JB/T 7944-2000 This standard is a revision of JB/T 7944-95 "Sampling Inspection of Cylindrical Helical Springs". This standard specifies the sampling method for cylindrical helical springs. This standard applies to cold-rolled and hot-rolled cylindrical helical spring compression, tension springs and cold-rolled cylindrical helical torsion springs. This standard does not apply to valve springs, hydraulic springs, and springs with special requirements such as diesel engine injection pumps, governors, and injectors. This standard was first issued in 1989 as GB 1239.5-89, and the standard number was adjusted to JB/T 7944-95 in 1996. JB/T 7944-2000 Sampling Inspection of Cylindrical Helical Springs JB/T7944-2000 Standard download decompression password: www.bzxz.net
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ICS21.160 Standard of the Machinery Industry of the People's Republic of China JB/T7944-2000 Sampling procedures for inspection by attributes of coiled helical springs2000-04-24 Issued National Bureau of Machinery Industry 2000-10-01 Implementation JB/T-7944-2000 This standard is a revision of JB/T7944-95 "Sampling inspection of cylindrical bursting springs". During the revision, the original standard was edited and the main technical content remained unchanged. This standard replaces JB/T7944-95 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Spring Standardization. The drafting units of this standard: Mechanical Science Research Institute, Tianjin Spring Research Institute. Mechanical Industry Standard of the People's Republic of China Sampling procedures for inspection by attributes ofcoited helical springs1Scope This standard specifies the sampling inspection methods for the test column end family springs. This standard applies to cold-rolled and hot-rolled cylindrical helical compression, tension springs and cold-rolled cylindrical helical torsion springs. JB/T7944-2000 Replaces JB/T794495 This standard does not apply to valve springs, hydraulic springs, and springs with special requirements such as injection pumps, governors, and injectors for diesel engines. 2Referenced 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 are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T2828--1987 Batch inspection counting sampling procedure and sampling table (applicable to continuous batch inspection) 3 Defects Springs that do not meet the technical requirements specified in product technical standards, process documents, and drawings constitute defects. According to the severity of the defects, they are generally divided into: A defect item (fatal defect); B defect item (serious defect); C defect item (general defect). Spring defect items are shown in Table 1. Spring category Cold rolled compression spring Cold rolled tensile spring Cold rolled torsion spring Hot rolled shrinkage spring Hot rolled tensile spring A Defective items Decarburization, hardness Decarburization, hardness Dephosphorization, sulfurization B Defective items Spring properties, outer diameter or inner diameter |tt||Diameter, surface acid depression, permanent deformation Elastic properties, surface defects Spring properties or internal angle, Surface defects Spring properties, outer diameter or inner Diameter, surface defects, permanent deformation Elastic properties, surface defects, Water-resistant deformation Note: When there are special requirements, the fatigue life can be agreed upon by both parties. Can be used as the monthly inspection form for A defect items Approved by the National Machinery Industry Bureau on April 24, 2000 C defect items Verticality, total number of surfaces, free height Uniform hook of pitch Outer diameter, free length, hook and ring structure Partial length Outer diameter or inner diameter, inner length Torsion length Vertical point, straightness, free height Uniformity, total number of turns, pitch uniformity Outer diameter, free length Implemented on October 1, 2000 Inspection level According to the special inspection level S-4 in GB/T2828. 5 Sample size code JB/T7944—2000 The sample size code is determined according to the batch size of the inspection batch submitted and the special inspection level S-4, see Table 2. Table 2 Inspection water rate Batch range 91~150 151-500 501~1200 1201~10000 10001-35000 35001~500000 ≥500001 6 Sampling plan 6.1A Sample extraction for defective items 6.1.1 Regardless of the size of the delivery batch, the fatigue life samples of cold-rolled cylindrical springs are 4 pieces: metallographic and decarburization samples are 2 pieces, and the manufacturer can also provide 2 test (blocks). 6.1.2 Regardless of the size of the delivery batch, the fatigue life samples of hot-rolled cylindrical helical springs are 2 pieces: the metallographic and decarburization samples can be provided by the manufacturer as 2 test bars (blocks). 6.1.3 When there is a special need, it can be agreed upon by both the supply and demand parties. 6.2BC defect item sample extraction Depending on the size of the delivery batch, one, two or five normal inspection sampling plans can be adopted. 6.2.1 When the delivery batch is 2~1200 pieces, a normal inspection sampling plan can be adopted, see Table 3. 6.2.2 When the delivery batch is 1201~10000 pieces, a two-time normal inspection sampling plan can be adopted, see Table 4. 6.2.3 When the delivery batch is greater than 10000 pieces, a five-time normal inspection sampling plan can be used, see Table 5. Sample size code Sample size code Sample size code JB/T7944-2000 Sample size Sample size Sample size Note: Samples with the symbol "*" cannot be judged as qualified for the inspection batch. Table 4 Cumulative sample size Cumulative sample size Quality level AQL Quality level AQL Quality level AQL 7Quality level AQL 7.1A Defective items JB/T7944--2000 In the inspection, even if there is one spring that fails to meet the quality standards, the corresponding inspection shall be repeated for sampling. If there is still one spring that fails to meet the quality standards during this inspection, the entire batch of products shall be rejected. 7.2B Defective Items Qualified Quality Level is 4.0. 7.3C Defective Items Qualified Quality Level is 6.5. bzxz.net 8 Others 8.1 The manufacturer has the right to use any inspection procedure to control quality during the production process (including finished product warehouse acceptance inspection), but must ensure that the quality of the finished spring products meets the requirements of this standard and the relevant standards. 8.2 When the purchaser considers it necessary or economically reasonable, it may exempt the inspection of the products submitted for acceptance based on the quality reputation of the manufacturer and the quality assurance of the products previously delivered, or it may conduct acceptance inspection according to the sampling plan agreed by both parties. 8.3 The acceptance inspection items of spring products are limited to the relevant indicators specified in the relevant standards. The purchaser should focus on whether the products can meet the expected use requirements. Therefore, it can increase or reduce the random inspection items according to the specific use requirements. 8.4 When there is a dispute over the products submitted for acceptance, the purchaser must give the manufacturer an opportunity to verify. 8.5 The manufacturer must classify or repair the rejected product batches before resubmitting them for acceptance. Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.