Design of bolt pre-twisting mold

1 Qinghai Institute of Engineering Machinery Xining 810017 Wang Pengkui prepared for the situation, to be hot on the 60014 up-type friction press. Because the part is a high-strength material, the number of each piece is large, and the die structure should be designed as a pre-stressed die. After years of use, the effect is good and meets the normal needs of production.

1 Analysis of the force state of the combined die structure It is well known that the quality of the die structure is mainly related to the stress state of the core. The tensile stress is brittle fracture, and the maximum shear force promotes plastic fracture. The state of the compressive stress is a safe state. 2 is a pre-stressed die structure, in this state, the ratio is in a relatively safe state.

2 Selection of prestressed die interference and determination of slope When designing the prestressed die, the total diameter ratio is chosen to be between 57 and with sufficient interference to ensure sufficient preload. When the prestressed die is assembled, the amount of interference is proportional to the magnitude of the prestress. Within the allowable range of allowable stress, the greater the interference, the greater the pre-stress. The prestressing ring has a yield of 0.350.60. Considering the need of the assembly process and the ease of demoulding, the die core and the middle sleeve are matched by a 3-cone surface, and the jacket and the middle sleeve are preferably 130-cone.

The concave mold of the top of the head is divided into a laterally splitting concave die between the rod and the head, thereby avoiding stress concentration under a small radius, improving the bearing capacity and service life of the mold, and The manufacture of the mold provides convenience. In the manufacture, the transverse section must be carefully manufactured. Otherwise, the spurs will be formed when the bonding surface is in contact with the bad boring head, which will affect the use of the mold, and it is not conducive to the pre-form forming of the part head.

The heat treatment hardness of the jacket should be controlled at 3842 ft. 0. With such hardness, even under a large axial pressing force, cracking does not occur when the outer casing is pressed.

After the above design, the mold is easy to use and the structure is simple. When the grinding wheel is in contact with the workpiece, it will emit a slight hum. After the start of the contact, the grinding wheel should rise about 5 and then the downward feed back to the cutting position. For the entire rough grinding process, the feed rate per grinding wheel should not exceed 0.005; for fine grinding, the feed rate should be reduced to 0.002, and the grinding wheel must be moved several times in the middle of two feeds. Whenever the machine is parked, the grinding wheel head should be raised at least 0.05 before the grinding wheel comes into contact with the workpiece. This will avoid any effect caused by the oil film stored on the table support surface causing the workpiece to lift.

5. After the sharpening treatment, all debris and other materials should be cleaned from the punch and the die. In particular, it should be noted that all the column lubrication grooves and all the convex and concave models are guaranteed. The cavity is cleaned; the punch and die parts should be dried and demagnetized; the edge of the relief die should be deburred.

Replace all the pilot pin ejector pins and other parts into the punch plate and return the ejector plate to the original position to ensure that all the support screws are in place. If necessary, take out the stripper and place the washer under the head of the stripper. Pay attention to the thickness of the washer under each head. Install the guide plate and the floating floating pin on the die plate and add grease to all the oil cups. Only light oil or light spindle can be used in the guide post and guide sleeve of the rolling bearing

Hole Saw

The hole saw, also known as the hole saw or hole saw, refers to a special circular saw in the processing of circular holes in modern industry or engineering. It is simple and flexible to operate, convenient to carry, safe and widely used. The hole opener (cutter) is installed on the ordinary electric drill, and it is convenient to cut round holes, square holes, triangular holes, straight lines and curves on the plane and sphere of various plates such as copper, iron, stainless steel and plexiglass.