The universal coupling makes use of the characteristics of its mechanism, so that the two shafts are not on the same axis, and can realize continuous rotation of the two connected shafts when there is an angle between the axes, and reliably transmit torque and motion. The biggest characteristics of universal coupling are: its structure has greater angular compensation capacity, compact structure and high transmission efficiency. The included angle of two axes of universal couplings of different structural types is different, generally between 5 ° and 45 °.

catalogue

1 Structural type

▪ purpose

▪ National standard specification

2 Classification

▪ function

▪ type

3 Selection

4 Selection calculation

5 Deviation knowledge

6 Materials

7 Relevant parameters

8 Selection

9 Alignment process

10 Measurement sequence

Structural type editing and broadcasting

Universal coupling

Universal coupling

Universal couplings have a variety of structural types, such as: cross shaft type, ball cage type, ball fork type, bump type, ball pin type, ball hinge type, ball hinge plunger type, three pin type, three fork rod type, three ball pin type, hinge rod type, etc; The most commonly used is the cross shaft type, followed by the cage type. In practical application, it can be divided into heavy duty, medium duty, light duty and small duty according to the torque transmitted. [1]

purpose

A mechanical part used to connect two shafts (driving shaft and driven shaft) in different mechanisms and make them rotate together to transmit torque. In the high speed and heavy load power transmission, some couplings also have the functions of buffering, damping and improving the dynamic performance of the shafting. The coupling is composed of two halves, which are connected with the driving shaft and driven shaft respectively. Generally, power machines are connected with the working machine by means of couplings. [1]

National standard specification

The cross axle type universal coupling is a universal coupling with a large amount of usage, and the bearing is a wearing part of the cross axle type universal coupling. The main difference of several large cross type universal couplings lies in the change of bearing pedestal and cross head, forming different structural forms. In order to ensure the synchronism of the driving and driven shafts, the double connection is adopted in practical applications. The double connection is no more than welding or flange plate connection through bolts. The change of the middle length can take many forms. Cross head components of cross shaft universal coupling are in the following forms: SWC type integral fork head cross shaft universal coupling (JB/T 5513-2006), SWP type partial bearing seat cross shaft universal coupling (JB/T 3241-2005), SWZ type integral bearing seat cross shaft universal coupling (JB/T 3242-1993), WS type small double cross shaft universal coupling (JB/T 5901-1991), WSD type small single cross shaft universal coupling (JB/T 5901-1991) Cross wrap for SWP type cross shaft universal coupling (JB/T 7341.1-2005), and cross wrap for WGC type cross shaft universal coupling (JB/T 7341.2-2006). The above heavy and small cross type universal couplings are all universal. Different models in the automotive industry have their own special cross type universal couplings or other types of universal couplings. For example, the car selects the ball cage universal coupling. In addition, agricultural machinery, industrial machinery and other sports machinery products also have special universal couplings, most of which are cross shaft universal couplings. 

Classified editing and broadcasting

There are many kinds of couplings, which can be divided into: ① Fixed coupling according to the relative position and position change of the two shafts to be connected. It is mainly used in the place where the two shafts are strictly aligned and no relative displacement occurs in the work. The structure is generally simple, easy to manufacture, and the instantaneous speed of the two shafts is the same. It mainly includes flange coupling, sleeve coupling, clamp coupling, etc. ② Movable coupling. It is mainly used in the place where the two shafts are deflected or have relative displacement during work. It can be divided into rigid movable coupling and elastic movable coupling according to the method of displacement compensation. Rigid movable coupling compensates by using the mobility of the dynamic connection formed between the working parts of the coupling in a certain direction or several directions, such as tooth embedded coupling (axial displacement is allowed), cross groove coupling (used to connect two shafts with parallel displacement or small angular displacement), universal coupling (used for places with large deflection angle of two shafts or large angular displacement in work), gear coupling (comprehensive displacement is allowed) Chain coupling (radial displacement is allowed), etc. Elastic movable coupling (elastic coupling for short) compensates the deflection and displacement of two shafts by elastic deformation of elastic elements. At the same time, elastic elements also have cushioning and damping properties, such as serpentine spring coupling, radial multilayer leaf spring coupling, elastic ring pin coupling, nylon pin coupling, rubber sleeve coupling, etc. Some couplings have been standardized. During the selection, the appropriate type shall be selected according to the work requirements, then the torque and speed shall be calculated according to the shaft diameter, then the applicable model shall be found out from the relevant manual, and finally the necessary checking calculation shall be made for some key parts. 

function

It is used to connect the two shafts together. When the machine is running, the two shafts cannot be separated. The two shafts can only be separated after the machine is stopped and the connection is disassembled. 

type

Due to manufacturing and installation errors, deformation after loading, and the impact of temperature changes, the two shafts connected by the coupling will cause changes in the relative positions of the two shafts, which often cannot ensure strict alignment. According to whether the coupling has elastic elements, whether it can compensate various relative displacements, that is, whether it can maintain the connection function under the condition of relative displacement and the purpose of the coupling, the coupling can be divided into rigid coupling, flexible coupling and safety coupling. The main types, characteristics and functions of couplings in the transmission system Remarks Rigid couplings can only transmit motion and torque, and do not have other functions. Flexible couplings without elastic elements, such as flange couplings, sleeve couplings, and jacketed couplings, can not only transmit motion and torque, but also have varying degrees of axial, radial, and angular compensation performance, including gear couplings, universal couplings Flexible couplings with elastic elements such as chain coupling, sliding block coupling and diaphragm coupling can transmit motion and torque; With varying degrees of axial, radial and angular compensation performance; It also has the functions of vibration reduction and buffering to varying degrees. It can improve the working performance of the transmission system, including various non-metallic elastic element flexible couplings and metal elastic element flexible couplings. The structures of various elastic couplings are different, with large differences. Their functions in the transmission system are also different. The safety couplings transmit movement and torque, and overload safety protection. Flexible safety couplings also have different degrees of compensation performance, including pin type, friction type, magnetic particle type, centrifugal type, hydraulic type and other safety couplings 

Select Edit Broadcast

The selection of coupling mainly considers the speed of the required transmission shaft, the size of the load, the installation accuracy of the two connected parts, the stability of rotation, the price, etc., and selects a suitable coupling type by referring to the characteristics of various couplings.

The following points can be considered in specific selection: most couplings have been standardized or normalized. The designer's task is selection, not design. The basic steps for selecting the coupling are as follows: Select the type of coupling according to the size of the transmitted load, the speed of the shaft, the installation accuracy of the two connected parts, etc., and refer to the characteristics of various couplings to select a suitable coupling type. 1) The size and nature of the torque to be transmitted and the requirements for the damping function. For example, the gear coupling can be selected for high-power heavy load transmission; For transmission with severe impact load or requiring elimination of torsional vibration of shafting, coupling with high elasticity such as tyre coupling can be selected. 2) The working speed of the coupling and the centrifugal force caused. For high-speed transmission shafts, couplings with high balance accuracy, such as diaphragm couplings, should be selected, rather than eccentric slider couplings. 3) The magnitude and direction of the relative displacement of the two axes. When it is difficult to maintain the strict and accurate alignment of the two shafts after installation and adjustment, or the two shafts will produce large additional relative displacement during the working process, the flexible coupling shall be selected. For example, when the radial displacement is large, sliding block coupling can be selected, and universal coupling can be selected for the connection of large angular displacement or intersecting two shafts. 4) Reliability and working environment of coupling. Generally, the coupling without lubrication made of metal components is more reliable; The performance of couplings requiring lubrication is easily affected by the degree of lubrication perfection and may pollute the environment. Couplings containing non-metallic components such as rubber are sensitive to temperature, corrosive media and strong light, and are prone to aging. 5) Due to manufacturing, installation, load deformation and temperature change, it is difficult to maintain strict and accurate alignment of the two shafts after installation and adjustment. There is a certain degree of x and Y direction displacement and deflection angle CI. When the radial displacement is large, sliding block coupling can be selected, and universal coupling can be selected for the connection of larger angular displacement or intersecting two shafts. When the two shafts produce large additional relative displacement in the working process, the flexible coupling shall be selected. [1]

Select calculation, edit and broadcast

Calculated torque of universal coupling: [1]

Tc=TKnKhK Ka≤Tn(N·m)

Under alternating load: Tc ≤ Tf (N · m)

Where, Tn -- nominal torque of universal coupling, N · m, (it is the theoretical calculation value under given conditions, i.e. coupling speed, n ≈ 10r/min. Bearing life Ln=5000h, axis angle=3 °, and the value when the load is stable);

Tf -- fatigue torque of universal coupling, N · m

T -- theoretical torque of universal coupling, N · m; Where, T=9550Pw/N (N · m)

Pw -- driving power, kw

N - rotational speed of universal coupling, r/min

Universal coupling

Universal coupling

Kn -- speed correction coefficient of universal coupling, Kh -- bearing life correction coefficient of universal coupling

K -- Correction coefficient of angle of two axes of universal coupling

Ka -- load correction factor. Ka=1.0 when the load is uniform and the work is stable; Ka=1.1~1.3 under uneven load and moderate impact; Ka=1.3~1.5 for large impact load and frequent forward and reverse rotation, Ka>1.5 for large impact load and frequent forward and reverse rotation.

For the universal coupling with high speed, large angle or its length exceeding the specified value, in addition to the above calculation, its rotation flexibility must also be checked. The rotation flexibility is expressed in n, generally: n>18000.

Where - axis angle of universal coupling, (°); N - rotational speed of universal coupling, r/min

Deviation knowledge editing and broadcasting

Universal coupling is widely used in all kinds of general machinery because of its large deviation angle and high transmission torque Common types of universal couplings include universal type, high speed type, miniature, retractable, high torque universal couplings, etc WSD small cross universal coupling is suitable for connecting the included angle of two shaft axes β ≤ 45 ° transmission shafting; Single cross universal coupling and double cross universal coupling transmitting nominal torque of 11.2~1120N · m Universal coupling is applicable to the included angle of two axes on the same plane of the connection space β For transmission occasions ≤ 45o, the transmitted nominal torque is 11.2-1120N. m. WSD type is single cross universal coupling, and WS type is double cross universal coupling. The maximum included angle between shafts of each joint is 45o. Finished hole H7 can be provided with keyway, hexagonal hole and square hole as required. The included angle between two shafts is allowed to change with the work needs within the limited range [1]

Material editing and broadcasting

No. 45 steel, No. 45 forged steel, 40 chromium, cast iron. [1]

Relevant parameter editing and broadcasting

SWC type - Cross bearing parameters matched with universal coupling [1]

Coupling specification

φ M(mm)

H(mm)

SWC160

sixty-five

one hundred and thirty-six

SWC180

seventy-two

one hundred and fifty-four

SWC200

eighty-two

one hundred and seventy-one

SWC225

ninety

one hundred and ninety-two

SWC250

one hundred

two hundred and fourteen

SWC265

one hundred and eight

two hundred and twenty-six

SWC285

one hundred and fifteen

two hundred and forty-three

SWC315

one hundred and thirty

two hundred and sixty-nine

SWC350

one hundred and forty-five

two hundred and ninety-nine

SWC390

one hundred and sixty-five

three hundred and thirty-three

SWC440

one hundred and eighty-five

three hundred and seventy-seven

SWC490

two hundred and ten

four hundred and nineteen

Editing and broadcasting of lectotype problems

Prerequisites and conditions must be specified before the type selection of universal coupling: 1. Whether there is a transmission device between the prime mover and the universal coupling. If there is any transmission ratio, several shafts will output after passing through the intermediate transmission device, that is, whether there is power split. Consider the type, power and speed of the prime mover. 2. It is necessary to consider the type of prime mover and the load category of load transmitted by the optional cross universal coupling: one-way constant load, pulsating load or two-way alternating load. What is the installation status of universal coupling. Horizontal, vertical or inclined installation. The axis angle shall be less than 3 degrees as far as possible. If it must be installed obliquely, the horizontal and vertical angles shall be determined. 3. Considering the working environment of the prime mover and whether there is the influence of high temperature, dust, water spray, chemical corrosion and other harsh environmental conditions, the corresponding type of universal coupling shall be selected according to the different operating environment. 4. It is necessary to know the connection form and specific installation dimensions required at both ends of the universal coupling, and whether there are special requirements such as installation brackets. 5. What is the rotational speed of the cross universal coupling itself. Whether dynamic balancing is required. Dynamic balance or balance is required, and which level of balance quality is required. 6. Whether the installation position is limited. What is the specific installation length and whether expansion is required. When expansion is required, what is the outward elongation of the universal coupling in the shortest state. For universal couplings that do not need expansion and contraction, the compensation of axial dimension error must be considered, and the position for compensation in the system shall be determined. Through the understanding of the above prerequisites, gradually determine the specifications of the cardan shaft, and finally determine which structure to choose. The structural forms of universal couplings include cross shaft type, ball cage type, ball fork type, bump type, ball pin type, ball hinge type, ball hinge plunger type, three pin type, three fork rod type, three ball pin type, hinge rod type, etc. The most commonly used type is cross shaft type, followed by ball cage type. In practical applications, the universal couplings are classified into heavy, medium, light and small based on the size of the torque transmitted. If you want to select a coupling suitable for prime mover from so many universal couplings, you need to deeply understand the prerequisites and external influencing factors mentioned above. 

Correction process editing broadcast

The alignment of the universal coupling is one of the important tasks for machine installation. The purpose of alignment is to make the center lines of the driving shaft and the driven shaft on the same straight line when the machine is working. The accuracy of alignment is related to whether the machine can operate normally, especially for high-speed machines It is difficult to achieve the absolutely accurate alignment of the two shafts of the cross universal coupling, and it is even more difficult to maintain the accurate alignment of the continuously running machine The uneven thermal expansion of various parts of the universal cross coupling, the deflection of the shaft, the uneven wear of the bearing, the displacement generated by the machine and the uneven sinking of the foundation are all the reasons why it is difficult to maintain the shaft alignment Therefore, when designing the machine, it is specified that there is an allowable deviation between the centers of the two shafts, which is also required when installing the coupling From the perspective of assembly, as long as the coupling can transmit torque safely and reliably, the larger the allowable deviation of the two shaft centers, the easier it is to meet the requirements during installation. However, from the perspective of installation quality, the smaller the deviation between the center lines of the two shafts, the more accurate the alignment, the better the operation of the machine, and the longer the service life. Therefore, the allowable deviation of the alignment of the two shafts during the installation of the universal coupling cannot be regarded as the margin left by the installer for hasty construction. [1]

Measurement sequence editing