The Development And Application Of Thread Rolling Machining Technology
In the development and application of thread rolling machining technology, the advantages of high machining accuracy, stable quality, and high production efficiency of this technology are used in the development and application. It is considered to have high reliability in special wire machining equipment. The internal motor high-power operation makes the threaded member Play a connecting role in mechanical properties.
The current thread rolling technology is in urgent need of improvement. The relevant machining faults encountered in the production site are demonstrated, the causes are analyzed, and effective improvement measures are proposed.
In order to improve the performance and accuracy of the screw parts of the thread rolling machine, non-standard super-long screws are generally used for assembly in the state of the stator and rotor cores of the motor for commutator, Huahuan assembly, DC motor assembly, and so on. Compared with ordinary bolts, these threaded parts have the characteristics of high strength, good material and large mechanical properties. In the process of using thread rolling machine, the application of new methods and new processes is constantly explored to promote the adaptability of thread rolling machine Product diversity needs.
1 Thread rolling machine tool machining method
Thread rolling machine machining adopts one-time rolling forming method, which is easy to operate, safe and reliable. Under the thread standard setting, the diameter of the steel bar can be adjusted according to the design requirements, and the length of the thread can meet the needs of the machine tool machining method. It is processed by the thread rolling machine method of one-time roll forming. The specifications of the steel bar are threaded. The length of the operation mode of automatic reversing and returning to Lebanon, palace construction and automatic parking, using a coolant device, reliable operation performance, improve work efficiency, turn on the switch in turn, can continuously process a large amount of silk.
The thread rolling machine is generally used for the production of threaded thread heads for ribbed steel rolls. It can process ribbed steel bars with a diameter of 16 to 40 mm. Automatic opening and closing mechanism, cooling system, control system, etc. The main parameters are the steel straight thread fan machine as an example. It can complete the machining from glass to rolling thread at one time. Its unique tool can automatically open and close, machining The back buckle and thread structure are compact, and it can also be processed with high mechanical strength. The thread size accuracy after machining is high and the tooth shape is full.
Make preparations before machining, and connect the ground wire and power wire as required. The power supply is generally a three-phase 380V, 50Hz AC power supply, with an automatic switch with leakage protection function to protect personal safety. The cooling liquid in the cooling box of the thread rolling machine is tested in an empty car. After the power is turned on, the cooling water pump can be guaranteed to operate normally. The continuous operation of the button has checked whether the electrical control system is normal. The thread rolling machine is adjusted before machining, and the thread rolling wheel adapted to the machining execution is exchanged. Ensure that the power supply is grounded according to the diameter of the processed steel bars, the connectors on the equipment are fixed, the movement is flexible, and the cooling fluid in the cooling box is sufficient. It uses sliding self-centering machining method to process the thread head, and completes the screw machining at a speed of 50 revolutions per minute. The roller head rotates and moves axially. The operator operates the handle, and the rack drives the reducer and the glass rolling stones to move along the slide bar to complete. After the thread rolling machine installs and forms the thread, it uses the active motor to control the advance and retreat of the knife, and the rotation of the motor drives the deceleration operator to move the handle to give it. During thread machining, the trigger switch touch plate retreats in the reverse direction, and it stops automatically when it reaches the starting position.
2 Failures and causes of thread rolling machining
2.1 Long thread rolling failures are prone to failures that are different from ordinary screws.
For example, during the installation process, it was found that the long thread could be up to 560 mm long, and the thread was randomly buckled after rolling. During the thread rolling process, because the center of gravity is close to the position of the thread rolling and the machine pallet, there is a problem with the positioning of the thread rolling machine pallet parallel to the axis of the thread rolling wheel, which leads to the rolling of the middle and long screw of the thread rolling and the occurrence of centrifugation. In the remote situation, even though the manual auxiliary correction method is adopted, the normal thread level cannot be guaranteed. This is due to the instability of artificially made parts that do not meet the design standards. During the rotation, problems such as non-parallel and axis offset of the rolling wheel appeared, which failed to meet the design requirements.
2.2 Short thread rolling failure is when the artificial wheel rotates, the part is subjected to artificial external force during the rolling process, which causes the distance. Where the distance between Schlumn end faces is less than 5 mm, it penetrates into smaller parts. In the middle of the rolling wheel near the thread, if the operator does not release the finger in time, the finger will be squeezed.
2.3 The rolling of high-strength threads will cause end-face breakage and the problems of mid-run.
After high-strength heat treatment, under reliability design, there will also be machining differences with rolled workpieces, cross-sections, and chamfers. For example, the axial component of the force is bent, the root of the tooth shape is brittle fracture, and the shear force generated by the bending is greater than the strength limit of the material, which leads to problems such as Mercedes-Benz exercise/expansion. The above reasons are related to the structure of Ross Roshan itself. The shear rate is greater than the thread rolling, the material strength is limited, there is a radius arc between the square heads of the metal fluidity bolt, and the deep tooth shape is the first problem. Into the threaded tooth shape, the force on both sides is uneven, causing the outward force to be greater than the inward force, causing the section to collapse.
3 Solution measures taken by thread rolling machine machining
3.1 To solve the problem of long thread rolling, adjust the horizontal position to the left and right, and fix the side plate screws by fixing the bottom plate and the side plate. Welding on the front baffle of the thread rolling machine can also be adjusted by screw fixing on the trailer barrel to achieve the up and down adjustment of the support height. Through the tension and compression of the spring, hold the handle with one hand to achieve the full support The purpose is to fix the bracket bottom plate on the trailer barrel with one hand, and turn the processed workpiece and the bearing back to the deformable bearing. The operator plays the role of tightening. The hand screw replaces the bearing. After the operation is completed, remove the processed workpiece and install the new workpiece to be processed.
3.2 When rolling a short thread, pay attention to the small screw, the position of the small extension, hold the sleeve with one hand and add the bow and arrow, then loosen the handle, and lock the spring compression force through the piston and the handle. To achieve the purpose of clamping. Hold the sleeve tightly to roll the small street lamp. From the tight position of the small thread, remove and install a new workpiece.
3.3 In response to accidents caused by the rolling of high-strength bolts, the service life of the rolling wheel must be prolonged, and the section of the rough tube must not collapse. To meet the requirements of the end face and chamfer size of the part, optimize the process route, carry out the heat treatment of thread rolling adjustment, increase the undercut groove at the end of the thread, increase the length of the rolling wheel to the foot, and ensure that the blank can also be reduced. The arc radius is controlled by the heat treatment process to improve the rolling process conditions, so that the rail pressure reaches the appropriate size and meets the product quality standards [.
4 Thread rolling machine stiffness characteristic analysis and experimental verification analysis
The method of stiffness characteristic analysis and experimental model verification is used to conduct regular tests on the axial load thread, contact angle and number of rollers. The conclusion drawn is that under the same load condition, the contact angle, the number of rollers, and the height of the circumference will increase accordingly, and it is suitable for multi-point contact between the parts of the traditional structure and the transmission of force. Test. Perform experiments on nonlinear stiffness, establish an accurate stiffness model, perform modeling, and use dynamic analysis to obtain data on load-bearing capacity, friction mechanism, and efficiency calculations. Firstly, a motion model is established. A nut that revolves around the screw axis and moves linearly along the axis is demonstrated on the relationship between the screw rotation angle and the axial displacement, and the stiffness model is established. The simplified model shows that it bears load and high pressure. The rigidity of the column such as stiffness and contact stiffness.
The height of the cylinder has little effect on the entire height model. The height is expressed as a linear stiffness. The main body height is expressed by a formula. The main contact radius of curvature has a greater influence on the contact stiffness. It is necessary to establish a mathematical model of the thread contact surface through differential geometry The form of the curved surface obtains the main curvature radius of the contact surface, and establishes a stiffness model for the overall axial direction, which mainly includes the axial stiffness of the threaded contact part and the axial stiffness of the non-threaded contact part. No-load roller screw axial stiffness, deformation coordination equation conversion. Through the form of characteristic simulation, the parameters that affect the stiffness of the lever shaft are obtained. For rollers with eccentricity, the ideal state is obtained according to the setting around the circular distribution of the thread. The existence of the eccentricity will affect the size of the thread. Experiments show that when the contact position is biased to the outside, the gap between the two wheels is positive , The loading device will produce pressure deformation of the thread. From the results, it can be seen that the number of rollers has a greater impact on the stiffness when the load is large. By comparing the results of the screw axial stiffness experiment and the axial steel model, no matter the impact of the thread stiffness of the part we touch, under the condition of increased load, when the load reaches a certain level, the axial stiffness tends to a maximum Value, so that the process operation can produce the best machining effect under a reasonable design.
The thread rolling machine needs to rise slowly when pressurizing, and the oil pressure remains stable during work to prevent the impact of the external environment. The vibration of the machine tool is small when it is running, and the rolling thread will not be in an impact working state. The operation of increasing the chamfering length of the four-wheel roll is carried out close to the hexagonal end surface, which effectively reduces the occurrence of section failure. The end has passed the analysis of the typical workpiece machining process during the use of the thread rolling machine, and proposed corresponding improvement measures from the aspects of technology, flow, process, product structure, etc., which can further improve the function of the thread rolling machine and make its machining range more Extensive.
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