Some standard content:
Light Industry Industry Standard of the People's Republic of China
Platform Balance
This standard adopts the International Recommendation R76-1 "Non-automatic Weighing Instruments" of the International Organization of Legal Metrology (OIML). 1 Subject Content and Scope of Application
QB/T 2087—1995
This standard specifies the product classification, technical requirements, test methods, inspection rules and marking, packaging, transportation and storage of the platform balance. This standard applies to double-pan single-lever equal-arm platform balance (hereinafter referred to as "balance"). 2 Reference Standards
GB 191 Pictorial Marking for Packaging, Storage and Transportation
JJG 99 Magnetic Code (Trial)
3 Product Classification
3.1 Product Model
3.1.1 This balance is a non-enclosed type with a scale device as the basic type. 3.1.2 The model of the basic type of balance is composed of the Chinese phonetic initials "JPT" of "pan balance" followed by a code, which is expressed as one percent of the maximum weighing capacity (in grams). 3.1.3 The modified product is followed by the modified sequence number after the above basic model, which is expressed as A-no scale, B-closed type, and C-torsion type.
Example 1: The model of a scaled, non-closed balance with a maximum weighing capacity of 100g is expressed as JPT-1. Example 2: The model of a scaled, non-closed balance with a maximum weighing capacity of 200g is expressed as JPT-2A3.2 Basic parameters
This balance belongs to the medium accuracy level (ear level), and its basic parameters are shown in Table 1. Table 1
Maximum weighing capacity
100g≤Max≤20kg
Verification division value
0.1 g≤e≤10 g
Note: The verification division value of this balance is ed (actual division value). 4 Technical requirements
4.1 Metrological performance
4.1.1 Maximum allowable error
Verification division number
n=Max/e
1000≤≤2000
Minimum weighing capacity
When the balance is adjusted to zero when unloaded, the maximum allowable error for any load between zero and maximum weighing capacity is specified in Table 2.
Approved by China Light Industry General Association on March 27, 1995
Implemented on January 1, 1996
0～500 e
>500 e~2 000 e
4.1.2 Eccentric load error
QB/T2087—1995
First calibration
The eccentric load error of the balance shall not exceed the maximum allowable error at the load. 4.1.3 Sensitivity
Maximum allowable error
In use
When the balance is unloaded or loaded, add or subtract a code with a mass equivalent to the absolute value of the maximum allowable error of the load used, and the change of the resting point of the balance pointer shall not be less than 1 scale mark. 4.1.4 Repeatability
When the same load is weighed multiple times, the difference between the results shall not be greater than the absolute value of the maximum allowable error at the load. 4.2 Maximum safe load
The balance should be able to swing normally at 125% of the maximum weighing load. 4.3 Magnetic code configuration
The balance is equipped with a 6-level (Mz-level) code. The quality of its configuration (including the scale measurement value) should be able to meet the full value requirements of the balance, and the combination of the base code should meet the requirements of Article 4 of JJG99. 4.4 The knife, knife bearing, knife baffle and pull rod of the balance should be heat treated, and the hardness requirements are: knife HRC58~62; knife bearing, knife baffle HRC62~66; pull rod HRC50~55. The surface roughness R of the working part of the force and knife bearing is 1.6μm. 4.5 The scale lines of the balance graduation plate should be clear and uniform, with a line width of 0.2~0.3mm and arranged in a fan shape. The center line and the two side lines should be longer than other scale lines, and the scale line spacing should be no less than 1mm. 4.6 The scale of the balance should be smooth and straight, the scale lines and numbers should be clear and even, the scale line width should be 0.3~0.4mm, the spacing should be not less than 1.5mm, and the mass unit should be marked on the scale. 4.7 The mass difference between the left and right weighing pans of the balance shall not exceed 0.5e.:4.8 Assembly
4.8.1 The knife shall be fastened vertically to the lever, and the three blades shall be parallel to each other. 4.8.2 The knife holder shall not be loose when assembled on the bracket, weight rack, and knife holder, and the working surface relative to the knife holder shall be in a straight line. 4.8.3 The balance screw shall be fastened to the lever; the balance nut shall be appropriately tight when rotating; when balancing without load, the balance nut shall be located in the middle of the screw.
4.8.4 The pointer shall be fastened vertically to the center of the lever, and the distance between the needle tip and the graduation plate shall not be greater than 1.5mm, and the width of the needle tip shall not be greater than the width of the scale line. When the lever swings, the limit device shall enable the maximum swing of the pointer to exceed the last scale line on both sides, the pointer tip shall be parallel to the scale line, and the pointer tip shall be able to cover 3/5~4/5 of the total length of the short scale line. 4.8.5 The connecting pin connected to the pull rod shall not rotate. 4.8.6 The starting point of the sliding weight should be aligned with the zero scale line of the scale. The sliding weight should be loose and tight when moving, and should not scratch the scale surface of the scale. The sliding weight should not move when the lever swings or is slightly impacted. 4.9 Appearance
4.9.1 The surface of the stamping part should be flat and smooth, without sharp edges, burrs and cracks. 4.9.2 The shape of the casting should be flat, without sand sticking, cracks and obvious sand holes. 4.9.3 The surface coating of the electroplated part should be uniform in color and not There should be no defects such as exposed bottom, peeling, obvious pitting, water stains, scratches, etc. 4.9.4 The surface of the painted parts should be flat and uniform in color. There should be no defects such as exposed bottom, blistering, paint hanging, paint leakage, scratches, etc. 4.9.5 Heat-treated parts should not have defects such as cracks, chipping and burns. 202
5 Test methods
5.1 Metrological performance test
5.1.1 Test conditions and rules
QB/T 2087—1995
5.1.1.1 The balance should be placed on a solid and horizontal workbench. 5.1.1.2 The base code (including tolerance code) used in the test shall be a Class 5 (M,) code that complies with the JJG99 verification regulations, and shall be equipped with the same amount of magnetic codes required for the following 1/2 maximum weighing test and maximum weighing test. 5.1.1.3 The specific application of the balance's "error does not exceed the maximum allowable error" in the test operation is: the balance should be able to balance under various loading conditions, or if it is unbalanced, add the maximum tolerance magnetic code in the light plate, and the balance pointer should be able to return to the original balance point or exceed the original balance point. 5.1.1.4 When the balance division number n is not equal to 1000, in addition to the following tests , the load point test (see Table 2) where the maximum allowable error changes should also be tested.
5.1.2 No-load test
5.1.2.1 No-load variability
Place the balance on a solid horizontal workbench, align the sliding weight to zero, adjust the balance nut to make the balance in a balanced state (the pointer is aligned with the center line at this time), press any scale pan lightly to make the balance lose balance, the balance should be able to restore balance after swinging, or if it is unbalanced, its error should comply with the provisions of Article 4.1.1.
Then push and pull the support, weight, and force point knife axially along the support, weight, and knife holder respectively, after pushing and pulling, the balance should be able to swing freely and restore balance, or if it is unbalanced, its error should comply with the provisions of Article 4.1.1. 5.1.2.2 No-load sensitivity
Adjust the balance and place the code equivalent to the absolute value of the maximum allowable no-load error on the left or right pan. At this time, the change in the balance position of the pointer should not be less than 1 scale mark.
5.1.3 Vernier scale weighing error
Align the vernier with the zero position of the scale to balance the balance. Then move the vernier to the maximum measurement value position of the scale and place the code of the corresponding value on the opposite pan. The balance should be able to balance, or if it is unbalanced, its error should comply with the provisions of Article 4.1.1. 5.1.41/2 Maximum weighing test and load test Place a pair of equal weights equivalent to 1/2 of the maximum weighing capacity on two pans. Their placement positions are shown in the code placement diagram. Test one by one. The balance should be able to balance in each test result, or if it is unbalanced, its error should comply with the provisions of Articles 4.1.1 and 4.1.2. 5.1.5 Maximum weighing test
Center error
Cross 2
5.1.5.1 Maximum weighing correctness
Cross 1
R--Radius of the bottom plane of the weighing pan
Code placement diagram
QB/T 2087--1995
Put a pair of equal-weight codes equivalent to the maximum weighing in the center of the two pans, and the balance should be able to balance. If it is unbalanced, its error should comply with the provisions of Article 4.1.1.
5.1.5.2 Maximum weighing sensitivity
Adjust the balance and place the code equivalent to the maximum allowable error absolute value at the maximum weighing in the left or right pan. At this time, the change in the balance position of the pointer should not be less than 1 division. 5.1.6 Maximum safe load bzxz.net
Put 125% of the maximum weight of the scale in each of the two pans, and the balance should be able to swing normally. 5.1.7 Reset empty scale test
Take out all the magnetic codes in the two pans, the balance should be able to restore balance, if it is unbalanced, its error should comply with the provisions of Article 4.1.1. 5.1.8 Repeatability test
Adjust the balance, load the maximum weight on the balance, weigh three times, the difference between the results should comply with the provisions of Article 4.1.4. 5.2 Magnetic code inspection
Carry out verification according to the provisions of JJG99.
5.3 Hardness inspection
Use a hardness tester to test, measure three points evenly at the working part of the part, take the average value, the result or its conversion value should meet the requirements of Article 4.4.
5.4 Surface roughness inspection
Compare and check with sample blocks.
5.5 Parts and assembly inspection
According to the requirements of Articles 4.5 to 4.8, use general measuring instruments, visual light transmission and hand feel to test. 5.6 Appearance
Inspect by visual inspection.
6 Inspection and testing
6.1 The balance and its configuration must be inspected and qualified by the inspection department of the manufacturer or the national metrology and testing department, and obtain a certificate of qualification before they can be released.
6.2 Factory inspection shall be carried out in accordance with the provisions of 4.1.1~~4.1.3, 4.3, 4.8~4.9 of this standard, and each unit shall be inspected. 6.3 In any of the following situations, sampling shall be carried out for type testing in accordance with the provisions of 4.1~4.9 of this standard. a.
New products or old products that have been converted to production; when there are major changes in design, process or materials that may affect product performance, when the product is discontinued for one year and then produced again, the batch-produced products shall be inspected at least once within two years; d.
When the national quality supervision agency conducts quality supervision inspection or quality certification. 6.4 Samples are generally taken from a batch of no less than 100 units. Three units are randomly selected. 1
Marking, packaging, transportation, storage
7.1 Product nameplate marking
Each balance should have a product nameplate fixed in a conspicuous position, and the nameplate should have the following markings: 7.1. 14
Manufacturer name;
Product name, model, and specifications:
Main technical parameters and accuracy level;
Factory number and date of manufacture;
Manufacturing license mark and certificate number.
7.1.2The magnetic code box should have the following markings:
Code level;
Weighing range;
Manufacturer name;
Manufacturing license mark and certificate number.
7.2 Product Packaging
QB/T 2087—1995
Each balance should be packed into a paper box with the knife holder, weight holder, support and knife separated and fixed, and several balances should be packed into an outer packing box together with the matching code.
7.2.2 Packaging Marks
7.2. 2. 1
The following marks should be printed on the balance packaging box: manufacturer's name;
product name, model, specification;
main technical parameters,
manufacturing license mark and certificate number.
The following marks should be printed on the outer packaging box of the balance: manufacturer's name;
manufacturing license mark and certificate number,
product name, model, specifications;
quantity;
weight (gross weight),
volume;
"Handle with care", "Avoid moisture", "Upward" and other words and corresponding pictorial marks, which should comply with GB191; publication date.
During transportation, it is strictly forbidden to drench, invert, press, roll over and drop the balance. 7.4 Storage
The balance must be stored in a dry, well-ventilated room without corrosive gases. The storage period shall not exceed 6 months. Additional remarks:
This standard was proposed by the Quality Standards Department of China Light Industry Association. This standard is under the jurisdiction of the National Weighing Instrument Standardization Center. This standard was drafted by Changshu Weighing Instrument Factory. The main drafters of this standard are Xiong Xiqi and Lu Hongxiang. 205
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