(1) The purpose of preloading
Preloading improves the reliability of the bolted connection, the ability to resist loosening and the fatigue strength of the bolt, and enhances the tightness and rigidity of the joint. A large number of tests and experience have proved that a higher pre-tightening force is beneficial to the reliability of the connection and the service life of the connected parts, especially for the connection with sealing performance requirements. However, if the pre-tightening force is too high, if the control is improper or accidentally overloaded, the connection will fail.
(2) Determination of pre-tightening force Q p
The bolt-and-nut connection of the common structure is due to two kinds of stresses due to the tightening force of the bolt and the torsional shear stress caused by the threading moment. Therefore, the pre-tightening force for tightening the nut to break the bolt is generally controlled to be less than 80% of the tensile force that causes the bolt to simply break and break.
In order to give full play to the potential of bolting and to ensure the reliability of the joint, the pre-tightening stress Qp of the bolt should be higher than 0.8Qs, where Qs is the yield limit of the bolt material (ie the value of the yield point). .
In general machinery, Qp = (0.5 ~ 0.7) Qs
In aerospace machinery, Qp≈0.35Qs
In special connections such as high-strength bolt friction connections, Qp≈0.75Qs
The pre-tightening index should be determined by considering whether it is a tensioned bolt or a sheared bolt, whether the bolt is subjected to a variable load, whether there is a seal requirement for the connection, and how accurate the installation tool and method are. Whether the connection location is convenient for installation, etc.
In general, the pre-tightening force used for steel bolts can also be considered in the above factors.
For important bolting connections, pre-tightening or tightening torque indicators should be indicated in the product assembly drawing, and strict control should be taken during installation.
(three) tightening torque
When tightening the bolt connection, the tightening torque T generally needs to overcome the frictional moment between the nut and the connected part of the joint or the washer (about 5% of the tightening torque) and the frictional torque of the thread pair (about 40% of the tightening torque). Due to the force of the threaded bevel, the resistance torque (about 10% of the tightening torque) is generated, and the connecting member generates the pre-tightening force Qp. For bolts with a nominal diameter of d (mm), the relationship between T(N.mm) and Qp(N):
T=k*Qp*d
Where: k——tightening torque coefficient
For coarse steel bolts of M10~M68, when the thread is not lubricated, the rough formula is:
T=0.2 Qp*d
(4) Examples of control methods for preloading force:
Torque method: generally use a pointer type torque wrench (force torque wrench) or preset type torque wrench (fixed torque wrench). The control preload is achieved by controlling the tightening torque. The torque method is a widely used method at home and abroad. Its shortcoming is that it is simple and simple, easy to implement, does not require complicated equipment and cost, but the measured pre-tightening force error is large, and the general error is ±25%. This is mainly due to the difference in surface quality (including roughness, thread accuracy, lubrication, plating, etc.) and tightening speed of the connector and the connected member.
Characteristics and Advantages
(1) Intelligent control design: adjustable main parameter and secondary parameter automatically according to the weight of door leaves;
(2) Low noise: Special static sound track, integration of motor, worm-gear and retarder.
(3) Anti-clamping function: automatically reverse when meeting barriers;
(4) Unique electronic motor lock: the motor will lock up when the door is forced to open.(controlled by remote or switch)
(5) Tighten force: seal door when closed, power consumption approximately 10W under standby;
(6) Advanced brushless motor(36V,100W) can automatically adopt different heavy door leaves;
(7) Bi-doors inter-locking: one of the door leaves always remains closing;
(8)Safety sensor terminal: sensor stops working when door closed;
(9)Unique coating technology: never rusty;
(10)Easy and convenient to install;
(11)Working Process: when the door leaf closes to the right place, the door leaf will slightly shift to the door frame and the ground. The rubbers on the four sides of the door leaf will completely combine with door frame and ground, which ensures air tightness. When the door is open, the rubbers will separate from door frame and ground, which avoids contraction on the ground.
Technical Specification
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Specification |
Light Duty |
Heavy Duty |
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Rang of the Door |
Single-Leaf |
Double-Leaf |
Single-Leaf |
Double-Leaf |
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Door leaf max weight |
100kg |
100kg x 2 |
200kg |
200kg x 2 |
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Mounting Method |
Surface mounting or built-in mounting |
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Open Width |
700-2000mm |
650-2000mm |
750-2000mm |
650-2000mm |
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Power Supply |
AC 220v ± 10%, 50-60 Hz |
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Opening Speed |
300-500mm/s (adjustable) |
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Closing Speed |
250-550mm/s (adjustable) |
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Creep speed |
30-100mm/s (adjustable) |
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Hold-open time |
0.5-20s (adjustable) |
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Airproof Force (Max.) |
>70N |
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Manual Pushing Force |
<100N |
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Electronic Lock Force |
>800N |
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Power consumption |
150W |
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Ambient temperature |
-20+50 C |
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Technical Details:
(1) Rubber lining sealing technology combined with V groove on the guide rail enables the door completely sealed when the door closed;
(2)Special door body location technology. Semicircular surface beam on the ground matches with the V style groove at the bottom of door leaf, which stop the door from swing and make sure it moves stable and smooth;
(3) The door body decorated with matte stainless steel or spray surface, and on the middle and both sides with sealing stripes to ensure the hermetic effect.
(4)Feet sensor switch applied to avoid contagion;
Stainless Steel Sliding Door,Stainless Steel Bypass Sliding Door,Stainless Steel Interior Sliding Door,Stainless Steel Folding Sliding Door
Shenzhen Hongfa Automatic Door Co., Ltd. , https://www.hfhighspeeddoor.com