GB 12977-1991 Balancing machine protective cover and other safety measures
Some standard content:
National Standard of the People's Republic of China
Balancing machines Enclosures and other safety measures
Balancing machinesEnclosures and other safety measuresGB12977-91
This standard is equivalent to the international standard ISO7475-1984 "Balancing Machine- —Protective covers and other safety measures. Subject content and scope of application
This standard details the requirements for protective covers and other safety measures when designing, manufacturing and using balancing machines, the definitions of different levels of protection, the application limits of each protection level, and stipulates Corresponding protective measures. This standard applies to general safety measures for horizontal, vertical and special balancing machines. This standard does not cover other special properties of protective covers, such as reducing noise, reducing air resistance, vacuuming, etc. 2 Reference standards
GB2298 Mechanical vibration and impact terminology GB6444 Balance vocabulary
3 Possible dangers and preventive measures
3.1 Universal joint disengagement and damage during transmission||tt| |Precautionary measures: Install a protective cover around the universal joint. 3.2 The operator is entangled in the drive belt
Preventive measures: Use a belt cover to cover the motor and tensioning pulley, or use the protective cover of the balancing machine itself. 3.3 Preventive measures for the rotor to axially detach from the support due to excessive axial thrust due to roller support skew or wind force: Belt-driven balancing machines can use axial stop devices. 3.4 Support preventive measures for the rotor to break away from the balancing machine due to excessive initial unbalance or large mass deflection or separation during rotation: when using bearing pad supports, use upper pad compression measures; when using roller supports In this case, use a compression device.
3.5 Preventive measures for operators to come into contact with any part of the rotating rotor (such as blades or other protruding parts): warning barriers, protective railings, protective screens or protective covers can be used to prevent this. 3.6 Preventive measures for welding debris, bolts, keys or calibration quality that fly out from the rotor: Wear protective glasses or protective masks for small rotors, and use protective covers for larger rotors. 3.7 Precautions against parts flying out from the rotating rotor, such as blades; adopt similar measures to those in 3.8. 3.8 Preventive measures for damage to the rotor or main components during high-speed balancing and overspeed tests: It is usually necessary to use explosion-proof protection facilities such as pits; under certain conditions, other safety measures should be taken, such as evacuating the work area.
4 Safety facilities
4.1 The precautions taken in Articles 3.5 to 3.8 of this standard shall be determined by the user according to the different types of rotors they are balancing. Approved by the State Bureau of Technical Supervision on June 6, 1991, 658 | The preventive measures taken in Article 1 may be adopted in accordance with relevant regulations. 4.3 Under the conditions described in Articles 3.6 and 3.7 of this standard, the hazards of flying objects are basically determined by three parameters, namely the mass, speed and impact area of ??the flying objects.
4.3.1 When the quantity and speed of the flying objects are small, wear protective glasses or a protective mask. Note: Test method for protective glasses or protective masks: they should be able to withstand the impact of a steel ball with a diameter of 22mm and a mass of 44g falling from a height of 1.3m. 4.3.2 When half the product of the mass of the flying object and the square of the velocity (m2/2) exceeds 0.56N·m, a protective cover is required. 4.4 Under the circumstances described in Article 3.8 of this standard, the mass and speed of the debris flying off the rotor are generally relatively large, and explosion-proof protective covers or other safety facilities need to be used.
4.5 Figures 1 to 5 of this standard show several types of safety facilities: Figure 1 Typical rotor guard for a horizontal balancing machine used in batch production; b.
C||tt| |d.
e.
Figure 2 Typical rotor protective cover of vertical balancing machine for batch production; Figure 3 Universal retractable complete machine protective cover; Figure 4 with explosion-proof cover pit;
Figure 5 has a simplified version of an explosion-proof door.
Picture
Picture 3
Precise operation
Picture 2
Picture
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5 protection level selection
GB 12977—
91
Figure 5
The user should estimate the rotor, the balancing speed of the rotor (r/min), and the predetermined balancing method to determine the appropriate Security Measures. Five protection levels are given in Table 1, and the applicable limits of each level are given. Table 1 Protection level
Level
c
D
No protection required
Safety hunting
No protection or make-up required on the rotor Other arrangements. The safety protection requirements for driving parts should be in accordance with relevant regulations. Only protective glasses or masks should be used for protection
The safety protection requirements for driving parts should be in accordance with relevant regulations. There is no protection around the workpiece
Fence protection Or use protective glasses and protective masks to protect the safety protection requirements of driving parts. In accordance with relevant regulations, use fences or railings to prevent contact with dangerous surfaces of rotating workpieces
Debris protection
Safety of driving parts Protection requirements should be in accordance with relevant regulations. The debris protection cover should be installed on the part of the workpiece where debris may fly out or on the entire machine to prevent the smallest debris and the debris with the greatest penetration ability from flying from the rotor. Come out and penetrate
Explosion-proof protection
The safety protection requirements of driving parts are in accordance with relevant regulations. The explosion-proof protective cover is installed around the workpiece or the complete machine to prevent the main part of the rotor from penetrating after the entire rotor is destroyed| |tt||Technical requirements for level 6 protection
Level 6.10 protection
a.
b.
660
Hazard assessment||tt| |No obvious danger from the rotor
The maximum equilibrium speed of the rotor used will not cause major damage to the rotor. At this time, the debris intensity coefficient is multiplied by half of the maximum debris mass multiplied by the square of the debris speed, that is: ||tt| |kmu2/2≤0.56 Nm
The maximum balancing speed of the rotor used will not cause major damage to the rotor. At this time, the cme2/2 value of the rotor parts (or unbalance correction mass) that may fly out: ||tt ||kmuz/2≤0. 56 N + m
The maximum balancing speed of the rotor used will not cause major damage to the rotor. At this time, the em2\/2 value of the rotor parts that may fly out: km22/2> 0. 56 N·m
The maximum balanced speed of the rotor used cannot exclude major damage to the rotor, and the protective cover must be designed according to the specific rotor parameters and the characteristics of the debris
The rotor surface must be very smooth so that There will be no danger in contact with the rotor; the correction method should be selected so that debris will not fly out from the rotor, usually using the weight removal method; Standard Search
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GB12977 ..91
℃. The rotor will not be seriously damaged at the selected maximum balancing speed d. The rotor will not jump out from the support of the balancing machine through the measures mentioned in Article 3.4, or the rotational energy of the rotor at the highest balancing speed is so small that there is no danger even if the rotor jumps out of the bearing. E.2A level protection
For very small transfers, the impact energy generated by the flying objects from the rotor is very small. Wearing protective glasses and a protective mask is enough to ensure the safety of the operator, and there is no need to expose Rotor protective cover, but must ensure that the impact energy of the maximum fragment is within the requirements of m2≤0.56N·teach.
Level 6.3B Protection
Any parts or unbalance correction mass flying out of the rotor will not exceed the limits specified by Level A protection. To meet this requirement, the duplication method is usually used.
To prevent the operator from accidentally contacting the rotor, fence-type protection, protective rods, and wire mesh protective covers are generally sufficient to prevent the occurrence of danger.
It is also possible to use a protective device that interlocks the driving part. If the protective device is not closed, the rotor cannot rotate. When the risk of contact is particularly high (for example, balancing a medium or large bladed rotor), a safety interlocking system that protects the stack by slowing down the rotor to near zero is required.
Sometimes only part of the rotor is required Protection, other parts belong to level 0 protection. In this case, it is enough to prevent contact with the dangerous surface of the rotor.
If the operator works inside the protective fence, corresponding safety measures must be taken to ensure the operator's personal safety. 6.Level 4C protection
The part of the rotor where debris may fly out should be completely enclosed. When the balancing machine and rotor enter the closed protective cover, the entrance is also protected; or the operator evacuates the dangerous area, which can also meet the requirements of this level of protection. The shield should protect against the worst-case scenario and should have high penetration resistance. After a protective cover has been impacted, it may no longer be usable until all or part of it is repaired or replaced. If the rotor's protective cover is partial (for example, it is open in the axial direction), the possibility of fragments bouncing out should be considered. If a metal mesh protective cover is used, it should be considered that small fragments will not penetrate through the holes. come out. When selecting a shield to protect against debris, it is necessary to consider both the characteristics of the debris flying from the rotor and the protective capabilities of various types of shields
Users should consider the rotor, balancing speed and imbalance used Calibration methods are used to predict the characteristics of debris that may fly out of the rotor during equilibrium, calculate the worst-case penetration capability of each blade, and select a shield that can withstand the debris attack with the maximum penetration energy. 6.5D protection
This level of protection applies to all rotors that are not obviously classified into level 0, A, and B protection by hand, that is, they are used in situations where major damage to the rotor cannot be ruled out. When major rotor damage occurs, approximately one-third of the entire mass of the braids impacts the shield, which should be able to contain flying debris.
When designing the explosion-proof protective cover, all relevant parameters of the balanced rotor, the specific requirements of the manufacturing and loading and unloading processes must be considered. Due to the large penetration ability of high-speed rotor fragments, the divine strike energy calculation formula for the penetration resistance of a C-level shield cannot be used. Their penetration potential should be calculated based on armor penetration or similar techniques. ? Selection of C-level protection for general-purpose weighing machines
7.1 When the user cannot predict the size and type of the balancing rotor of the balancing machine and whether debris may fly out, the following guidelines can be used to select the appropriate protection parameter withstanding capacity .
Universal balancing machines are mainly used for low-speed balancing. The peripheral speed of a typical rotor is generally 10~30m/s. 7.2 Size of fragments
For a general type of rotor, the maximum initial unbalance of the rotor can be determined, so that the maximum corrected mass that may fly out will not exceed 661
Over: ||tt| |Formula. mi—corrected mass, multi;
m—rotor mass, kg.
7.3 Shape and material of fragments
GB12977-91
m2 7.5 m size
(1)
The shape of the fragments is assumed to be equivalent to Figure 6 Safety The shield penetration resistance test is shown with a standard warhead, and it is also assumed that its tip impacts the shield wall first.
Figure 6
The material of the standard push fragment is steel with a hardness of 4050HRC. When it impacts the protective cover, the fragment itself will not produce obvious deformation. 7.4 Penetrating kinetic energy of fragments
The penetrating kinetic energy of fragments is expressed by formula (2): mw*/2
Where: m-——The mass of the fragment, kg; tangential velocity, m /s, that is, the equilibrium rotation speed (r/min) multiplied by the radius (m) of the debris flying point and then multiplied by 2n/60 - the intensity coefficient, the user must estimate, which depends on the material, hardness, shape and impact area of ??the debris. 7.5 Selection of debris intensity coefficient
7.5.1 Low intensity coefficient does not have 0.3.
Spherical quenched steel or soft materials of any shape, such as soft aluminum, soft copper, solder or plastic fragments should be selected with a low intensity coefficient. 7.5.2 Standard intensity coefficient k1.
2
The fragments made of steel with a hardness of 4050HIRC are equivalent to the standard warheads used in the safety shield penetration resistance test shown in Figure 6, and the standard intensity coefficient is selected. Typical standard pieces are bolts, nuts and washers. 7.5.3 High intensity coefficient k10.
When fragments with sharp corners produce large eyebrow forces at the contact point with the protective cover, select a high intensity coefficient. Note: It is sometimes difficult to accurately estimate the value. In this case, it is recommended to determine it experimentally. 7.6 Protective cover anti-penetration capability PRR
7.6.1 For the mass and speed of typical fragments, it is about 020m/s. If the intensity coefficient k is 1, the PRR value can be found from Table 2A. 7.6.2 If the mass, speed and values ??of the debris are different from the values ??listed in Table 2, formula (3) can be used to calculate the PRR value (condition, the debris speed is within the range of 10~30m/s): ||tt ||PRR =- Kem\ /2
In the formula: PRR--the anti-penetration ability of the protective cover N·m table-intensity coefficient (can be selected from the conditions of ?.5); m maximum estimated mass of fragments , kg;
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(3)
2—Speed ??of fragments, m/s.
GB12977—91
7.6.3 Example of calculation of the protection level required by the fragment mass and speed: when mmax = 0. 02 kg
Wmax 20 m/s||tt| |k-10
is substituted into the calculation formula (3) to get: bzxz.net
PRR= 10 × 0.02 × (20)2/2 = 40 N ·m. From Figure 7, the required mass and velocity are determined From the protection level, it can be concluded that when the PRR is 40, the level of protective cover required is C60. Note: ① A fragment with a mass of 0.02kg and a high intensity coefficient k=10 is equivalent to a standard fragment of 0.2kg. ② For fragments with special shapes, or fragments with speeds outside the range of 10 to 30m/s, the required penetration resistance of the protective cover must be determined through tests. ③ For a balancing machine with variable speed, its maximum balancing speed (r/min) is limited by formula (4>: nmax = (60 max)/(2 πRmax)
where: 2max--in 10~ Within the range of ~30 m/s; Rmax-
-the maximum radius when the debris flies out, m.
600
200
“mN w ,/| |tt||100
0.01
C2
Not available
C6
0.02 0.030.05
7.7 Inspection test of protective cover
m/s
piece compliance force one
C60
C20
Not available
0.1
0.20. 30.5 | | tt | | tt | The weakest point of the shield.
7.7.2 The length and width of the test plate should be equal to 10 times the diameter of the standard warhead, and the support conditions of this test plate should be similar to those of the actual shield.
7.7.3 If the standard warhead used in the penetration resistance test of the safety shield cannot completely penetrate the outer surface of the shield wall at a speed of 20m/s, the shield can be considered suitable. 7.7.4 If the test is carried out. The speed of the fragments is not 20m/s, and the PRR value can be calculated using formula (3). But the speed must be between 10 and 30m/s. 663
Protection level
ch
C2| |tt||C6
C20
C60
C200
C600
C2000
Speed
m/s| |tt||20
20
20
20
20
20
20
Table 2|| tt |
kg
0.01
0.03
0.1
0.3
1
3
10|| tt||Diameter
D
mm
8.6
12.5
18.6
26.8
40.1||tt| |57.8
86.4
Length
L
mm
25.8
37.5
55.8
80.4
120.3
173.4
259.2
Note: 1) When the value calculated using formula (3) exceeds the given PRR value, you can choose a higher 2) Specific energy: the standard warhead energy per square millimeter of impact (projectile tip area). Bullet tip diameter
d
mm
2.9
4.2
6.2
8.9
13.4
19.3
28.8
Specific energy
E/nd/g2)
N*m/mm
0.31
0.44|| tt||0.66
0.96
1.43
2.06
3.07
A first-level protective cover.
3) The PRR value of the protective cover recommended here is only applicable to the range of fragment speed 10~30m/s. Additional notes:
This standard is proposed by the Ministry of Mechanical and Electronics Industry of the People's Republic of China. This standard is under the jurisdiction of the Changchun Testing Machine Research Institute of the Mechanical and Electronic Industry. This standard is drafted by the Changchun Testing Machine Research Institute of the Mechanical and Electronic Industry. The main drafter of this standard is Ge Wansen.
664
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Protective cover
PRR3)
N?m||tt ||2
6
20
60
200
600
2000
The best balancing machine|| tt||Great balance ability
kg
1. 5
8
50
250
1500
8000
50000
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