According to different non-standard screws, we will choose different production methods. Due to the limitation of appearance, some non-standard screws can only be produced by machining. However, most of the non-standard screws are still processed and produced by cold heading. So what are the characteristics of cold heading forming test?

Usually in the cold heading process, the head forming of the non-standard screw adopts cold heading plastic processing, and the cutting and extrusion forming process has more advantages than the expansion process. Screw customization, for example, the dimension inspection items for hexagonal nuts are specified as thread general gauge, thread stop gauge, thread minor diameter, opposite side width, diagonal dimension, nut height, and the perpendicularity of the nut bearing surface and the thread axis; while the flat washer is specified as the inner diameter , outer diameter, thickness, coaxiality of the outer circle to the inner hole and flatness, etc. As for the mechanical performance inspection items, hardness and tensile strength are specified for hexagonal nuts, while only hardness is specified for flat washers.

An automatic cold heading machine distinguishes how many forming dies are used for multi-station processes such as stamping, upsetting, extrusion and diameter reduction. Screw customization, for example, the dimension inspection items for hexagonal nuts are specified as thread general gauge, thread stop gauge, thread minor diameter, opposite side width, diagonal dimension, nut height, and the perpendicularity of the nut bearing surface and the thread axis; while the flat washer is specified as the inner diameter , outer diameter, thickness, coaxiality of the outer circle to the inner hole and flatness, etc. As for the mechanical performance inspection items, hardness and tensile strength are specified for hexagonal nuts, while only hardness is specified for flat washers. The processing characteristics of the original blank used by the single-mode or multi-station automatic cold heading machine are determined by the size of the bar with a material size of 5-6 meters or the size of the wire rod with a weight of 1900 to 2000KG, that is, the processing technology is characterized by Cold heading does not use pre-cut single blanks, but uses automatic cold heading machine itself to cut and upset (if necessary) blanks from bars and wire rods. Before extruding the cavity, the blank must be shaped, and the blank that meets the process requirements can be obtained by shaping. The size of the blank must be taken seriously. The shape of the blank before extrusion should be judged according to the situation of the whole machine, and the shape of the blank that is conducive to the flow of materials should be adopted. If the blank size is too large, that is, the cutting and extrusion allowance is too large, the required cutting and extrusion force will be larger, which will easily cause the life of the cutting and extrusion die to decrease, increase the possibility of accidental damage to the die, and consume raw materials; the cutting and extrusion allowance is too large. Small, the whole machine easily falls off after cutting and extruding, the shape is not complete, and the appearance quality cannot be satisfied.

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