GB/T 7690.2-2013Reinforcements -- Test method for yarns -- Part 2: Determination of twist (English PDF)

Foreword

GB/T 7690 "Test method for yarns enhanced" is divided into six sections.

--- Part 1. Determination of linear density;

--- Part 2. Determination of twist;

--- Part 3. Glass fiber breaking force and elongation measurement;

--- Part 4. Determination of stiffness;

--- Part 5. Determination of glass fiber diameter of the fiber;

--- Part 6. Determination of twist balance index.

This section GB/T 27690 Part of.

This section drafted in accordance with GB/T 1.1-2009 given rules.

This Part replaces GB/T 7690.2-2001 "enhanced method for yarns Part 2. Determination of twist", and

GB/T 7690.2-2001 main differences are as follows.

--- In a broader range of applications, in addition to the original standard glass fiber coated carbon fiber and aramid fiber yarn, but also includes other

Reinforcing fibers (see Chapter 1);

--- Remove the "Reference Standards" GB/T 7690.1 and GB/T 18374, increase the ISO 2. 1973, ISO 291, and

ISO 1889 (see Chapter 2, Section 2 of the 2001 edition).

This section uses the translation method identical with ISO 1890.2009 "Enhanced yarn twist determination."

This part made the following editorial changes.

--- Consistent with the existing standard series, the standard name will be changed to "Enhanced Test method for yarns - Part 2. Twist measurement

set".

This standard normative international documents cited in the correspondence between the consistency of the following criteria.

--- GB/T 2918-1998 plastic sample conditioning and testing of the standard environment (ISO 291.1997, IDT);

--- GB/T 7690.1-2013 Reinforcements Test method for yarns - Part 1. Determination of linear density (ISO 1889.1997,

IDT).

This part of the National Standardization Technical Committee fiberglass (SAC/TC245) centralized.

This section is responsible for drafting. Nanjing Fiberglass Research and Design Institute Limited, the national glass fiber product quality supervision and inspection center.

1 Scope

GB/T 7690 provisions of this part of the glass fiber, carbon fiber, aramid fiber or other measurement method of reinforcing fiber yarn twist.

This method is suitable for yarn (a twisting), plied yarn or cable (double or multiple twisting). For plied yarns and cables, this method is usually

Only applicable to the determination of the final twist.

This method is suitable for winding yarn. If the sample is a warp beam (warp) or extracted from the fabric yarns, the test results only as a state

Instructions.

This method does not apply to fixed-length fiber products.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version suitable for use herein

Member. For undated references, the latest edition (including any amendments) applies to this document.

ISO 2. 1973 and its products textile yarn twist notation (Textiles-Designationofthedirectionof

twistinyarnsandrelatedproducts)

ISO 291 environmental standard plastic sample conditioning and testing (Plastics-Standardatmospherefor

conditioningandtesting)

ISO 1889 Determination (Reinforcementyarns-Determinationoflineardensity) reinforcing yarn linear density

3 Terms and Definitions

The following terms and definitions apply to this document.

3.1

Z twist Ztwist

S twist Stwist

Vertical Hold the yarn, if the fibers or filaments around its own axis formed a spiral to the middle portion of the letter Z is the same or S

Tilted, the corresponding called Z-twist or S-twist.

NOTE. See ISO 2. 1973 Chapter 2.

Principle 4

A sample of known length of the twist can be eliminated by untwisting, one end of which is equivalent to a fixed sample fixed, the other end of the rotation until the group

A sample of all units (yarn or monofilament) in parallel.

Record yarn twist and twist, even if the number of revolutions of the yarn length 1m eliminate twist required.

We must take into account the impact of lead on the way the test results when measuring.

When the yarn is tangential leads, twist does not change. If it is the end of the lead, the twist test values \u200b\u200baccording to the circumference of the spool and correction,

Increase or decrease depending on the yarn from the top or bottom of the package leads.