Robot Body Cable Extrusion Line

Robot Body Cable Extrusion Line

Robot Body Cables refer to specialized cables that are directly installed inside the various joints of an industrial robot arm and move along with it. They act as the robot's "blood vessels" and "nerves," responsible for transmitting power to the joint servo motors and carrying critical signals from encoders, sensors, and other devices.

Core Characteristics

Compared to external drag chain cables, the most critical feature of robot body cables is their ability to withstand extremely complex composite stresses:
Extremely High Torsion Resistance
This is the most core requirement that distinguishes them from other cables. During operation, especially in joints like the 2nd and 3rd axis, the cables experience rotational torque in both positive and negative directions, not simply bending.
High-quality robot body cables must withstand millions of cycles (e.g., over 5 million or even 10 million) of torsion testing at angles like ±180°/m or greater without performance degradation.
Excellent Flexing Endurance
While undergoing torsion, the cables also experience frequent bending due to the arm's extension, retraction, and swinging motions. Therefore, high flexing endurance (typically also requiring a lifecycle of millions of cycles) is fundamental.
Compact and Lightweight Design
To reduce the robot arm's moment of inertia and save valuable internal space, these cables are typically designed with a smaller outer diameter and lighter weight. The internal structure is highly compact to maximize space utilization.
Low Extension and High Stability
The cable must not exhibit significant stretching deformation (low extension) under long-term stress, otherwise it would affect signal transmission stability and the robot's motion accuracy.
Anti-Interference Capability
As power lines and weak signal lines may be integrated within the same cable, excellent shielding (e.g., high-density braided shielding) is required to prevent electromagnetic interference and ensure signal integrity.
High Elasticity and Fatigue Resistance of Materials
The insulation and sheathing materials (such as PUR, TPE) must possess excellent elastic recovery, resisting cracking or permanent deformation after hundreds of millions of deformation cycles.

Common Structure

To meet the above requirements, their structure is meticulously designed:
Conductor: Uses extra-fine oxygen-free copper wires (Class 6/7 conductors), finely stranded with the thinnest wires, forming the foundation for high flexibility.
Insulation: Uses special thermoplastic elastomers (TPE) or polyurethane (PUR) to provide elastic protection while preventing cracking.
Cabling: Multiple cores are stranded together with an optimal lay length. This design is crucial for torsion performance, ensuring internal stresses are distributed evenly during twisting.
Inner Sheath: Secures the cable core structure, reducing internal friction.
Shielding: High-coverage tinned copper braided shielding, balancing flexibility and anti-interference capability.
Outer Sheath: Uses extremely wear-resistant polyurethane (PUR) material to protect the cable from minor friction against internal mechanical structures.

Robot Body Cable Extrusion Line

The robot body cable extrusion production line is a top-end complete set of equipment specifically used for manufacturing the insulation and sheath layers of robot core components—body cables. Due to the extreme requirements for torsion resistance, flexibility, and long-term reliability of robot body cables, this production line is far beyond comparable to ordinary cable equipment. It represents the high-precision level of cable extrusion technology and is a systematic engineering project involving precision machinery, polymer materials science, and automatic control. This production line uses extremely precise temperature control, tension control, and unique cooling processes to perfectly coat the conductor or cable core with special elastomer materials (such as high-performance PUR, TPE), producing cables capable of withstanding millions of complex stress cycles without performance degradation.

Core Components

A professional robot body cable extrusion production line mainly consists of the following systems, arranged according to the process flow:
High-Precision Pay-Off System
Function: Smoothly releases very fine conductors or precisely stranded cable cores.
Key Requirement: Extremely precise tension control. Minor tension fluctuations can cause conductor stretching or structural loosening, seriously affecting the final torsion resistance. Typically uses a servo-driven active pay-off system.
Conductor Preheating System
Function: Preheats the conductor before it enters the die head.
Importance: Removes moisture and increases conductor temperature, allowing the molten insulation material to bond more tightly with the conductor, significantly reducing internal stress. This is a key pre-process for ensuring the cable does not crack or wrinkle during torsion.
Core Extrusion System
a. Extruder:
Screw: Uses a deep groove, low-shear, low-compression ratio screw specifically designed for flexible materials, ensuring uniform plasticization and no degradation.
Temperature Control: Each zone employs PID precision control with minimal temperature deviation, ensuring the material is in the optimal processing state.
b. Head and Die:
Structure: Must use a crosshead or eccentric head to ensure molten material uniformly surrounds the conductor from all sides, achieving absolute concentricity. Any slight eccentricity is absolutely unacceptable.
Die: Undergoes ultra-precision machining with a very high inner surface smoothness to ensure a smooth extrusion surface and reduce stress concentration points.
Stepped Slow Cooling System
Function: This is the soul of producing high torsion-resistant cables.
Form: Usually a stepped cooling water tank over ten meters long or even longer, using hot-warm-room temperature water stages.
Principle: By slowly lowering the temperature, the sheath and insulation layer crystallize and solidify uniformly from the inside out, maximizing the elimination of internal stress. Rapid cooling causes uneven shrinkage between the inside and outside of the material, generating huge internal stress that immediately damages the cable during torsion.
Online Detection System
a. Laser Diameter Gauge/Eccentricity Gauge: Monitors outer diameter and concentricity in real-time, 100%, acting as the "eyes" for ensuring consistent quality.
b. Spark Tester: Detects the continuity of the insulation layer online, ensuring no pinhole defects.
Non-Damaging Caterpillar Haul-Off / Puller System
Function: Provides stable pulling force.
Characteristics: Uses a dual-wheel belt-type puller or a caterpillar track puller with large contact area and even pressure to avoid crushing the soft cable core.
Constant Tension Take-Up System
Function: Winds the finished cable neatly onto a reel without tension damage.
Characteristics: Uses servo motors or torque motors to achieve perfect synchronization with the haul-off, ensuring gentle and constant take-up tension.
Central Control System
Function: Integrates PLC and HMI touchscreen, serving as the "brain" of the production line.
Importance: Centrally sets, monitors, and records parameters such as speed, temperature, and tension for the entire line, achieving precision, automation, and traceability of the production process.

Robot Body Cable Extrusion Line Datasheet

Model	30	40	50	60	70	80	90	100	120	150
Screw Diameter (mm)	φ30	φ40	φ50	φ60	φ70	φ80	φ90	φ100	φ120	φ150
Screw L/D Ratio	25:1	25:1	26:1	26:1	26:1	26:1	26:1	25:1	25:1	25:1
Extrusion Amount (kg/hr)	25	40	70	100	140	200	250	320	450	650
Outlet Wire (mm)	0.2-1	0.4-3	0.8-5	1-8	2-15	3-25	5-35	8-60	10-80	15-120
Total Power (KW)	18	20	25	33	40	55	63	120	165	220
Traction Power (KW)	2.2	2.2	4	4	4	5.5	5.5	11	11	15
Production Speed (m/min (Max.))	600	600	600	500	500	300	300	100	80	60
Take-up Spool (mm)	φ200-400	φ300-500	φ400-630	φ400-630	φ500-630	φ800-1000	φ800-1250	φ1000-2000	φ2000-2500	φ2500-3150

Robot Body Cable Extrusion Line Application

The robot body cable extrusion production line is a paradigm in the field of high-end equipment manufacturing. Its technical core lies in "eliminating internal stress" and "guaranteeing absolute precision." Only through the "slow work yields fine products" approach of the slow cooling process and precision control across the entire line can the "lifeline" that meets the long-term, high-speed, and high-load movement requirements of robots be produced. This production line is specifically used to manufacture the following top-end cable products:
Core Application: Internal Cables for Industrial Robot Joints
Specifically produces torsion-resistant cables for the internal components of robot axes 1 to 6. These cables need to undergo over ±180° torsion movements millions of times along with the joints, pushing the process requirements of the production line to the peak.
High-End Application: Collaborative Robot Body Cables
Collaborative robots require cables that are thinner, lighter, and have a smaller bending radius. The production line must possess the capability to produce ultra-fine diameter, ultra-high flexibility cables.
Other Applications: Special Cables with Stringent Requirements for Torsion Resistance and Flexibility
Such as: encoder feedback cables inside precision servo motors, cables for medical device robotic arms with high dynamic performance, etc.