MJ internal thread rolling strengthening device and strengthening method

Abstract

The invention discloses a MJ internal thread rolling strengthening device and a strengthening method. The device comprises a cutter bar, a rolling mechanism and a pressure conducting mechanism; the lower surface of the cutter bar along the length direction is successively provided with a first groove, a second groove and a through hole, the rolling mechanism is placed in the through hole and can move up and down, the pressure conducting mechanism comprises a force transmitting part, a spring and a pressure sensor, the cutter bar is arranged horizontally, the spring and the pressure sensor areplaced in the first groove from top to bottom, the pressure sensor moves up and down and compresses the spring; and the force transmitting part comprises a mounting part and a first arm and a second arm which are symmetrically connected to both ends of the mounting part along the length direction of the cutter rod, the mounting part is installed in the second groove, the first arm is butted with the bottom part of the pressure sensor, and the second arm is butted with the bottom part of the rolling mechanism. According to the MJ internal thread rolling strengthening device and the strengthening method, the symmetrically arranged force transmitting part can realize the equal pressure transmission between the rolling mechanism and the pressure sensor; and because displaying and controlling rolling pressure with high precision are directly carried out, the consistency of rolling strengthening effect and the rolling precision are greatly improved.

Description

technical field [0001] The invention relates to the technical field of metal material surface strengthening, in particular to an MJ internal thread rolling strengthening device and strengthening method. Background technique [0002] Thread rolling strengthening is to use the elastic-plastic deformation properties of steel, use a roller that matches the shape and geometric dimensions of the fillet at the root of the thread, and apply a certain rolling force to the fillet at the root of the thread when the part rotates. A method of strengthening threads by producing an elastic-plastic deformation layer on the metal surface. The thread rolling strengthening process is often used in the manufacturing process of aerospace high-strength metal parts with MJ threads (reinforced threads). It is controlled as a special process. This process combines the structural characteristics of MJ threads to significantly improve the fatigue life of parts. [0003] During the rolling strengtheni...

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Problems solved by technology

At present, there are two main rolling methods used in MJ thread rolling strengthening: one is to use the radial feed rate of the machine tool as the main process parameter for indirect control, and different feed rates represent different rolling forces. Due to the different elastic modulus of different materials, the different rigidity of the system composed of "parts-rolling tools" and the different observations of "zero position" by different operators when setting the tool, the same feed rate can be used for different materials or different parts. The rounded corners of the thread root are rolled and strengthened, and the actual rolling force may vary greatly, resulting in a large difference in the strengthening effect, and the consistency of the rolling strengthening effect is poor; the second is that the rolling tool comes with a dial, The dial reading indicates the actual radial feed of the roller, and the rolling force value is obtained through the comparison table. This method is greatly improved compared with the first method, and avoids the "machine tool-tool system" rigidity, material elastic modulus, part structure or Influenced by human factors and other factors, this method still cannot directly and accurately give the rolling force value, and the rolling force value obtained through the comparison table has a large range, which cannot meet the accuracy requirements of MJ internal thread rolling strengthening and small rolling force

At the same time, the above two methods also have the following common disadvantages: 1) MJ thread rolling reinforcement cannot be carried out on CNC machine tools. Since more and more parts have larger gyration radius, the gyration radius of ordinary machine tools is not large at present. As a result, the rolling strengthening of some parts is limited; 2) The profile of the roller rim cannot adapt to the fillet at the root of the thread. During the rolling process, the roller cannot cause the roller to move along the axial direction of the machine tool according to the variation of the thread pitch within the tolerance range and the accuracy of the machine tool. Automatically adjust the small jump to make the roller align with the rounded corner of the thread root in time, which will cause factors such as machine tool precision and thread processing precision to have a certain impact on the consistency of the rolling strengthening effect; 3) The precision of the parts clamping is high, Generally, the coaxiality is required to be within 0.05mm, but for large complex parts or thin-walled parts, repeated clamping can only meet this requirement, which often takes a lot of time; 4) The precision of tool setting is high, and the roller must be accurately aligned with the fillet at the root of the thread Otherwise, it is easy to roll onto the thread profile surface, especially for internal threads, the rolling tool occupies most of the space, the observation space is small, and the tool setting is difficult

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