Some standard content:
ICS 73.100.99
Record number: 2135-1998
Coal Industry Standard of the People's Republic of China
MT/T72—1998
Scraper bars for the twin outboard chain conveyors
Scraper bars for the twin outboard chain conveyors1998-11-10 Issued
State Coal Industry Bureau
1999-04-01 Implementation
MT/T72-1998
This standard has made some changes to the important technical contents of the MT72-1991 version: in terms of definition, "bending test\ is changed to force-deflection test", "bending load is changed to\strength rating", and in terms of product type and size, the 30×10834×126mm (to be determined) specification is cancelled. In the inspection rules, the inspection types are divided into factory inspection and type inspection. Factory inspection shall be carried out in accordance with the secondary sampling scheme for positive belt inspection specified in GB2828-1987 "Batch Inspection Count Sampling Procedure and Sampling Table (Applicable to Inspection of Continuous Batch)", and type inspection shall be carried out in accordance with the secondary sampling scheme specified in GB2829-1987 "Periodic Inspection Count Sampling Procedure and Sampling Table (Applicable to Inspection of Stability of Production Process)". This standard shall replace MT72-1991 standard from the date of entry into force. This standard is proposed by the Industry Management Department of the State Coal Industry Bureau. This standard is under the jurisdiction of the Coal Industry Coal Mine Special Equipment Standardization Technical Committee. This standard was drafted by the Taiyuan Branch of the General Coal Research Institute. The main drafters of this standard are Qian Guansheng, Chang Yali, and Yin Xiaoyu. This standard was first issued in August 1983, revised for the first time in January 1991, and revised for the second time in October 1997. This standard is entrusted to the Scraper Conveyor Branch of the Coal Industry Coal Mine Special Equipment Standardization Technical Committee for the interpretation. 1 Scope
Coal Industry Standard of the People's Republic of China
Scraper bars for the twin
outboard chain conveyors
MT/T72—1998
MT72-91
This standard specifies the type, size, technical requirements, test methods, inspection rules, marking and packaging of scrapers for twin-chain scraper conveyors (hereinafter referred to as scrapers).
This standard applies to scrapers for twin-chain scraper conveyors and twin-chain scraper transfer machines. This standard does not apply to cast scrapers.
2 Cited Standards
The provisions contained in the following standards constitute the provisions of this standard by reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB28281987 Count sampling procedure and sampling table for batch inspection (applicable to inspection of continuous batches) GB2829-1987 Count sampling procedure and sampling table for periodic inspection (applicable to inspection of stability of production process) GB/T3414-1994 Hot-rolled special-shaped steel for coal mining machinery GB/T12718-1991 High-strength round link chain for mining MT/T150-1997 General technical conditions for packaging of scraper conveyors and transfer machines 3 Definitions
This standard adopts the following definitions.
3.1 Twin outboard chain assembly A number of pairs of chains are connected to the scraper through an open connecting ring. 3.2 Nominal chain centres The distance between the centers of the chains in the assembly.
3.3 Force-deflection test Force-deflection test A test to determine the ability of the scraper to withstand minimum deflection and strength rating. 3.4 Minimum deflection The scraper is required to withstand deflection without cracking. 3.5 Strength rating Strength rating The force required to cause the scraper center deflection equal to 10% of the nominal center distance of the component chain. 4 Types and sizes 4.1 Types The scraper types are divided into Type 1, Type 1, Straight and N, see Figures 1, 2, 3 and 4. Approved by the State Coal Industry Bureau on November 10, 1998 and implemented on April 1, 1999 MT/T72-1998 4.2 Size The size of the scraper shall comply with the provisions of Figures 1, 2, 3, 4 and Table 1. The center section of the scraper can be made into any structure and shape within the relevant size range of the nominal center distance of the chain listed in Table 1. All other dimensions shall be selected to ensure that the scraper matches other related components, i.e., connecting ring, sprocket, middle groove, and transmission device. A
1 Type scraper dimensions
Figure 21 Type scraper dimensions
Figure 3 Type scraper dimensions
MT/T72—1998
61969202
5678908868
663009859
1669089
125062
（997）
5 Technical requirements
MT/T 72—1998
Figure 4N Type scraper dimensions
5.1 The scraper shall comply with the requirements of this standard and be manufactured in accordance with the drawings and documents approved by the prescribed procedures. A
5.2 The delivery length and allowable deviation of scraper steel with scraper height of 50mm and 65mm shall comply with the provisions of Table 2 of GB/T3414-1994.
5.3 The curvature of scraper steel with scraper height of 50mm and 65mm shall comply with the provisions of 4.3.1 of GB/T3414-1994. 5.4 The scraper surface shall not have defects such as cracks, folds, scars, slag inclusions, etc. 5.5 Forged scrapers shall not be overburned.
5.6 Force-deflection test:
Apply the strength rating specified in Table 2 to the scraper, and there shall be no visual cracks on the scraper surface. Table 2 Scraper strength rating
Nominal chain size and pitch
18×64
24×86
26×92
≥105
≥125
Strength rating
≥125
≥185
≥255
≥150
≥250
≥370
≥430
Note: The strength rating of Class B scraper is equal to 7.5% of the total breaking load value of two Class C round link chains specified in GB/T12718-1991, 15% for Class C scraper and 30% for Class D scraper.
5.7 After the force-deflection test is passed, the surface of the scraper of the inspection batch shall be coated with an anti-rust protective layer. The coating shall be uniform and the double cover shall be tight. 6 Sampling
6.1 The factory inspection of the scraper shall be in accordance with the relevant provisions of the normal inspection secondary sampling plan of GB2828-1987, and the type inspection shall be in accordance with the relevant provisions of the secondary sampling plan of GB2829-1987. 6.2 All samples shall be randomly selected from the entire batch, and the samples shall not have any coating that conceals defects. 7 Force-deflection test method
7.1 Testing machine
7.1.1 The testing machine and loading device shall be able to meet the requirements of the test process. The accuracy level of the testing machine shall not be lower than level 1. The testing machine shall be used within the applicable range shown in the test certificate of the machine. 7.1.2 The testing machine shall be calibrated once a year.
7.2 Test procedure
MT/T72-1998
7.2.1 The scraper is placed freely on the test frame of the testing machine. The span between the two supporting points shall comply with the provisions of the scraper hole center distance C. During the test, a support and loading pad of suitable shape are used to apply the test force P in the center of the span in the working force direction, see Figure 5. The contact surface of the loading pad should be a cylindrical surface with a radius of 25mm. 7.2.2 The test force P is evenly applied to the scraper under test at a maximum loading rate of 20N/mm2 per second until the scraper center deflection reaches 10% of the nominal center distance of the chain. The force indication value is read from the test instrument of the testing machine. The force when each scraper under test reaches the specified minimum deflection shall comply with the provisions of Table 2.
8 Inspection rules
8.1 Inspection classification
Test span
77777777777
Figure 5 Force-deflection test
The scraper inspection types are divided into factory inspection and type inspection. Each batch of scrapers must be inspected and qualified by the factory quality inspection department before leaving the factory. 8.2 Defect classification
The defects of scrapers are classified into Class A unqualified and Class B unqualified. When the number of Class B unqualified items is equal to 3 items, it is regarded as 1 Class A unqualified. When counting, the number of Class A unqualified items is calculated cumulatively. When the number of Class B unqualified items is less than or equal to two items, it is ignored. 8.2.1 When inspecting the scraper size, any unqualified hole center distance C in Table 1 is judged as Class A unqualified, and the rest are judged as Class B unqualified. 8.2.2 When inspecting the scraper surface quality, any visual cracks in 5.4 and 5.5 are unqualified, and the rest are judged as Class A unqualified, and the rest are judged as Class B unqualified.
8.2.3 When the scraper is subjected to the force-deflection test, any one that does not meet the requirements of 5.6 is judged as Class A unqualified. 8.3 Factory Inspectionbzxz.net
8.3.1 Dimension and Surface Quality Inspection
The scrapers produced in batches are inspected in batches of less than or equal to 500 pieces. The inspection shall comply with the provisions of the secondary normal inspection sampling plan in GB2828-1987. The sample inspection level adopts the special inspection level S-3, and the qualified quality level AQL=10. Its inspection items, inspection quantity, inspection requirements, secondary sampling judgment array, etc. shall comply with the provisions of No. 1 in Table 3. 8.3.2 Force-deflection test
a) The scrapers that have passed the dimension and surface quality inspection shall be subjected to force-deflection test. The test samples can be randomly selected from the samples that have passed the dimension and surface quality inspection;
b) The inspection of force-deflection test shall comply with the provisions of the secondary normal inspection sampling plan in GB2828-1987. The sample inspection level adopts the special inspection level S-2. Its inspection items, inspection quantity, inspection requirements, etc. shall comply with the provisions of No. 2 in Table 3. 8.3.3 Inspection transfer rules
The scraper inspection transfer rules shall be in accordance with 4.6.3 of GB2828-1987. 5
Inspection items
Dimensions and surface
Force-deflection test
MT/T72-1998
Table 3 Factory inspection sampling plan
Sample size
8.4 Type inspection
8.4.1 Type inspection shall be carried out in any of the following cases: Cumulative sample size Inspection methods and requirements
In accordance with 4.2, 5.2,
5.3, 5.4, 5.5,
5.7
In accordance with 5.6, 7. 1.1,
7.1.2 stipulates
a) Trial type identification of new products or old products transferred to the factory for production: b) After formal production, if there are major changes in structure, materials, and processes that may affect product performance; c) During normal production, an inspection is carried out every 5 years; d) When the product is discontinued for 2 years and production is resumed; e) When the factory inspection results are significantly different from the last type inspection; The qualified quality level AQL=10
Second sampling judgment array
f) When the national quality supervision agency proposes a type inspection requirement. 8.4.2 The type inspection of the scraper adopts the secondary sampling plan specified in GB2829-1987, RQL=30DL=I, and the inspection items, inspection quantity, inspection requirements, secondary sampling judgment array, etc. should comply with the provisions of Table 4. Table 4 Type inspection sampling plan
Unqualified quality level RQL=30
Inspection items
Dimensions and surface
Force-lifting test
Sample size
Cumulative sample size
Inspection methods and requirements
According to 4.2 and 5.4
According to 5.6, 7.1.1,
7.1.2
Second sampling determination array
8.5 Determination rules
8.5.1 When all the factory inspection items of the inspected scraper meet the inspection requirements, the batch of products is judged to have passed the factory inspection, otherwise the batch of products is unqualified for the factory inspection.
8.5.2 When all the type inspection items of the inspected scraper meet the inspection requirements, the batch of products is judged to have passed the type inspection, otherwise the batch of products is unqualified for the type inspection.
9 Marking and packaging
9.1 The finished forged scraper shall be marked with the manufacturer's logo in a position that does not affect the strength of the scraper. 9.2 The scraper shall be firmly tied or boxed as a separate product before leaving the factory. It shall not fall apart during transportation and shall be accompanied by a product quality certificate. The certificate shall include the quantity, specification, manufacturer, inspection date, and inspector code. 9.3 The packaging of the finished scraper shall comply with the provisions of MT/T150-1997. 6
ISBN7-5020-1703-8
9hu8750217033>
China Coal
Industry Standard
Scraper for Double-Chain Scraper Conveyor
MT/T72-1998
Coal Industry Press
(Xiaguangli, Zhiyang District, Beijing: No. 100016) Printing and Cutting
Coal Industry Press Printing Factory
Xinhua Bookstore Beijing Distribution Office
Format 88 0×1230mm
Printing sheet 5/8
Word count 11,000 words
Print run 1-235
1st edition March 1999
1st printing March 1999
ISBN7-5020-1703-8/T-652.2
Book number 4474
Violators will be prosecuted
All rights reserved
If there are any quality problems such as missing pages, reversed pages, or peeled pages in this book, our company will be responsible for replacing it with MT/T72—19981 When all the factory inspection items of the scraper under inspection meet the inspection requirements, the batch of products is judged to have passed the factory inspection, otherwise the batch of products is judged to have failed the factory inspection.
8.5.2 When all the type inspection items of the scraper under inspection meet the inspection requirements, the batch of products is judged to have passed the type inspection, otherwise the batch of products is judged to have failed the type inspection.
9 Marking and packaging
9.1 The finished forged scraper shall be marked with the manufacturer's logo in a position that does not affect the strength of the scraper. 9.2 When the scraper is shipped as a single product, it shall be firmly tied or boxed, and shall not fall apart during transportation, and shall be accompanied by a product quality certificate. The content of the certificate shall include quantity, specifications, manufacturer, inspection date, and inspection personnel code. 9.3 The packaging of the finished scraper shall comply with the provisions of MT/T150-1997. 6
ISBN7-5020-1703-8
9hu8750217033>
China Coal
Industry Standard
Scraper for Double-Chain Scraper Conveyor
MT/T72-1998
Coal Industry Press
(Xiaguangli, Zhiyang District, Beijing: No. 100016) Printing and Cutting
Coal Industry Press Printing Factory
Xinhua Bookstore Beijing Distribution Office
Format 88 0×1230mm
Printing sheet 5/8
Word count 11,000 words
Print run 1-235
1st edition March 1999
1st printing March 1999
ISBN7-5020-1703-8/T-652.2
Book number 4474
Violators will be prosecuted
All rights reserved
If there are any quality problems such as missing pages, reversed pages, or peeled pages in this book, our company will be responsible for replacing it with MT/T72—19981 When all the factory inspection items of the scraper under inspection meet the inspection requirements, the batch of products is judged to have passed the factory inspection, otherwise the batch of products is judged to have failed the factory inspection.
8.5.2 When all the type inspection items of the scraper under inspection meet the inspection requirements, the batch of products is judged to have passed the type inspection, otherwise the batch of products is judged to have failed the type inspection.
9 Marking and packaging
9.1 The finished forged scraper shall be marked with the manufacturer's logo in a position that does not affect the strength of the scraper. 9.2 When the scraper is shipped as a single product, it shall be firmly tied or boxed, and shall not fall apart during transportation, and shall be accompanied by a product quality certificate. The content of the certificate shall include quantity, specifications, manufacturer, inspection date, and inspection personnel code. 9.3 The packaging of the finished scraper shall comply with the provisions of MT/T150-1997. 6
ISBN7-5020-1703-8
9hu8750217033>
China Coal
Industry Standard
Scraper for Double-Chain Scraper Conveyor
MT/T72-1998
Coal Industry Press
(Xiaguangli, Zhiyang District, Beijing: No. 100016) Printing and Cutting
Coal Industry Press Printing Factory
Xinhua Bookstore Beijing Distribution Office
Format 88 0×1230mm
Printing sheet 5/8
Word count 11,000 words
Print run 1-235
1st edition March 1999
1st printing March 1999
ISBN7-5020-1703-8/T-652.2
Book number 4474
Violators will be prosecuted
All rights reserved
If there are any quality problems such as missing pages, reversed pages, or peeled pages in this book, our company will be responsible for replacing it with MT/T72—1998
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