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Product Description
The two-cavity PVC pipe production line by Chenxing Machinery is purpose-built for manufacturers who need to double small-diameter PVC pipe output without doubling floor space, labor, or energy consumption. Based on Western European extrusion technology, the line centers on the SJSZ 65/132 conical twin-screw extruder — alternatively available as the SJZ 51/105 — paired with a two-cavity die head that extrudes two pipes simultaneously at line speeds up to 2 × 10 m/min. The defining innovation is the four-tube single-control stainless steel spray calibration system: each of the two pipes passes through two independently controlled calibration stages, meaning adjusting one tube's parameters never disrupts the other. This eliminates the chronic waste problem of traditional multi-cavity lines where a calibration adjustment on one strand cascades into dimensional drift on the parallel strand.
For manufacturers producing PVC plumbing pipes, electrical conduits, and drainage pipes in the 16–63 mm range — the highest-volume segment in construction supply — this line delivers 120–250 kg/hr output at extruder power draws of just 18.5–37 kW. The energy-per-kg advantage over running two separate single-cavity lines is approximately 30–35%, because one extruder motor, one PLC, one vacuum pump, and one cooling circuit serve both cavities instead of duplicating every subsystem. The result: land cost halved, operator count halved, maintenance burden halved. For more on Chenxing's approach to efficient extrusion technology, see our full equipment range.
| Parameter | SJZ 51/105 Configuration | SJZ 65/132 Configuration |
|---|
| Extruder Model | SJZ 51/105 | SJSZ 65/132 |
| Pipe Diameter Range | 16–40 mm | 16–63 mm |
| Extruder Power | 18.5 kW | 37 kW |
| Extrusion Capacity | 120 kg/hr | 250 kg/hr |
| Max. Production Speed | 2 × 8 m/min | 2 × 10 m/min |
| Cavity Count | 2 | 2 |
| Calibration Type | Four-tube independent spray | Four-tube independent spray |
| Haul-Off | Auto single-control four-drawing | Auto single-control four-drawing |
| Cutting | Synchronized dual-cutter | Synchronized dual-cutter |
This is the technology that separates this line from conventional multi-cavity offerings. Each of the two extruded pipes passes through two independently controlled stainless steel spray calibration stages (four tubes total). Each calibration tube has its own vacuum level knob, water flow valve, and temperature readout on the control panel. When a finished-pipe OD measurement on one strand shows a deviation, the operator adjusts only that strand's calibration tube — the neighboring strand continues unaffected. On a conventional shared-manifold calibration system, adjusting vacuum or water flow on one tube changes pressure in the common header, shifting the other tube's calibration by 0.05–0.15 mm — enough to produce out-of-spec pipe. Independent control eliminates this entirely. The stainless steel construction resists corrosion from the slightly acidic water that results from HCl traces in PVC processing, a detail that matters when your calibration sleeves need to hold ±0.05 mm tolerance over years of continuous operation.
The SJSZ 65/132 (and SJZ 51/105) conical twin-screw extruder is selected specifically because its counter-rotating intermeshing geometry delivers high melt pressure stability — a non-negotiable requirement when one extruder feeds two die cavities. Melt pressure fluctuation at the die entry must stay within ±0.5 MPa; if one cavity momentarily draws more melt due to a micro-fluctuation, the parallel cavity sees a pressure drop and its wall thickness drifts. The conical screw's progressively decreasing channel depth acts as a natural pressure damper, delivering melt to the flow distributor at 22–28 MPa with variance under 0.3 MPa. Screws are 38CrMoAlA nitrided steel (HV ≥ 900) with bimetallic barrels, built for 15,000+ hours between rebuilds when processing standard UPVC dry blend with up to 10 phr CaCO₃ filler. The four-zone barrel heating (160°C → 170°C → 178°C → 185°C) uses PID-controlled ceramic band heaters with ±1°C precision, tied to the same PLC that governs both haul-off units.
Between the extruder die head and the two calibration inlets sits a precision flow distributor machined from chrome-plated tool steel. The distributor splits the single melt stream into two equal-flow channels with trim adjustment screws on each branch. During commissioning, a quick weight-per-meter test on both pipes identifies any imbalance; a quarter-turn on the trim screw redistributes melt within 30 seconds. Once set for a given die diameter, the distributor maintains ±1.5% flow balance over continuous runs. This is the mechanical insurance that both pipes hitting the calibration tank have identical wall thickness before sizing begins — calibration cannot fix what the die did not deliver evenly.
Each pipe strand has its own caterpillar haul-off unit, but all four belts are driven from a common motor through individual electromagnetic clutches. This means the line speed is unified — both pipes exit at exactly the same linear velocity — but each strand's belt tension is independently adjustable. If one pipe has a slightly thicker wall (legacy from a die insert that is 0.02 mm larger after 2,000 hours of wear), that strand's clutch can be micro-slipped to compensate without affecting the parallel strand. The polyurethane contact pads apply 50–300 N clamping force with pneumatic regulation, and the belts are quick-release for diameter changeovers in under 15 minutes per strand. For upstream material handling, Chenxing's mixing units provide the dry blend consistency this precision haul-off demands.
Each pipe strand is cut by a dedicated flying cutter synchronized to its haul-off speed via encoder feedback. The blade carriage tracks the pipe, cuts during motion (no stopping the line), and returns — all while the parallel cutter operates on its own timing for its strand. Cut lengths are independently programmable from 0.5 m to 6 m per strand via the HMI, with ±1.5 mm repeatability. An automatic stacker collects finished pipes from both strands onto a common rack, sorted by length if the two strands are running different cut-length programs. For manufacturers running both 3 m and 4 m pipe orders on the same shift, this dual-program capability effectively turns one line into two SKU-producing lines without a changeover pause.
Dry Blend Feeding — UPVC compound (resin + stabilizer + CaCO₃ + processing aids) is loaded into the extruder hopper via vacuum auto-loader. A gravimetric feeder maintains ±0.5% blend consistency.
Twin-Screw Plasticizing — Material transits four temperature zones (160°C–185°C) through the conical twin-screw, reaching full gelation at 65–75% fusion degree before entering the flow distributor.
Two-Cavity Die Forming — The melt stream splits evenly in the chrome-plated distributor, feeding two identical die heads that form two pipe parisons simultaneously at identical melt temperature and pressure.
Independent Four-Tube Calibration — Each parison enters its own pair of stainless steel spray calibration tubes. Vacuum (–0.02 to –0.04 MPa) draws the hot PVC against water-lubricated brass sizing sleeves. Each tube's vacuum and water flow is independently set and monitored.
Spray Cooling & Dual Haul-Off — Secondary water spray tanks cool both pipes to ≤35°C surface temperature. Each strand is pulled by its own caterpillar belt unit with independent clamping tension, all driven from a common synchronized motor.
Dual Cutting & Stacking — Each strand's flying cutter trims to its programmed length. The automatic stacker collects finished pipes from both strands and organizes them for bundling and QC inspection. For product packaging solutions, visit our products page.
| Pipe Type | Typical Diameter | Wall Thickness Standard | End-Use Market |
|---|
| Electrical Conduit | 16–32 mm | IEC 61386, UL 651 | Residential, commercial, industrial wiring |
| Building Drainage (DWV) | 32–63 mm | ISO 3633, ASTM D2665 | Residential and commercial plumbing |
| Cold Water Supply | 20–63 mm | ISO 1452, ASTM D1785 | Building water distribution |
| Agricultural Irrigation | 16–50 mm | ISO 16422 | Drip and sprinkler systems, greenhouses |
| Cable Protection / Telecom Duct | 25–63 mm | IEC 61386-24 | Underground cable raceway |
| Your Production Goal | Recommended Configuration | Rationale |
|---|
| High-volume electrical conduit (16–32 mm) at lowest investment | SJZ 51/105 (18.5 kW, 120 kg/hr) | Covers the largest conduit SKU range; 120 kg/hr fills one 20-ft container order in 8–10 production days |
| Mixed production of conduit + drainage pipes (16–63 mm) | SJSZ 65/132 (37 kW, 250 kg/hr) | Wider diameter range captures both conduit and DWV markets; 250 kg/hr doubles output for the same operator count |
| Future expansion to four-cavity production | SJSZ 65/132 with oversized motor | The 37 kW motor and flow distributor can be upgraded to a four-cavity die head, doubling output again without replacing the extruder |
The SJZ 51/105 at 120 kg/hr produces approximately 960 kg per 8-hour shift; the SJSZ 65/132 at 250 kg/hr produces 2,000 kg per shift. Translating to finished pipe: for 25 mm OD × 1.5 mm wall conduit (≈0.15 kg/m), the 65/132 produces roughly 13,300 meters per shift — enough to fill one 20-foot container with conduit coils approximately every 7 production days. This is the metric that matters for export order planning.
MOQ is 1 set. Each line is configured to your target pipe diameters, die inserts, and local voltage. You are not required to purchase calibration sleeves for diameters you do not currently sell — start with the sizes your market demands and order additional sleeves when you expand your catalog.
Yes. The line carries CE certification (Machinery Directive 2006/42/EC) and is built under ISO 9001:2015. The resulting pipe can be tested to ISO 1452 (UPVC pressure pipes), ISO 3633 (soil and waste discharge), IEC 61386 (conduit systems), and ASTM D1785 / D2665. We deliver the full technical dossier — material certificates, electrical schematics, CE declaration — for your local certification body.
Standard delivery: 45–55 working days from deposit. Installation and commissioning: 5–7 working days with remote video guidance. Your first-specification pipe is produced during commissioning, not weeks later during trial-and-error. Total time-to-revenue: approximately 60–70 working days.
Yes, with caveats. The conical twin-screw extruder can process dry blend containing up to 20–25% clean post-industrial PVC regrind without screw modification, provided the regrind particle size is ≤ 2 mm and PVC content is verified. Above 25% or with post-consumer material, we recommend the vented barrel option with a vacuum degassing pump to extract volatiles that cause surface roughness and bubbles. The PLC stores separate temperature profiles for virgin and recycled blends — recycled typically requires 5°C–10°C lower processing temperatures to prevent degradation of reprocessed stabilizers.
24-month warranty on gearbox, motor, PLC, VFDs, and electrical cabinet from bill of lading date. Wear components (screws, barrel, die heads, calibration sleeves, cutter blades, haul-off pads) carry 12 months. Warranty support: video diagnosis within 48 hours, replacement parts via DHL Express at our cost. The PLC includes a remote-access module so our engineers can diagnose issues without waiting for a site visit. For real-world reliability data, see our customer stories on the news page.
USD 35,000–75,000 FOB Shanghai, depending on extruder model, die insert set size, and optional equipment (auto stacker, gravimetric feeder, vented barrel). The SJZ 51/105 configuration at the lower end suits conduit-only production; the SJSZ 65/132 at the higher end covers the full 16–63 mm range with double the output. A detailed quotation with BOM and factory layout arrives within 3 working days of your specification. Contact ceo@cxsljx.com.
SJZ 51/105: 22 m × 5 m, ceiling 4 m, 18.5 kW + auxiliaries. SJSZ 65/132: 28 m × 6 m, ceiling 4.5 m, 37 kW + auxiliaries. Utilities: 380V/50Hz 3-phase (customizable), compressed air 0.6 MPa (1.5 m³/min), cooling water recirculation 8–12 m³/hr. Standard 200 mm concrete floor — no special foundation.
If you exclusively produce electrical conduit (16–32 mm), the SJZ 51/105 at 120 kg/hr is the cost-optimal entry point — it covers the full conduit range and fills export orders efficiently. If you also produce drainage pipes up to 63 mm or need higher volume for large distribution contracts, the SJSZ 65/132 at 250 kg/hr provides the diameter range expansion and throughput that a single-operator line should deliver. The 65/132 also preserves a future upgrade path to four-cavity production without replacing the extruder.
Standard: dual laser OD gauges (one per strand, ±0.02 mm), melt pressure transducer with alarm thresholds, per-zone temperature PID display, and digital meter counters. Each strand's OD is displayed side-by-side on the HMI so the operator sees both pipes' status at a glance. For offline QC, we recommend adding an impact tester (ISO 3127), a flattening test jig, and a Vicat softening point apparatus. All QC equipment is available as a bundled package with calibration training.
Yes — this is a designed upgrade path, not an afterthought. The SJSZ 65/132 extruder's 37 kW motor and 250 kg/hr plasticizing capacity are sized to feed a four-cavity die head. The upgrade involves: replacing the two-cavity die head and flow distributor with a four-cavity unit, adding two more calibration tube pairs, two more haul-off belt units, and two more cutters. The PLC is pre-configured for four-strand control — no PLC replacement needed. This means your initial investment is protected: start with two-cavity to match your current order book, then double output when your sales volume justifies it, without buying a second extruder.
(a) Remote video-guided installation covering mechanical assembly, electrical connection, PLC commissioning, and first-batch trial — standard with every line. (b) Operator training via video call until your team runs independently. (c) Lifetime technical support via WhatsApp/WeChat/email at ceo@cxsljx.com, 24-hour response. (d) On-site engineer dispatch at USD 200/day (customer covers airfare and accommodation) for process optimization or new-die commissioning. (e) Spare parts express shipping from depots in Egypt, Nigeria, Vietnam, and India. For businesses exploring plastic recycling integration, our engineers advise on regrind-compatible screw configurations.
Independent calibration is genuine, not marketing language — each tube's vacuum, water flow, and temperature are physically separated with individual plumbing and sensors, verified by serial-numbered FAT test reports showing both strands' OD traces over a 60-minute production run.
Future-proof extruder sizing — the SJSZ 65/132's motor and throughput are deliberately oversized for two-cavity operation, so your upgrade path to four-cavity production preserves your extruder investment.
Western European engineering heritage — the line's architecture is derived from technology partnerships with German and Italian extrusion OEMs, adapted and cost-optimized for competitive manufacturing markets.
Transparent pre-order engineering — receive a dimensioned 2D factory layout drawing with all utility connection points, dual-strand material flow diagram, and recommended operator workstation positions before placing your order.
Ready to double your small-diameter PVC pipe output per square meter?
Step 1 — Define Your Market: Email ceo@cxsljx.com with your target pipe diameters (mm), desired daily output (kg/shift), and which pipe types you produce (conduit, drainage, water supply). Response within 24 hours.
Step 2 — Review Your Customized Proposal: Within 3 working days, receive a quotation with itemized BOM, dual-strand factory layout drawing, die insert specification sheet, and delivery timeline — all matched to your production targets.
Step 3 — Witness Both Strands Running: Before shipment, we conduct a live FAT producing your pipe specification on both cavities simultaneously, with independent OD traces and calibration data recorded and shared as video documentation.
Step 4 — Launch Dual-Strand Production: Our engineers guide installation via real-time video, commission both cavity controls, and supervise the first full production shift to ensure both strands deliver dimensionally identical, specification-grade pipe.
Contact us now: ceo@cxsljx.com | +86 159 5118 7228 | Chenxing Machinery
