift. This decides whether a large return bend is supplied as one arc or split into sections.

• Storage on site – tell us how long the curves will stand before installation. A set that is installed on arrival needs less corrosion protection than a set that will be stored outdoors for months before a shutdown.

• Access into the building – a 180° arc is a large item to manoeuvre inside a working plant. Splitting it at a flange joint is usually less disruptive than removing a wall or opening the roof, and the joint is designed to be re-joined on site without loss of concentricity.

Each of these choices affects packing and price, and all of them are simpler to arrange before the profile is formed than after the curves are standing in the yard.

A quotation that can be checked against the line drawing, rather than a price that has to be corrected later, needs six inputs:

1. Chain series, or the track cross-section where the series is not known.

2. Radius and angle of every curve on the layout, with the quantity required for each combination.

3. Pendant load per hook and the chain speed the line runs at.

4. Route environment – whether an oven or a wet process lies close to the curve, and whether the line is indoors or outdoors.

5. Surface treatment required for each curve: nitrided, galvanized or e-coated.

6. Destination port or delivery address, and the date the rail has to be on site.

Where a layout drawing exists, mark the curves on it and send it with the enquiry. Where no drawing exists, send the building column grid together with the positions of the load and unload stations and the oven face; our engineering team will propose a radius and an angle for each turn around those fixed points before an order is placed.

If the requirement is a trial curve for an existing line rather than a set for a new installation, say so when you enquire, so that the quotation is written for the right quantity and the right packing.

Most curve rail complaints trace back to how the curve was specified or installed rather than to the rail itself. These are the recurring ones, with the symptom that identifies each.

1. A standard-duty curve used on a heavy line. Symptom: the chain sits low in the curve and wheels begin to ride the flange. Cause: the lighter wall cannot carry the pendant load, and it deforms before the wheels or chain are worn.

2. Wall thicknesses mixed around one loop. Symptom: noise and uneven wheel wear concentrated near the transitions. Cause: the change in stiffness between segments makes the wheel contact geometry inconsistent from one segment to the next.

3. An oven-adjacent curve installed with no expansion allowance. Symptom: the rail bows sideways close to the oven and the C-profile opens at the flange. Cause: thermal growth has nowhere to go, so it moves the rail instead of the joint.

4. Support brackets spaced too widely around the arc. Symptom: the flange leans, usually starting at the brackets nearest the entry. Cause: the lateral load concentrates at the two stiffest points instead of being shared along the turn.

5. The tangent cut on site to make the curve fit. Symptom: impact noise at the curve mouth and tread spalling that starts at the entry. Cause: the wheel meets a step instead of a tangent.

6. A curve ordered to a nominal radius that does not match the layout. Symptom: the arc has to be pushed, pulled or shimmed into position during installation. Cause: correcting a mismatch by force loads the flange in a direction it was not designed to resist.

Every one of these is cheaper to avoid at specification stage than to correct on a running line. If you are replacing a curve that shows one of these symptoms, send a photograph of the failed rail with the chain series and the radius; the failure pattern usually identifies the cause, and the cause decides whether a straight replacement rail will hold or whether the layout detail itself has to change.

 

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