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GB 20055-2006Safety requirements of mill for rubber and plastics (English PDF)

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Issued by

General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China

Level / Type

National · Mandatory

Issue date

January 9, 2006

Implementation date

July 1, 2007

Scope

GB 20055-2006 (Safety requirements of mill for rubber and plastics) is available as an English-translated PDF.

GB 20055-2006 is the Chinese standard "Safety requirements of mill for rubber and plastics". Its scope clause reads: This Standard specifies the safety requirements for two roll mills for the processing of rubber and plastics.

This Standard covers the terms and definitions, list of hazards, safety requirements and measures, and verification and information for use of safety requirements and measures of two rolls mills for the processing of rubber and plastics.

This Standard applies to all two roll mills for the processing of rubber and plastics. This Standard does not cover the safety requirements for the design of an exhaust system.

Its clauses include mm to not exceeding 2 mm;; application scope; terms and definitions; safety requirements and/or measures. It was issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on 2006-01-09 and took effect on 2007-07-01.

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Document preview — GB 20055-2006

National Standard of the People's Republic of China

ICS: 71.120; 83.200
Classification: G 95

Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China

Foreword...3
1 Application Scope...4
2 Normative References...4
3 Terms and Definitions...5
4 List of Hazards...7
5 Safety Requirements and/or Measures...10
6 Verification of the Safety Requirements and/or Measures...15
7 Information for Use...17

Foreword

All technical content of this Standard is mandatory.

This Standard corresponds to the British standard BS EN 1417.1997, Rubber and

Plastics Machines – Two Roll Mills – Safety Requirements (English version). This

Standard is nonequivalent to BS EN 1417. The major differences are as follows.

-- it cancels retractable plough in the terms and definitions, cancels the term

interpretations consistent with Chinese standards and directly adopts the

relevant terminology standard of China;

-- it changes the radian(s) to degree(s) of angle for the stopping angle;

-- it adds, in the mechanical hazards related to the mill rolls, the hazards of drawing-

in and crushing between the couplers between the mill rolls and the reducer,

between the couplers between the motor and the reducers;

-- it adds the hazards of burns and/or scalds caused by the leakage or ejection of

the rotation joints in the thermal hazards;

-- it changes the gap between the mill rolls and the stock guides from not exceeding

4 mm to not exceeding 2 mm;

-- it adds the requirements for the value of noise.

From July 1, 2007, this national standard shall be implemented for the products

manufactured; from October 1, 2007, the distribution of products which do not conform

to this national standard shall be stopped.

This Standard was proposed by China Petroleum and Chemical Industry Association.

This Standard shall be under the jurisdiction of the National Standardization Technical

Committee on Rubber and Plastics Machinery (SAC/TC 31).

The responsible drafting organization of this Standard. Dalian Bingshan Rubber &

Plastics Machinery Co., Ltd.

The contributory drafting organizations of this Standard. Shanghai Rubber Machinery

Co., Ltd., Wuxi No.1 Rubber & Plastic Machinery Co., Ltd., Beijing Research & Design

Institute of Rubber Industry.

1 Application Scope

This Standard specifies the safety requirements for two roll mills for the processing of

rubber and plastics.

This Standard covers the terms and definitions, list of hazards, safety requirements

and measures, and verification and information for use of safety requirements and

measures of two rolls mills for the processing of rubber and plastics.

This Standard applies to all two roll mills for the processing of rubber and plastics.

This Standard does not cover the safety requirements for the design of an exhaust

system.

2 Normative References

The provisions in following documents become the provisions of this Standard through

reference in this Standard. For dated references, the subsequent amendments

(excluding corrigendum) or revisions do not apply to this Standard, however, parties

who reach an agreement based on this Standard are encouraged to study if the latest

versions of these documents are applicable. For undated references, the latest edition

of the referenced document applies.

GB 5226.1-2002, Safety of Machinery – Electrical Equipment of Machines – Part 1.

General Requirements (IEC 60204-1.2000, IDT)

GB 12265.1-1997, Safety of Machinery – Safety Distances to Prevent Danger

Zones Being Reached by the Upper Limbs (eqv EN 294.1992)

GB 12265.3-1997, Safety of Machinery – Minimum Gaps to Avoid Crushing of Parts

of the Human Body (eqv EN 349.1993)

GB/T 13577-2006, Mill for Rubber and Plastics

GB/T 15706.1-1995, Safety of Machinery – Basic Concept, General Principles for

Design – Part 1. Basic Terminology, Methodology (eqv ISO/TR 12100-1.1992)

GB/T 15706.2-1995, Safety of Machinery – Basic Concepts, General Principles for

Design – Part 2. Technical Principles and Specifications (eqv ISO/TR 12100-2.1992)

HG/T 2149-2004, Measuring Method of Mill for Rubber and Plastics

HG/T 3223, Rubber Machinery – Terminology

JB/T 5438, Plastics Machinery – Terminology

3 Terms and Definitions

For the purposes of this document, the following terms and definitions and those

defined in HG/T 3223 and JB/T 5438 apply.

3.1 Principal parts of mill

Principal parts of mill in this Standard refer to parts involving safety of mill, as shown

in Figure 1.

3.2 Principal crushing zone

Principal crushing zone refers to zone extending over the full length of the mill rolls

indicated by V in figure 2.

3.3 Stopping angle

Mill is equipped with a trip bar including safety bar and control button. The stopping

angle is the angle through which the mill rolls rotate from the actuation of the trip bar

until the rolls have come to rest. The specified stopping angle is specified by

mechanical design, related to the conditions of machine unloaded and machine

running at maximum speed, indicated by alpha0 in Figure 2. The maximum stopping angle

is the upper limit of stopping angle, indicated by alphamax. The measured stopping angle is

the stopping angle measured, indicated by alpham.

3.4 Safety limit

For two roll mills equipped with a trip bar, the safety limit is the vertical plane indicated

by line S in figure 2 demarcating the zone which is unsafe for operators who can reach

into it without actuating the trip bar.

3.5 Stock guide

Stock guide can be divided into fixed type and movable type which is installed on both

sides of mill rolls and used to prevent material in process from going beyond the mill

roll end (see Figure 1, location 7).

3.6 Strip cutting device

A device, equipped with rotating or stationary blades, to cut off strips of the material

from a mill roll and send to stock blender or next procedure (see Figure 1, location 3).

5 Safety Requirements and/or Measures

5.1 Mechanical hazards related to mill rolls

5.1.1 Hazard of drawing-in and crushing between the mill rolls during normal (forward)

operation.

5.1.1.1 The trip bar emergency stop protection shall satisfy the following

requirements.

5.1.1.1.1 For the installation of the machine, the top of the mill rolls shall be at a

height of not less than 1300 mm above the normal standing level of the operator.

5.1.1.1.2 The maximum stopping angle alphamax of the mill rolls shall be 60°.

5.1.1.1.3 The specified stopping angle alphao shall not exceed the maximum stopping

angle alphamax.

5.1.1.1.4 The mill rolls shall come to rest at an angle not greater than alphao after

actuation of the trip bar.

5.1.1.1.5 The mill rolls shall automatically come to rest at an angle not greater than

alphamax in the event of a power failure.

5.1.1.1.6 The trip bar shall be positioned in accordance with the following

requirements.

a) the trip bar shall extend over the full length of the rolls.

b) the trip bar (see Figure 4) shall be positioned at a distance a more than 1115 mm

above the operator's normal standing level;

c) the horizontal distance b (see Figure 4) between the trip bar and the centre of

working zone shall not be less than balphao, which is calculated in accordance with

the formula.

where

balphao—the horizontal distance between the trip bar and the centre of working zone,

in mm; when the value of balphao is less than 850 mm, the distance is 850 mm; balphao

shall not be less than the calculated value when alphao = 30°;

alphao—the specified stopping angle, in °;

D—the diameter of mill rolls, in mm.

3—interlocking guard with guard locking

Figure 5 -- Examples of Guards of Small Two Roll Mill

5.1.2 Hazard of drawing-in and crushing between the mill rolls during reverse

operation

5.1.2.1 Automatic reverse movement

When the trip bar is actuated, automatic reverse movement of the mill rolls is actuated

within 2 s to prevent human body from getting into the area under the mill rolls; the two

roll mill shall be as specified in 5.1.1.1.8 and 5.1.1.2.

5.1.2.2 Intentional reverse movement

Intentional reverse movement of the mill rolls shall only be possible by means of a

hold-to-run control device.

5.1.3 Hazard of drawing-in and crushing between the stock guides and the mill rolls

The gap between the mill rolls and the stock guides shall not exceed 2 mm.

5.1.4 Hazards resulting from loss of braking efficiency

a) The braking system shall be so designed that in the case of a power failure a

braking action will automatically bring the mill rolls to rest.

b) If the braking system consists of a mechanical friction brake only, the thermal

characteristics shall be sufficient to allow rapid dissipation of the heat produced

by the braking action.

5.2 Mechanical hazards related to com...

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 17 pages — is available in the English PDF.

Referenced standards

Normative references

GB 5226.1-2002 · IEC 60204 · GB 12265.1-1997 · GB 12265.3-1997 · GB/T 15706.1-1995 · ISO/TR 12100 · HG/T 2149-2004 · HG/T 3223

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