This regulation is applicable to the initial verification, subsequent verification and in-use inspection of squares. JJG 7-2004 Verification Regulation for Squares JJG7-2004 Standard download decompression password: www.bzxz.net
This regulation is applicable to the initial verification, subsequent verification and in-use inspection of squares.

National Metrology Verification Regulation of the People's Republic of China JJG7—2004
Squares
Promulgated on 2004-03-02
Implementation on 2004-09-02
Promulgated by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, JJG7—2004
Verification Regulation
ofSquares
JJG7—2004
Replaces JJG61—1980
JJG7—1986
This regulation was approved by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China on March 2, 2004, and came into effect on September 2, 2004.
Responsible unit:
Main drafting unit:
Participating drafting unit:
National Technical Committee for Geometric and Angle Metrology Shaanxi Institute of Metrology and Testing
Xi'an University of Architecture and Technology
CESI Metrology and Testing Center
Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences This regulation is entrusted to the National Technical Committee for Geometric and Angle Metrology to be responsible for the interpretation of this regulation. Main drafters:
Wang Caixia
Wang Ping'an
Participating in the drafting Strawman:
Li Jiangyun
Liu Yanan
JJG7—2004
(Shaanxi Institute of Metrology and Testing)
(Shaanxi Institute of Metrology and Testing)
(Xi'an University of Architecture and Technology)
(Shaanxi Institute of Metrology and Testing)
(CESI Metrology and Testing Center)
(Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences) Scope·
References
3 Overview
4 Planning Measuring performance requirements
JJG7—2004
4.1 Surface roughness of measuring surface, base surface and side surface4.2
Flatness of measuring surface and base surface
Straightness of measuring surface
Parallelism between base surfaces
Verticality of side surface relative to base surface.
5Verticality of α and β angle measuring surface relative to base surface4.6
Indication error of linear steel square
General technical requirements
6 Control of measuring instruments|| tt||Verification conditions
Verification items·
Verification methods·
Handling of verification results
Verification cycle
Appendix A Gap method and direct measurement method
Appendix B Format of the inner pages of the verification certificate
Appendix C Format of the inner pages of the verification result notification
1 Scope
JJG7—2004
Verification procedure for square rulers
This procedure applies to the initial verification, subsequent verification and in-use inspection of square rulers. 2 References
This specification refers to the following documents
JJF1001—1998 General metrological terms and definitions JJF1059—1999 Evaluation and expression of measurement uncertainty JJF1094—2002 Evaluation of measuring instrument characteristics GB/T6092—2004 Square
When using this specification, attention should be paid to using the current valid versions of the above referenced documents. 3 Overview
The square is a commonly used measuring tool in inspection and marking work. It is used to check the verticality of the workpiece or to calibrate the verticality of the longitudinal and transverse guide rails of the instrument and machine tool. It is usually made of steel, cast iron or granite. According to its structural form, it can be divided into cylindrical square (Figure 1), rectangular square (Figure 2), triangular square (Figure 3), knife-edge square (Figure 4), cast iron square (Figure 5), wide seat square (Figure 6), flat square (Figure 7), and line steel square (Figure 8). Its basic dimensions, accuracy levels and indication errors are shown in Tables 1 to 8 respectively. Measuring pad surface
Cylindrical square
Table 1 Basic dimensions and accuracy levels of cylindrical squares Accuracy level
Basic dimensions
00 level, 0 level
Measuring scene surface
Rectangular square
Knife-edge rectangular square
Accuracy level
Basic dimensions
JJG7—2004
Measuring egg surface
Figure 2 Rectangular square
Table 2 Basic dimensions and accuracy levels of rectangular squares Accuracy level
Basic dimensions
Accuracy level
Basic dimensions
Measuring surface
Side,|| tt||Figure 3 Triangular square
00 grade, 0 grade, 1 grade
00 grade, 0 grade
Basic dimensions and accuracy grades of triangular squares00 grade, 0 grade, 1 grade
Knife-edge square
Wide seat knife-edge right angle
Cast iron square
Measuring surface
Such as measuring surface
JJG7—2004
Figure 4 Knife-edge square
Measuring surface
Table 4 Basic dimensions and accuracy grades of knife-edge squaresAccuracy grades
Basic dimensions
Accuracy grades
Basic dimensions
0 grade, 1 grade|| tt||Grade 0, Grade 1
Table 5 Basic dimensions and accuracy grades of cast iron squaresAccuracy grades
Basic dimensions
Figure 5 Cast iron squares
Grade 0, Grade 1
Measuring surface
Figure 6 Wide seat squaresbzxZ.net
Accuracy grades
Plane right angle
Ruler and flat
Surface right angle ruler with seat
Basic dimension H
Indication error
JJG7—2004
Table 6 Basic dimensions and accuracy grades of wide seat squaresGrade 0
Figure 7 Flat squares
Table 7 Basic dimensions and accuracy grades of flat squares Accuracy level
Measuring surface
Grade 0, Grade 1, Grade 2
Tide crab surface
Figure 8 Linear steel square
Basic dimensions and indication error of linear steel square150
Measuring surface dimensions
>500~1600
Measuring surface dimensions
JJG7—2004
Table 9 Surface roughness of measuring disk surface, base surface and side surface Surface roughness of measuring surface and base surface R,/um0 level
Verticality of measuring disk surface and base surface,
α, βVerticality of measuring surface relative to base surface/μm
Note: The flatness of the base surface is not allowed to be convex.
Linear steel square
Surface roughness R./um
Flatness, straightness and parallelism
Flatness or straightness/um
Parallelism between base surfaces/um
Verification items
JJG7-2004
Flatness of cast iron squareNumber of scraped contact pointsGrade 0
Number of contact points in a square area of ​​25mm×25mmDifference in the number of contact points in any two squares (25mm×25mm)Table 12
Size of measuring surface H
≥25 points
Accuracy level
Vertical of linear steel square Degree, flatness, straightness and parallelism Perpendicularity of measuring surface to base surface
Size of measuring surface H/mm
Flatness or straightness of measuring surface
Perpendicularity of side surface to base surface
Perpendicularity of side surface to base surface/um
≥20 points
Parallelism between base surfaces
Size of measuring surface 1/mm
Metrological performance requirements
JJG7—2004
Table 13 (continued)
Perpendicularity of side surface to base surface/um
Surface roughness of measuring surface, base surface and side surface 4.1
Should not exceed the requirements of Table 9.
4.2 Flatness of measuring surface and base surface
4.2.1 The flatness of the square rulers of the structural forms of Figures 1 to 7 shall not exceed the requirements of Table 10. 4.2.2 The number of scraping contact points for the flatness of cast iron squares is shown in Table 11. 4.2.3 The flatness of wire-grained steel squares shall not exceed the provisions of Table 12. 4.3 Straightness of measuring surface
The straightness of squares in the structural form of Figure 1, Figure 2 (b), and Figure 4 shall not exceed the provisions of Table 10. The straightness of wire-grained steel squares shall not exceed the provisions of Table 12. 4.4 Parallelism between base surfaces
The parallelism of squares in the structural form of Figure 4, Figure 6, and Figure 7 shall not exceed the provisions of Table 10. The parallelism of wire-grained steel squares shall not exceed the provisions of Table 12. 4.5 Verticality of side surface relative to base surface
The verticality of square rulers of the structure of Figures 2 to 7 shall not exceed the provisions of Table 13. 4.6 Verticality of α and β angle measuring surface relative to base surface The verticality of square rulers of the structure of Figures 1 to 7 shall not exceed the provisions of Table 10. Linear steel square rulers shall not exceed the provisions of Table 12.
4.7 Indication error of linear steel square rulers
The indication error of the line from any scale line to the edge or end of the ruler shall not exceed the provisions of Table 8. 5 General technical requirements
5.1 Newly manufactured square rulers shall not have defects such as rust, magnetism, bruises, cracks, sand holes, burrs, etc. The non-working surface of cast iron square rulers shall be sand-cleaned and painted.
JJG7-2004
5.2 The non-working surface of the square ruler must have the manufacturer's name or trademark, MC mark and factory number. 5.3 For the square rulers that are subsequently calibrated and inspected during use, appearance defects that do not affect the measurement accuracy are allowed. 6
Control of measuring instruments
Control of measuring instruments includes: initial calibration, subsequent calibration and inspection during use. 6.1 Calibration conditions
6.1.1 Environmental conditions
6.1.1.1 Indoor temperature (20±5)℃
6.1.1.2 Temperature equilibration time is not less than 2h. 6.1.1.3 Before calibration, the square ruler to be inspected and the calibration equipment should be placed on the flat plate at the same time. 6.1.2 Calibration equipment
See Table 14 for calibration equipment.
Table 14 List of calibration equipment
Name of standard instrument
Surface roughness comparison sample
Knife edge ruler
Micrometer
Straight collimator
Standard square iron
Wide seat square
Cylindrical square
Grinding surface flat ruler
Micrometer
Lever caliper
Steel ruler
Straight ruler
R.( 0.10~1.60)μm
≤2000mm
≤500mm
Graduation value 0.001mm
≤500mm
(0.02~0.50)mm
≤1000mm
(0~1)mm
≤200mm
≤2000mm
Note: "MPE" in the table means maximum permissible indication error. 9
Technical requirements
00 grade, 0 grade, 1 grade, 2 grade
0 grade, 1 grade
1 grade or 4 grade
MPE≤+1μm
Mutual verticality≤1.5m
00 grade, 0 grade
Flatness≤1um
Indication error≤5μm
MPEg+2um
MPEg≤±0.15mm
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