This standard specifies the shape and position tolerances (hereinafter referred to as "shape and position tolerances") of sewing machine parts. This standard applies to sewing machine parts. The shape and position tolerances of GB/T 4249 are used in the drawings. QB/T 1511-1992 Shape and position tolerances of sewing machine parts QB/T1511-1992 Standard download decompression password: www.bzxz.net

Light Industry Standard of the People's Republic of China
Unmarked shape and position tolerances for sewing machine parts QB/T 1511.. 1992
This standard refers to the international standard ISO2768-2:1989 "General tolerances for dimensions without tolerances - Part 2: General tolerances for shape and position".
1 Subject content and scope of application
This standard specifies the unmarked shape and position tolerances on sewing machine part drawings (hereinafter referred to as "form and position tolerances"). This standard applies to sewing machine machining parts, and the drawings adopt the unmarked form and position tolerances of the measured elements of each item of form and position tolerances of GB/T4249.
2 Reference standards
GB/T1184 Form and position tolerances
GB/T1958 Form and position tolerances
GB/T4249 Tolerance Principles
3 Terms
3.1 Shape Tolerance
Provisions for Unspecified Tolerances
Testing Provisions
Single·The total amount of variation allowed for the actual shape of the required part, including six items: straightness, flatness, roundness, cylindricity, line contour and surface profile. This standard does not specify the unspecified tolerance values ​​for the cylindricity, line contour and surface contour of parts. 3.2 Position Tolerance
The position of the associated actual element is relative to the base The total amount of variation allowed by the standard includes the three items of parallelism, perpendicularity and inclination as orientation tolerances, the three items of coaxiality, symmetry and position as positioning tolerances, and the two items of circular runout and total runout as runout tolerances. This standard does not specify the unspecified tolerance values ​​of the inclination, coaxiality, position and total runout of parts. 4 Basic provisions
4.1 Provisions for unspecified geometric tolerances of measured elements 4.1.1
The unspecified tolerances of straightness and flatness are selected according to Table 1. Table 1
Main parameters 1. And basic size segmentation
>10～30
≥30～100
>100～300
Approved by the Ministry of Light Industry of the People's Republic of China on 1992-06-08
Value, mm
Implementation on 1993-02-01
Main parameter L and basic size segmentation
>300～1000
>1000～2000
QB/T 1511 --- 1992
Continued Table 1
Unspecified tolerance
Value, mm
Note: () The main parameter L in the table, for straightness, represents the nominal length of the measured straight line; for flatness, it represents the nominal length of the longer side of the rectangular plane, or the nominal length of the diameter of the circular plane.
②The tolerance grade code in the table (the same below): H-precision grade; K-medium grade; L-rough grade. 4.1.2 Unspecified tolerance of roundness
The unspecified tolerance value of roundness is equal to the dimensional tolerance value of the circular diameter, but shall not be greater than the unspecified tolerance value of the corresponding circular runout of the same tolerance grade specified in Table 4. Difference.
4.1.3 Unspecified tolerance of cylindricity
Unspecified tolerance value of cylindricity is not specified. Cylindricity error is controlled by tolerances or unspecified tolerances of roundness, straightness of element line and parallelism between relative element lines.
For cylindrical surfaces marked with E, the cylindricity shall comply with the provisions of the inclusion principle. 4.1.4 Unspecified tolerance of parallelism
The unspecified tolerance value of parallelism is equal to the dimensional tolerance value of the distance between parallel elements or equal to the tolerance value of the flatness or straightness of parallel elements. The larger of these two tolerance values ​​is taken as the unspecified tolerance value of parallelism. And select the longer nominal length of the two elements required to be parallel as the datum element. If the nominal lengths of these two elements are equal, any one of them can be used as the datum element.
4.1.5 Unspecified tolerance of perpendicularity is selected according to Table 2. Table 2
Main parameter L and basic size segmentation
100～300
>300～1000
>1000～2000
Note: ①The values ​​specified in the table are applicable to the unnoted tolerances for the 90° right angle. The main parameter L in the table represents the nominal length of the shorter of the two sides forming the right angle. ②
Value, mm
The longer of the two sides is used as the reference element, and the shorter side is used as the measured element. If the nominal lengths of the two sides are equal, either side
can be used as the reference element.
4.1.6 Unnoted tolerance for coaxiality
The unnoted tolerance value for coaxiality is not specified. In extreme cases, the coaxiality error can be equal to the unnoted tolerance value for radial runout given in Table 4.
7 The unnoted tolerance of symmetry is selected according to Table 3. 4. 1. 7
Main parameter B1. and its subdivision
≥100～300
≥300～1000
≥1000～2000
QB/T 1511 .: 1992
Value, mm
Note: (I) The main parameters B and L in the table represent the nominal length of the distance between the measured symmetrical elements, and the longer of the two elements required to be symmetrical is selected as the reference element. If the nominal lengths of the two elements are equal, either element can be used as the reference element. The unnoted tolerance of symmetry is applicable to the case where at least one of the two center elements required to be symmetrical is the center plane, or the axes of the two center elements required to be symmetrical are perpendicular to each other.
The unnoted tolerance of circular runout is selected according to Table 4.
Tolerance gradebZxz.net
Unindicated tolerance value, mm
Note: () The table gives the unindicated tolerance values ​​for radial, axial and circular runout of any rotating surface. L
②) If the support surface is specified on the drawing, the support surface shall be used as the datum element; if the support surface is not specified on the drawing, the longer of the two related elements to be inspected shall be used as the datum element: if the nominal lengths of the two elements are equal, either element can be used as the datum element.
4.2 Selection of tolerance grade of measured elements
4.2.1 Grade H shall be selected for the following ranges
Unindicated form and position tolerance of machining matching surfaces; a.
Unindicated form and position tolerance as the datum of machining process. b.
4.2.2 K-grade is used for the following ranges
Except for 4.2.1, the unformed position tolerance of the parts that need to be machined and the maximum size is less than 200mm. 4.2.3 L-grade is used for the following ranges
Except for 4.2.1, the unformed position tolerance of the parts that need to be machined and the maximum size is greater than 200mm. 4.3 Inspection and evaluation
4.3.1 Inspection method
The inspection method of the unformed position tolerance of this standard shall be in accordance with the provisions of Appendix A of GB/T1958. 4.3.2 Evaluation method
The unformed position tolerance of the machined part on the drawing shall not be used as the routine inspection content of the production workshop or factory enterprise. Only when a dispute occurs, it shall be inspected and evaluated in accordance with the provisions of this standard. If it is found that the tolerance is occasionally exceeded, it shall not be rejected as long as it does not damage the function of the part, unless otherwise specified.
4.4 Marking method
4.4.1 The number and tolerance grade code of this standard can be marked on the drawing. Example: The medium grade tolerance should be marked with QB/T1511-K4.4.2 When this standard is selected in the technical document, the number and tolerance grade code of this standard shall be quoted. For the legend of unmarked geometric tolerances, see Appendix A.
A1 Basic requirements
QB/T1511--1992
Appendix A
Legend of main parameters of geometric tolerance items, unmarked geometric tolerance items, unmarked tolerance values ​​and datum elements (reference)
A1.1 The main parameter drawings of geometric tolerance items shall comply with the provisions of Appendix A of GB/T1184. A1.2 Unindicated geometric tolerance items, unindicated tolerance values ​​and datum elements Refer to Figure A1. The symbols, numbers and letters in the double-dotted rectangular frame on the drawing represent the unindicated geometric tolerance items, unindicated tolerance values ​​and datum codes of the parts. 82
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Additional instructions:
QB/T1511..1992
This standard is issued by the Quality Standards Department of the Ministry of Light Industry. This standard is under the jurisdiction of the National Sewing Machine Standardization Center. This standard was drafted by the South China Sewing Machine Factory. The main author of this standard is Li Songtian.
(88-80
0 years.
SM11/64\×40-3
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