First, the choice of workpiece blank
The processing characteristics of the original blank used by single-station or multi-station automatic cold heading machine are determined by the size of the bar with a material length of 5-6 meters or the wire with a weight of 1900-2000KG, that is, the technological characteristics are that cold heading is not a pre-cut single blank, but the upsetting blank is cut by the automatic cold heading machine itself.
Second, the preparatory work
Before extruding the cavity, the blank must be shaped, and the blank that meets the technological requirements can be obtained through shaping, and the blank does not need to be shaped before upsetting, reducing diameter and positive extrusion. Sending the cut blank to the upsetting station can improve the quality of the blank, reduce the forming force of the next station 15- 17%, and prolong the service life of the die. Bolts can be reduced many times.
Three. Mid-term considerations
1. The simplest way to cut a blank with a semi-closed cutter is to use a sleeve cutter; The angle of the incision should not be greater than 3 degrees; When using an open cutter, the bevel angle of the incision can reach 5-7 degrees.
2. In the process of transferring short-sized blank from the previous station to the next forming station, it should be able to turn over 180 degrees, give full play to the potential of automatic cold heading machine, process fasteners with complex structures and improve the accuracy of parts.
3. Each molding station should be equipped with a punch material returning device, and the female die should be equipped with a sleeve ejection device.
4. The number of forming stations (excluding cutting stations) should generally reach 3-4 stations (more than 5 in special cases).
5. Within the effective service life, the structure of the main slider guide rail and process parts can ensure the positioning accuracy of the punch and the die.
6. The terminal limit switch must be installed on the baffle to control the material selection, and the upsetting force should be controlled.
Fourthly, precise measurement in the later period.
The precision that can be achieved by cold heading is also related to the choice of forming method and the working procedure adopted. The roundness of steel wire used to manufacture high-strength fasteners on automatic cold heading machine should be within the tolerance range of diameter. If the diameter of the steel wire does not reach the specified size, cracks or burrs will appear in the upsetting part or the head of the part. If the diameter is less than the size required by the process, the head is incomplete, and the edges and corners or thickened parts are unclear. In addition, it also depends on the structural characteristics, technological characteristics and state of the equipment used, the performance of the cold upsetting oil, the precision of the die and the die and the degree of wear.