Gansu Dingxi High-strength Screw Co., Ltd. (743000) Ma Qin is in the production of standard tight-fitting parts. Nuts of M 24mm or less are generally formed on the cold heading machine. Nuts of M24mm or larger are usually formed on a hot press or a friction press. Most nuts of M30mm and above are hot forged on the general friction press. The commonly used method is to first pass a section of the blank material into a ball.
1: After the art, the second die forging into a hexagonal shape of the nut blank, and then the machine to add drilling, boring, flat end faces, inverted inner and outer corners, tapping the thread, can be formed into the geometrical requirements of the nut national standard. This article GB/T6170 ~6175-2000 Large-size M42~M60mm nut hot die forging forming in the production practice of mold design, process methods to talk about a little experience for peers.
The process flow of the large-size nut in the friction press h using the hot forging forming process is as follows: cutting (calculated according to the material of the nut blank).
Stomach (2) hit the center hole.
The outer circle of the car (because there are some fine cracks on the outer surface of the hot rolled round steel material, it is necessary to drive 2~3mm to prevent the shape of the forming nut from breaking).
Hot die forging: press ball (all the blanks are heated by high frequency and pressed into balls). Immediately after pressing the ball, hot forging and forming the nut blank on the friction press, according to the above process, the nut blank needs to be set to 1 set. The molds, namely the "pressure ball mold" and the "hexagonal forming mold", achieve the required shape geometry. The design of the mold should be carried out in accordance with the provisions of GET6170 ~ 6175-2000. The formed upsetting ratio is large and difficult to achieve in the process. After the ball is pressed and formed, the nut blank is technically reliable, the product quality is stable, and the production is convenient.
Ff: ball mold 1.M ball upper mold 2. pressure ball lower mold 3. mold sleeve 4. mold box 5. gland 6. top rod 7. lower template pressure ball upper mold, pressure ball lower mold and lower punch material 3Cr2W8V is used, and the hardness after heat M is 43~48HKC. The size of the upper and lower molds of the ball is different according to the size of the nut. The main size of the upper and lower molds is the ball diameter Z). > should be smaller than the shape of the forming nut blank s 2.5mm, in order to smoothly carry out secondary forming. According to experience, the height of the inner round table is 10.512.5mm, :, the upper and lower molds of the pressure ball are not, the design dimensions are shown in Table 1. 1 pressure ball upper mold, pressure ball lower mold design size specifications 2, mold design bookmark2 1. Pressure ball mold design bookmark3 shown as the pressure ball mold structure. Since the round bar material i is a structural drawing of the hexagonal forming die, it is mainly composed of an upper punch, a hexagonal die, a bottom punch, a die sleeve, a mold box and a gland. Only the design of the h punch, the hexagonal die and the bottom punch are described here.
Under-machined: When the person (hot processing) is smaller than the size of the hexagonal die, it is 1mm smaller, so that the bottom punch can flexibly move in the hexagonal model cavity during work, and the upper and lower planes of the nut blank can be substantially free of flash. See Table 3 and for the design geometry of the upper and bottom punches.
The heat treatment hardness is 43-48HRC. The hexagonal geometric size is in accordance with GB/T6170~ theoretically, the closer the nut blank of the designed edge size s die is, the better the smin is, so that the geometrical size required by the national standard can be guaranteed and saved. The consumption of nut blank raw materials maximizes the application potential of the mold. However, in actual production, due to the thermal expansion, friction deformation of the mold during use and the cooling reduction of the nut blank after demolding, it is necessary to control the opposite side dimension s to a minimum range, and there is a certain distance from the objective reality. According to the experience gained in the actual production process, the deformation amount is generally selected as 0.3 grid nut forging and forming, and the opposite edge size is generally no longer subjected to the ray process. Only after the product is formed, the heat treatment, pickling before deming, degreasing and Descaling process. Affected by the above process, some of the thin oxides produced on the surface are washed away, and have little effect on the size s. Therefore, the design size s of the opposite side of the hexagonal mold is larger than the minimum size specified by the national standard. According to the national standard GB6170~61752000, the minimum size of the edge plus the maximum size minus the minimum size of the half, that is, the design geometry of the hexagonal die is shown in Table 2.
Table 2: Six-square transverse geometrical dimensions Geometrical specifications National standard regulations (2) The shapes of the upper punch, the bottom punch and the bottom punch are basically the same, but the length and length are different. The materials are all selected from 3Cr2W8V, and the heat treatment hardness is 43~48HRC. Dimensional design specification The formation of the nut blank process is a process of changing the cylinder into a hexagonal shape, which can be converted according to the law of volume invariance. The material consumption of the nut blank consists of two parts: one is the volume of material actually consumed by the standard nut, and the Other is the machining allowance volume of the two planes machined. Generally take the maximum thickness of the nut plus 3-4mm, see the nut blank.
Shentou square neck bolt squeezing process No. - Tractor Co., Ltd. (Luoyang, Henan 471004) Wu Liwei Ding Ningjie Zhao Hongmin He Wanqi countersunk square neck bolt (see) is the part of our company's high horsepower tractor shovel 7, demand In the past, it was formed by the method of upsetting, and the four-force was not full, and the life of the mold was low. After more than one year of practice, the use of squeezing and compounding technology has effectively solved the above problems and achieved good economic benefits. The upsetting forming process (see) is carried out on a single T-bit double-click automatic cold heading machine.镦 Chaos Quartet, refined square formation. In order to reduce the degree of deformation of the head, the upsizing process of the bar obtained by using the diameter of the approximate square is the following problems: (1) the upsetting force is large, the life of the forming die is low, and the square of the forming die is formed. With 75 people who are subject to the unit side ffi force P, and the median forging force (see)::, the unit type of forging force on the four aspects of the die, MPa P2 acting on the unit of the 75 cone t Upsetting force, shape complexity factor of Z workpiece, Z = 1.8/V mold shape factor of different forming methods, /V <7, strength limit of metal material, MPa, where a coefficient of influence of coarse shape, =2.0 / /Coefficient of friction,"=0.2,4 The maximum area of ​​the head in contact with the mold, mm2, /1=(1/4)Kx 2l2H The height of the head after upsetting, mm, the circumference of the upset after S forming Length, mm, S, P' blank calculation process: hexagonal volume:, =.866m, round inner table volume: actual consumption material volume: y=r(5)~6172 two kinds of 6 nuts, for example, selected The billet diameter and material length are listed in Table 4. Table 4 6 kinds of nut forging forming blank diameter and material length specification nut hair bad child f11
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