GB 20055-2006 PDF in English
GB 20055-2006 (GB20055-2006) PDF English
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Safety requirements of mill for rubber and plastics
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GB 20055-2006: PDF in English GB 20055-2006
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 71.120; 83.200
G 95
Safety Requirements of Mill for Rubber and Plastics
ISSUED ON. JANUARY 9, 2006
IMPLEMENTED ON. JULY 1, 2007
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
Table of Contents
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.
The main drafters of this Standard. Lu Jing, Li Xianglan, Liu Menghua, Luo Shaoning,
Wang Chengxu, Xia Xiangxiu.
This Standard was issued for the first time.
Safety Requirements of Mill for Rubber and Plastics
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 α0 in Figure 2. The maximum stopping angle
is the upper limit of stopping angle, indicated by αmax. The measured stopping angle is
the stopping angle measured, indicated by αm.
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 αmax of the mill rolls shall be 60°.
5.1.1.1.3 The specified stopping angle αo shall not exceed the maximum stopping
angle αmax.
5.1.1.1.4 The mill rolls shall come to rest at an angle not greater than αo 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
αmax 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 bαo, which is calculated in accordance with
the formula.
where
bαo—the horizontal distance between the trip bar and the centre of working zone,
in mm; when the value of bαo is less than 850 mm, the distance is 850 mm; bαo
shall not be less than the calculated value when αo = 30°;
αo—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...
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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