JB/T 7975-1999 JB/T 7975-1999 Rock Slab JB/T7975-1999 Standard download decompression password: www.bzxz.net

ICS25.060.20
Machinery Industry Standard of the People's Republic of China
JB/T7975-1999
Rock slab
Granite surface plate
Published on May 20, 1999
National Bureau of Machinery Industry
Implemented on January 1, 2000
JB/T7975-1999
This standard is revised on the basis of JB/T7975--95 "Rock slab". The technical content of this standard is consistent with that of JB/T7975-95, and it has only been re-edited according to relevant regulations. This standard replaces JB/T7975-95 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Standardization of Measuring Tools and Instruments. The responsible drafting units of this standard are: Pidu Tool Research Institute and Qingdao Qianshao Machine Factory. The main drafter of this standard is: Cui Wenxiang.
This standard was first issued in 1985 as GB4987-85 and was adjusted to JB/T7975-95 in April 1996.1
Mechanical Industry Standard of the People's Republic of China
Rock slab
Granite surface plate
JB/T7975-1999
Replaces JB/T7975-95
This standard specifies the type and size, technical requirements, inspection methods, marking and packaging of rock slabs with accuracy levels of 000, 00, 0 and 1.
This standard is applicable to rock slabs (hereinafter referred to as slabs) with working surfaces of 160mm×100mm~4000mm×2500mm (length×width).
Cited Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. At the time of publication of this standard, 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/T1184—1996 Form and position tolerances Provisions for unmarked tolerances 3 Definitions
This standard adopts the following definitions.
3.1 Flat plate
A flat reference device used for workpiece inspection or marking, also known as a platform. 3.2 Main fulcrum
When the flat plate contacts the mounting base or special bracket during processing, verification and use, it is used as the main supporting part. The supporting force at this time is in a static state.
3.3 Auxiliary fulcrum
When the flat plate is in use, it is an additional fulcrum to prevent overturning due to the offset of the load center of gravity or harmful deformation due to excessive load. The support reaction force on the auxiliary fulcrum should be smaller than the support reaction force on the main fulcrum. 4 Type and size
4.1 The type of the flat plate is shown in Figure 1 (the figure is for illustration only and does not represent the detailed structure). 4.2 The distribution of the main support points of the flat plate is shown in Figure 2. The auxiliary support points shown in the figure are set to prevent the flat plate from tilting due to the offset of the center of gravity during use. The auxiliary support points that cause harmful deformation due to excessive load shall be designed by the designer, but the number shall be kept to a minimum. The auxiliary support surface and the main support surface shall not be on the same plane to facilitate the adjustment of the support reaction force of the auxiliary support points. 4.3 The basic dimensions of the flat plate are specified in Table 1. Approved by the State Machinery Industry Bureau on May 20, 1999 and implemented on January 1, 2000
Auxiliary fulcrum
a (length)
JB/T 7975—1999
Main fulcrum
Marking position
H (degrees)
160×100
160×160
250 ×160
250×250
400x250
400 ×400
630 × 400
630 ×630
1000×630
1000x1000
1600×1000
1600×1600
2500×1600
4000×2500
5Technical requirements
Basic dimensions
JB/T7975-1999
Main dimensions
Allowable deviation
Basic dimensions
Allowable deviation
(reference)
The working surface of the flat plate shall not have defects such as sand holes, pores, cracks, slag inclusions, shrinkage, scratches, bumps, rust, etc. that seriously affect the appearance and performance.
5.2 The depressions or corner drops on the non-working surface of the flat plate are allowed to be repaired. 5.3 The plate should be made of fine-grained, densely structured gabbro, diabase, granite (biotite should be less than 5%, elastic modulus should be greater than 0.6×10-kg/cm*, water absorption should be less than 0.25%) and other materials, and its.T. working surface hardness should be greater than 70HS. 5.4 The maximum allowable value of the surface roughness R of the working surface of the plate is 0.32~0.63μm, and the side is 10μm. 5.5 The flatness tolerance of the working surface of the plate is as specified in Table 2. 5.6 When the flatness of the working surface of the plate is tested by the diagonal method or the grid method, its plane fluctuation amount should be tested. The plane fluctuation amount of the working surface is as specified in Table 3.
5.7 The verticality tolerance of the side of the plate to the working surface and the verticality tolerance of the two adjacent sides of the plate are both in accordance with the 12th grade specified in GB/T1184. 5.8 The concentrated load area in the center of the working surface of the plate, the applied rated load and the allowable deflection value are as specified in Table 4. 5.9 It is recommended that no carrying handles be provided for Class 000 and Class 00 flatbeds. 5.10 If threaded holes (or grooves) are provided on the working surface of Class 0 and Class 1 flatbeds, their position should not be higher than the working surface. Specifications
160 × 100
160 ×160
250 × 160
250×250
400×250
400×400
630×400
630 x 630
1000×630
1000×1000
1600×1000
1600×1600
2500 × 1600
4000x2500
Diagonal d
1The values ​​in the table are given at a standard temperature of 20°C. 2 Calculation formula:
000 level: 1x(1+
000 level:
2 ×(1 +
JB/T7975-1999
Accuracy level
0 level: 4×(1+
1 level: 8×(1+
Where: d-1. Length of diagonal line of work surface, mm. d
Surface tolerance value
3 The flatness tolerance within the range of 0.02a (maximum 20mm) from the edge of T work surface is not counted, and any point shall not be higher than E work surface. Table 3
Accuracy level
Flat plate work surface plane fluctuation
160×100
160x160
250 ×160
250×250
400×250
400×400
630× 400
630 × 630
1000×630
1000×1000
1600×1000
1600×1600
2500×1600
4000×2500
Test method
6.1 Plane fluctuation
Diagonal d
JB/T7975—1999
Circle with concentrated load area ΦD
Rated shear load|| tt||Allowable lifting value
Put the plane wave meter on the flat plate T working surface and move the plane wave meter along any straight line direction. The moving distance is half of the diagonal length of the flat plate and should not be less than 200mm. The difference between the maximum and minimum values ​​on the indicator of the plane wave meter (division value is 0.001mm) is the plane wave amount of the inspected flat plate working surface. The plane wave meter is shown in Figure 3. 100
Thin spring sheet
Micrometer
4×410
6.2 Deflection
JB/T 7975—1999wwW.bzxz.Net
Place the testing device on the working surface of the plate to be tested. When no load is applied, make the probe of the torsion spring comparator contact the working surface (a thin gauge block can be placed between the probe and the working surface to ensure accurate measurement) and record the reading. Then apply force according to the rated load specified in Table 4 and record the reading. The difference between the two readings is the deflection value of the working surface of the plate to be tested under the rated load. The testing device is shown in Figure 4. Blue code (teaching load)
Comparison
7 Marking and packaging
7.1 The plate should be marked with:
a) manufacturer's name or registered trademark;
b) product name:
c) specification and accuracy grade;
d) product serial number and manufacturing date:
e) standard number of this standard.
7.2 The packaging box of the flat panel should be marked with:
a) manufacturer's name or registered trademark;
b) product name;
c) specification and accuracy grade;
d) product serial number and manufacturing date;
e) vibration-proof, waterproof, moisture-proof and other marks.
base support
7.3 The flat panel should be treated with anti-rust treatment before packaging and should be properly packaged. The product should not be damaged during transportation due to improper packaging. 7.4 After the flat panel is verified to meet the requirements of this standard, it should be accompanied by a product certificate; the product certificate should have the standard number and product serial number of this standard.
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