Introduction and Calibration Overview
Purpose and Core Challenge
The main purpose of calibration is to precisely adjust the position of the knitting elements (such as sinkers or the dial needle bed) on the Dial relative to the Cylinder.This ensures that the dial needles and cylinder needles move accurately and synchronously during knitting, preventing mutual collision or the formation of incorrect loops.
Tools and Measurement
The Dial Gauge is used to check the Radial Runout and Vertical Levelness of the dial assembly, ensuring the smoothness of its circular movement.“The big gauge is at 0” describes the measured deviation, which is controlled within a specified tolerance (often a few microns) by the “rocking” (adjustment) action.
Calibration Principle and Objectives
Definition and Requirement: Radial Runout refers to the horizontal deviation of the dial’s circumference relative to the machine’s central axis during rotation. This deviation must be controlled within an extremely small tolerance (typically required to be less than 0.05 mm).
Impact: Excessive Runout results in inconsistent horizontal clearance between the dial and cylinder needles. This causes needle-to-needle scraping or collision, which is the primary cause of broken needles, sinkers, and damage to the knitting system
Calibration Principle and Objectives
Definition and Requirement: Radial Runout refers to the horizontal deviation of the dial’s circumference relative to the machine’s central axis during rotation. This deviation must be controlled within an extremely small tolerance (typically required to be less than 0.05 mm).
Impact: Excessive Runout results in inconsistent horizontal clearance between the dial and cylinder needles. This causes needle-to-needle scraping or collision, which is the primary cause of broken needles, sinkers, and damage to the knitting system
Vertical Levelness
Definition and Requirement: Vertical Levelness is the degree of parallelism between the dial needle bed and the top surface of the cylinder. This parameter determines the synchronized vertical working position of the dial and cylinder needles.
Impact: Vertical Levelness deviation directly affects the loop formation process. Incorrect vertical positioning can lead to inaccurate stitch transfer, especially when knitting double-knit structures like Rib. This results in severe defects like uneven fabric texture, barriness, or dropped stitches, significantly impairing fabric quality.
Specific Operating Procedures and Mechanism
| Location: On a double-knit circular machine, the adjustment mechanisms for the Dial are typically situated on the outer side of the Dial Support Ring or Dial Plate Holder. |
| Radial Runout Adjustment: Radial runout is primarily corrected by adjusting the Eccentric Blocks or fastening bolts on the support structure. Operators eliminate horizontal deviation by loosening and tightening these bolts to fine-tune the dial’s center. |
| Vertical Levelness Adjustment: Vertical levelness adjustment relies on the vertical adjustment bolts located on the dial support, which precisely control the axial (vertical) height of the dial. |
Vertical Levelness Correction Procedure
| 1. Locate Initial Deviation: Select a fixed reference point on the cylinder and mount the dial gauge, allowing the probe to contact the dial’s knitting surface. Rotate the machine one full turn, recording the minimum and maximum deviation values. |
| 2. Loosen Fasteners: Loosen all locking bolts on the dial support ring, but keep them slightly snug to ensure the dial can still be micro-adjusted. |
| 3. Eccentric Adjustment: Use the vertical adjustment bolts or eccentric blocks on the support structure to micro-adjust at the point of maximum deviation (the high spot). The “rocking” action in the video refers to this critical fine-tuning. |
| 4. Multiple Re-checks and Fastening: After each adjustment, re-rotate the machine and re-measure the deviation. Continue adjusting until the deviation meets the specified tolerance requirements, then uniformly and slowly tighten all locking bolts. |
Precision Acceptance and Maintenance
| Tolerance Requirement: The radial runout and vertical levelness tolerance of the dial relative to the cylinder are the final standards for calibration acceptance. Typically, high-quality double-knit circular machines require a tolerance between 0.01 mm and 0.03 mm. |
| Acceptance Procedure: After calibration, high-precision dial gauges should be used for re-checking at multiple points. It must be ensured that all adjustment bolts are uniformly tightened to prevent loss of precision due to loosening from high-speed operation and vibration. |
Stable Production and Routine Maintenance
| Locking Mechanism Check: Ensure all locking mechanisms provide sufficient friction and stability post-adjustment, preventing the dial position from drifting due to machine vibration or temperature changes. |
| Lubrication System: Confirm that the lubrication systems for the cylinder and dial drive sections are functioning correctly. Good lubrication is crucial for reducing mechanical wear and maintaining calibration precision, serving as the foundation for extending machine life. |
| Trial Run: After all checks, conduct a low-speed trial knit. Carefully observe the fabric quality to confirm that pre-calibration fabric defects (e.g., barriness, needle marks) have been eliminated, thereby validating the calibration result. |
Related Article
Key technologies for double-sided circular knitting machine needle plate calibration
Read moreKey technologies for double-sided circular knitting machine needle plate calibration
How a Circular Knitting Machine Releases and Lowers the Fabric (Shake-down Process)
Read moreHow a Circular Knitting Machine Releases and Lowers the Fabric (Shake-down Process)
What is paper-type yarn?
Five fabric components most easily misidentified during testing
Read moreFive fabric components most easily misidentified during testing
What are flame-retardant fibers?
What are PET, PBT, and PTT fibers? Do you know the difference between them?
Read moreWhat are PET, PBT, and PTT fibers? Do you know the difference between them?