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GBZ129-2016 English PDF

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GBZ129-2016: Specifications for individual monitoring of occupational internal exposure
Status: Valid

GBZ129: Historical versions

Standard IDUSDBUY PDFLead-DaysStandard Title (Description)Status
GBZ 129-20161259 Add to Cart 9 days Specifications for individual monitoring of occupational internal exposure Valid
GBZ 129-2002RFQ ASK 5 days Specifications of individual monitoring for occupational internal exposure Obsolete

Similar standards

GBZ 117   GBZ 130   GBZ 125   GBZ 121   GBZ 120   

Basic data

Standard ID: GBZ 129-2016 (GBZ129-2016)
Description (Translated English): Specifications for individual monitoring of occupational internal exposure
Sector / Industry: National Standard
Classification of Chinese Standard: C57
Classification of International Standard: 13.100
Word Count Estimation: 63,682
Date of Issue: 2016-06-28
Date of Implementation: 2016-11-01
Older Standard (superseded by this standard): GBZ 129-2002
Quoted Standard: GB 18871; GBZ 128; GBZ/T 154
Regulation (derived from): State-Health-Announcement (2016)8
Issuing agency(ies): General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
Summary: This International Standard specifies the principles and methods for individual monitoring of internal radiation. This standard applies to occupational exposure to personal monitoring.

GBZ129-2016: Specifications for individual monitoring of occupational internal exposure

---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
GB /Z 32564-2016 Nut design guide ICS 21.060.10 J13 National Standardization Guidance Technical Document of the People 's Republic of China Nut design guide 2016-02-24 released 2016-06-01 Implementation General Administration of Quality Supervision, Inspection and Quarantine of the People 's Republic of China China National Standardization Management Committee released

Foreword

This guidance technical document is drafted in accordance with the rules given in ISO /IEC 1.1-2009. This guidance document is amended by the drafting of ISO /T R16224..2012 "nut design guidelines" (English version). The technical differences between this guidance technical document and ISO /T R16224..2012 and its causes. In the normative reference document, Standard to replace the international standard (Chapter 2), in line with our basic standards for fasteners. The guidance of the technical documents by the China Machinery Industry Federation. The guidance technical documents by the National Fastener Standardization Technical Committee (SAC/TC85) centralized. The guidance of the technical documents responsible for the drafting unit. in the machine productivity promotion center. The guidance of technical documents to participate in the drafting unit. China First Automobile Co., Ltd. Technology Center, Haiyan Yuxing nut limited liability company Division, Shanghai Jinma High-strength Fasteners Co., Ltd., Zhejiang State Inspection Technology Co., Ltd., Dongfeng Commercial Vehicle Co., Ltd. Dongfeng Commercial Vehicle Technology Center, Shaoxing Mountain High Pressure Fastener Co., Ltd. This guidance technical document is interpreted by the National Fastener Standardization Technical Committee Secretariat. Nut design guide

1 Scope

The guidance technical documents are given in accordance with GB/T 3098.2 provisions of the nut design guidelines to prevent the static tension when the emergence of snails The failure form of the tripping. This guidance document also applies to non-standard nuts or internally threaded parts (in accordance with GB/T 192). However, size Factors such as the width of the edges or other dimensions associated with the stiffness of the nut, the thread tolerances, etc., will affect the carrying capacity of the bolts and nuts. Therefore, the verification test should be carried out for the calculation results. Note. The "bolts" and "nuts" mentioned in this guidance document are used as general terms for internal and external thread fasteners.

2 normative reference documents

The following documents are indispensable for the application of this document. For dated references, the only dated edition applies to this article Pieces. For undated references, the latest edition (including all amendments) applies to this document. GB/T 192 General thread basic tooth type (GB/T 192-2003, ISO 68-1..1998, MOD) GB/T 196 Common thread basic dimensions (GB/T 196-2003, ISO 724..1993, MOD) GB/T 3098.1 Fasteners - Mechanical properties - Bolts, screws and studs (GB/T 3098.1-2010, ISO 898-1..2009, MOD) GB/T 3098.2 Fasteners Mechanical properties nuts (GB/T 3098.2-2015, ISO 898-2..2012, MOD) ISO 18265 Metal material hardness value conversion (Metallicmaterials-Conversionofhardnessvalues)

3 code

The code given below applies to this document. Asphalt actual stress cross - sectional area, mm2 Asymmetric thread nominal cross - sectional area, mm2 ASb external thread shear area, mm2 ASn internal thread shear area, mm2 C1 nut expansion coefficient C2 thread bending affects the correction factor of bolt release strength The correction coefficient of nut thread bending effect of nut thread D External thread Nominal diameter, mm D1 external thread basic diameter, mm D2 external thread basic diameter, mm D3 external thread diameter, mm DA AS corresponds to the equivalent diameter, mm D Nominal diameter of internal thread, mm D1 internal thread basic diameter, mm D2 internal thread basic diameter, mm Dc nut counterbore diameter, mm D m nut effective height or screw thread length meff, the average diameter of the counterbore section, mm F tensile load, N FBb bolt breaking load, N Fm ultimate tensile load, N Fp guaranteed load, N FS bolts and nuts connected to the trip load, N FSb external thread trip load, N FSn internal thread trip load, N Fu limit clamping force, N Fy yield clamping force, N Hc end chamfer height, mm H thread Original triangle height, mm M nut height, mm Mc thread trip failure and fracture failure probability nut critical height, mm Meff nut effective height, mm Meff, c thread tripping failure and fracture failure probability nut effective critical height, mm P pitch, mm Rm tensile strength, MPa Rmn nut tensile strength, MPa RS intensity ratio S nut side width, mm Sp Guaranteed stress, MPa X shear strength/tensile strength ratio Μth thread friction coefficient ΤBb bolt material shear strength, MPa ΤBn nut material shear strength, MPa

4 design principles

4.1 Fracture forms that may occur when bolts and nut connections are subjected to tensile loads When the bolts and nuts are subjected to an overloaded static tension, the following three types of failure occur. --- When the thread is of sufficient length, the nut or internal thread material is strong enough to break the bolt; --- When the thread screwing length is too short, nut or internal thread material strength is high, the external thread tripping; --- When the thread screwing length is too short, nut or internal thread material strength is low, the internal thread tripping. In the above fracture failure form, the bolt fracture is predictable because it indicates the full load carrying capacity of the bolts and nuts. this In addition, the local thread during the fastening process, it is difficult to find. Thus, the lack of clamping force and/or carrying capacity in service increases the risk of fracture. 4.2 Calculation of sub-failure load of bolt and nut connection 4.2.1 General rules As described in 4.1, there may be three types of failure, bolts, screws, or studs when a static tension is overloaded during nut tightening, And can be expressed by the following three kinds of failure load. --- bolt breaking load (FBb); --- External thread trip load (FSb); --- internal thread trip load (FSn). The above three kinds of load mainly depends on the height of the nut, the hardness of the nut or the tensile strength of the material, the hardness of the bolt or the tensile strength of the material The diameter, pitch, and the effective screwing length of the bolts and nut threads. In addition, the three kinds of loads affect each other, such as the increase in nut hardness will increase the external thread trip load. Alexander (EMAlexander) [5] established a mathematical model for calculating these three loads. In line with GB/T 3098.1 and The bolts and nuts of the GB/T 3098.2 should basically follow the following design principles. the coupling pair should not occur when the static tension is overloaded Trip, because such failure is not easy to be found. This means that the bolt breaking load (FBb) should be lower than the other two kinds of load values. This is the GB/T 3098.2 according to the different height and hardness, the nut is divided into type 1 and 2 reasons. 4.2.2 Bolt breaking load (FBb) 4.2.2.1 General Bolt breakage usually occurs at the middle of the uncoupled thread length of the clamping portion, so that the breaking load is independent of the nut's technical conditions. 4.2.2.2 Bolt breaking load of pure tension For bolts that conform to GB/T 3098.1, the tensile strength is equal to the ultimate tensile load divided by the nominal cross-sectional area of the thread, Formula (1). D1 --- basic thread of external thread (GB/T 196); H - Thread Original Triangle Height (GB/T 192). (1) with the nominal cross-sectional area of the workpiece As, the nominal load can be converted to tensile strength, and vice versa. Whereby the bolt is made in kind The tensile strength Rm is not exactly the same as that of its material. For example, the basic deviation of the small size bolts d1 and d2 is large, so the phase ratio Large size bolts with the same grade require higher hardness or material tensile strength. Therefore, the actual stress cross-sectional area As (instead of As, nominal) of the bolt is used in the calculation, and the actual d1 and d2 are obtained by the formula (2) However, this does not mean that the actual stress cross-sectional area of the thread is determined only by the thread geometry (diameter and diameter). Bolt bearing capacity The force is not only affected by the size, but also by the stress concentration [6] resulting in the distribution of the plastic extension in the unshaft. Unscrewed thread length Affect the distribution of plastic extension, thus affecting the bolt carrying capacity. Screws with short thread lengths are often subjected to higher tensile loads. 4.2.2.3 Bolt breaking load of torsion-pull composite VDI2230 [7] gives the formula (3) to calculate the yield clamping force Fy. Equation (3) is based on the maximum distortion energy theory and assumes that the yield torsional stresses are the same across the entire section. According to the theory, when tightened Bolt breaking load, that is, limit clamping force Fu can Rm instead of Rp0.2 and obtained. 4.2.3 Thread trip load (FSb, FSn) 4.2.3.1 Threaded tripping load for pure tension According to Alexander theory [5], FSb and FSn from (5) obtained. Where. C1 - correction factor for nut expansion; C2 --- correction coefficient of thread bending effect of bolt tension; C3 --- Thread bending affects the correction factor of nut trip strength. The relationship between C2 and C3 and the intensity ratio RS is given by Fig. 1, indicating that when the trip failure occurs, the trip load is subject to thread The strength of the part (bolt or nut) is affected, but which thread (internal or external thread) trip is determined by the RS. Note. The use of finite element analysis and experimental study [8] shows that the value calculated by the formula (6) for the smaller width of the nut is too conservative. This shows that this The design of the smaller side of the width of the nut is safer. When calculating the thread shear area with equation (5), it is assumed that 40% of the chamfer height is effective for the thread effective rotation length (ie nut effective height) meff. A internal thread tripping B External thread tripping. Figure 1 Thread bending affects the correction coefficients C2 and C3 of the trip strength According to the assumption of Fig. 2, ASb and ASn can be derived from Eq. (7) For single-sided chamfer nut, meff = m -0.6hc; for double-sided chamfer nut, meff = m -1.2hc. Description. D --- male thread nominal diameter; D1 --- internal thread basic path; Dc --- nut counterbore diameter; Hc - end chamfer height; M - nut height; Meff --- nut effective height (= thread effective rotation length). A internal and external thread. Figure 2 Hex nut effective height meff 4.2.3.2 Trip load during tightening During the tightening process, the sliding between the thread and the bearing surface increases the expansion of the nut, resulting in a decrease in the shear area of the bolt and the nut, Factors affecting the trip load, see 4.3.2.3 and 5.2. In addition, the bolt breaking load at the time of tightening [that is, Fu in equation (4)) is generally reduced by 15% to 20%. 4.3 Factors affecting the load carrying capacity of bolts and nuts 4.3.1 Influencing factors based on Alexander's theory Table 1 summarizes the influencing factors of the three possible forms of failure (see 4.2.1) according to the Alexander theory and gives a description of the three types of failure The degree of impact of the load (direct/indirect/no effect), and the direct correlation variable. Table 1 Influencing factors of the bearing capacity of bolts and nuts Item factor variable influence level FBb FSb FSn Bolt performance level (hardness) Tensile strength, Rm Shear strength, 0.6Rm Correction factor, C2, C3 ○ ○ ● Nut hardness Shear strength, 0.6Rmn Correction coefficient, C2, C3 - ○ ○ Nut height bearing area, ASb, ASn - ○ ○ Nut side edge width correction factor, C1 - ● ● Bolt thread tolerance level Actual cross - sectional area of bolt Shear area, ASb, ASn ○ ○ ○ Nut thread tolerance grade shear area, ASb, ASn - ○ ○ Nut chamfer height/angle shear area, ASb, ASn - ○ ○ Bolts/nuts D/P Actual cross - sectional area of bolt Shear area, ASb, ASn ○ ○ ○ ○ direct or significant impact. Indirect or slight impact. - no effect. 4.3.2 factors that Alexander did not consider, but could affect the load carrying capacity of bolts and nuts 4.3.2.1 Shear strength/tensile strength ratio of the material In the formula (5), the shear strength/tensile strength ratio x (= τBb/Rm or τBn/Rmn) is 0.6 for all carbon steel and alloy steel fasteners, but x Depending on the material and its performance level. VDI2230 [7] The recommended x value is shown in Table 2. Table 2 Relationship between shear strength/tensile strength ratio x and bolt performance grade specified in GB/T 3098.1 Performance level 4.6 5.6 8.8 10.9 12.9 X = τBb/Rm 0.70 0.70 0.65 0.62 0.60 It should be noted that the values in Table 2 are the conservative values calculated from Eq. (5) from the safety aspects of lower performance grade bolts (nuts). But the values of the correction coefficients C2 and C3 are empirically determined. Therefore, the effect of shear strength and tensile strength ratio x should be taken into account in equation (5). For other materials (such as stainless steel and non-ferrous metals), the value of x should be considered separately, see reference [7]. 4.3.2.2 Bolt and nut pitch deviation Based on the results of the finite element analysis [8], the thread tripping occurred initially at the first buckled thread near the nut support surface, Bolt and nut connection, where there is no pitch deviation, the smallest cut surface, the largest load. Therefore, for bolts and nuts with pitch misalignment The trip, trip load FSb and FSn will vary, because this deviation causes the load to be shared to each of the screw threads. From the thread carrying capacity It is preferable that the bolt pitch is slightly smaller than the nut pitch of the nut and the nut connection. 4.3.2.3 The coefficient of friction between the threads and the bearing surface As described in 4.2.2.2 and 4.2.3.2, when the tightening load is applied, the bolt breaking load FBb and the trip load of the bolt and nut connection FS will be reduced. The reduction of FBb is caused by the composite stress calculated by Eq. (4), where the effect of the friction coefficient (μth) between the threads is significant. The other party The decrease in FS is mainly due to the expansion of the nut due to slip during screwing. The effect of μth on it is not clear. this means The greater the μth, the higher the probability of occurrence of bolt breakage. In the design procedure of 5.2, only the friction coefficient for some ranges is allowed to have a relative reduction of 5% of the breaking load. In the future, it is proposed to introduce a breaking load (i.e., limit clamping force Fu) instead of 0.95FBb, and the fastening correction coefficient C1 'instead of C1. A Method for Calculating Bolt and Nut Connection Based on Alexander 's Theory 5.1 General rules Figure 3 summarizes the Alexander theory. The combination of bolts and nuts for the combination of specific material properties has a trip load of FS = min (FSb, FSn) and the rotation of the screw threading area, that is, the effective height of the nut meff, the number of screw threads were linear relationship with the bolt breaking load FBb turn off. Therefore, the failure of the bolt and nut connection pairs can be controlled by selecting the nut height. In Figure 3, when the trip load is exactly equal to the bolt breaking load, the nut height is defined as the nut critical height meff, c. Due to the presence of shadow Ring factor (as shown in Table 1), the trip load and the breaking load are different, so that the nut is highly distributed. So the minimum height of the nut To determine the need to take into account the possibility of each failure form. Assuming that the shear strength is 60% of the tensile strength of the bolts and nuts, the failure load can be calculated by equations (2) and (5). The Monte Carlo simulation method can be used to obtain the distribution of meff, c in Figure 3, see 5.2. Figure 3 The relationship between the failure load (FS and FBb) and the nut effective height (meff) 5.2 Specifies the minimum height of the nut The procedure for calculating the minimum height of the nut is as follows. Step 1. For nuts with bolts that specify specifications and performance levels, select the nut material to determine the minimum tensile strength, ie the lowest hardness. Step 2. Assume that each variable is normally distributed according to the deviation (6σ) given in Table 3, and within the tolerance zone, the trip is more likely occur. Step 3. Calculate the bolt breaking load FBb and the trip load FS when meff = 1D (see Fig. 3) using the random distribution of random variables. Step 4. Calculate the critical effective height meff of the nut at FS = 0.95FBb by the relationship given in Figure 3, c. Step 5. Find the nut critical effective height meff, c. Step 6. 10% meff, c as the minimum effective height of the nut meff, min. Step 7. Calculate the minimum height m min 'from the relationship given in Figure 2. Step 8. Add the tolerance and round integer value to find the maximum nut height m max. Step 9. Subtract the nut height tolerance from m max to obtain the minimum nut height m min. Table 3 assumptions about the variables Variable nut bolts Nut tensile strength Rmn 60MPa Rm 60MPa Large diameter D - d 20% tolerance Medium diameter D2 30% Tolerance d2 25% Tolerance Trail D1 50% Tolerance d3 is calculated from P and r Tooth root radius - - r 0.01P Nut Height m 60% Tolerance - - Countersink angle - 5 ° - - Dump diameter Dc 0.01D - - In step 4, the 5% breaking load reduction is caused by the torque load during the tightening process. When fastening, the fracture load is expressed by (4) The composite stress is reduced and the trip load decreases due to the expansion of the nut by the rotation of the screw thread, see 4.2.3.2. 5.3 Specifies the minimum hardness of the nut Based on the simulation analysis of the Alexander theory, the hardness range for the specified nuts can only be obtained by repeated tests. So, already Has developed a simple set of procedures to ensure the clarity of the process and the future revision of the consistency. The recommended method [9] assumes that the hardness is a given average and the minimum hardness value can be obtained using the deviations in Table 3. Not from the use of Table 3 Calculate the mean value of the variables obtained under the condition of 0.95FBb = FS. For the reverse calculation, the equation (5) is transformed into. The intensity ratio RS is obtained by using the inverse function of condition 0.95FBb = FS and C2, C3 * The tensile strength of the nut calculated by RS is converted to Vickers hardness (HV) using the conversion table in ISO 18265. 5.4 Guaranteed load Nut to ensure that the load test is carried out with a hardened man......
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