Bolt Joint For Engine & Apply Technology For Screw Tool

IntroductionThe purpose of the screwing is producing and keeping a certain of pressure between the joining parts.In this paper,I give a particular description of the screwimg by analying its character.According to different type of connection ,1 bring forward relevant screw down and inspecting control method.Beside that,it also includes the description of screw tool and checkout method ,which forming a integrated screwing and control system.1.Information related to screw downIn this paper I have made a particular description of the information related to screwing.1.1 Screw-down process:Picture 1 show the relation between the screw-down pressure and the rotation of bolt.At the beginning the bolt can be turned with little moment without pressure.When it reach the combination surface,the screw-down process start exactly as well as the produce of pressure increasing with the rotation.1.2 Hard connection and soft connectionScrewing can be hard or soft even between them.Hardness means that we can turn the bolt with little moment before reaching the connection surface.When the bolt gets to the connection surface,we will obtain the demanded torque and pressure only requiring a small rotation(usually not exceeding 30 degree). Softness means that we need more rotation to obtain the demanded torque(usually exceeding 720 degree) after reaching the connection surface.1.3 Torque rateThe torque rate be defined as a ratio between the increment of torque and rotation.Formula for torque rate: R: Torque rate Increment of torque : Increment of rotation1.4 Torque distributionAbout 50% torque use for overcoming the friction between the bolt head or nut and the connected surface, about 40% for overcoming the friction occuring between the screw thread, and only 10% transforming into pressure.1.5 Screwing stress As a perfect screwing design the connected point of thread always be the feeblestsection.However the whole screwing will be stable if it still keep integrated. We can also decrease the bolt's number as far as enhancing the screwing stress.1.6 Relation between torque and pressureFormula for this relation:thread anglefor metric thread above formula can be transformed like this:According to mentioned above,it can also be transformed:1.7 Friction and torque influence on presureThere are two main factors have influence on presure : Torque T and friction modulus 2. influence of jolned-parts gasket on screw-downThe influence of joined-parts gasket on screw-down of bolt is complicated.There are some familiar situation , for exemaple short pressed part,long pressed part,long pressed part including elastic component,and the mixture of these situation.3.Control method of screw-downThe puepose of control is to obtain demanded pressure in the screwing by appropriate control method.Because there is no facility menthod to measure the pressure on the assembly line,we have to achieve this indirectly.In this paper, I have introduced 5 different kind of control menthod for screw-down.3.1 Torque control methodTorque control method base on the theory that the pressure and the torque be in direct ratio in the connection.Because the ratio modulus lie on the friction of connecton surfaces and screwing,and the 90% torque use for overcoming the friction,so the change of friction will play a important part in obtainning pressure.3.2 Angle/torque control methodAngle/torque control method base on the theory that the produce of the pressure due to the rotation which elongate the bolt and the joined-parts are compressed.3.3 Bending point control methodBending point control method which make use of the material's bend limit have high precision.The control method be carried out via calculating and judgement the slope of the torque-angle curve continually .3.4 Setting point \angle control methodSetting point \angle .control method be formed based on the angle/torque control method3.5 Sound wave control methodVia measuring the increase of length to identify whether the bolt have reached the bending point.4.Control method monitoringMonitoring is a passive sec...