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Working principle of cold heading machine

  • Author:Zoe Jia
  • Release on:2023-05-26
The cold heading machine is a special equipment based on piers and specially used to mass-produce nuts, bolts and other fasteners.
  The world's first cold heading machine originated in Germany.
  Cold heading process
  (1) According to the theory of metal plasticization, the nut cold heading machine exerts a certain pressure on the metal blank at room temperature, so that it produces plastic transformation in the mold cavity and is formed according to the specified shape and size.
  (2) It is necessary to choose high-quality "plastic" good metal materials, such as rivet screw steel, whose chemical composition and mechanical properties have strict standards.
  (3) Nut forming machine bolts and nut forming machinery have multiple models and series of models. The equipment has reliable performance, high efficiency and stable product quality.
  (4) The product forming upsetting force is large, the configuration power is in, and the equipment investment is large at one time. Therefore, the production specification M24 and below is the most economical.
  (5) It has better surface quality and high dimensional accuracy. Due to the cold work hardening in the upsetting process, the amount of deformation should not be too large. Reduces cracking.
  (6) The multi-station cold heading machine process is applicable to products with large batches and various specifications, auto and motorcycle spare parts, etc., so as to reduce costs.
  The modern cold heading machine has been increased from the simple two-station in the past to multiple stations, and the latest varieties in China are 5 mold, 6 mold 6 mold extended cold heading machine.
  Process flow analysis of cold heading machine
  The forming of the bolt head adopts cold heading plastic processing, compared with the cutting process, the metal fiber (metal retention line) is continuous along the shape of the product, and there is no cutting in the middle, thus improving the strength of the product, especially the excellent mechanical properties. The cold heading forming process includes cutting and forming, single station click, double-click cold heading and multi-station automatic cold heading . An automatic cold heading machine performs stamping, upsetting, extrusion and diameter reduction processes in several forming dies. The processing characteristics of the original blank used by the single-station or multi-station automatic cold heading machine are determined by the size of the bar stock with a material size of 5-6 meters long or the wire wire with a weight of 1900-2000KG, that is, the processing technology is characterized by the fact that the cold heading forming does not use a pre-cut single piece blank, but adopts the automatic cold heading machine itself by bar stock and wire wire cutting and upsetting (if necessary) blank. Before extruding the cavity, the blank must be shaped. By shaping, blanks that meet the process requirements can be obtained. Before upsetting, resizing and positive extrusion, the stock does not need to be shaped. After the blank is cut, it is sent to the upsetting station. This station can improve the quality of the blank, reduce the forming force of the next station by 15-17%, and extend the mold life, and the bolt can be reduced multiple times.
  1. Cut the blank with a semi-closed cutting tool, the easiest way is to use a sleeve cutting tool; The angle of the incision should not be greater than 3 degrees; When using an open cutting tool, the incision angle can reach 5-7 degrees.
  2. The short-size blank should be able to be flipped 180 degrees during the transfer process from the previous station to the next forming station, so as to give full play to the potential of the automatic cold heading machine, process fasteners with complex structures, and improve the accuracy of parts.
  3. The punch return device should be installed on each forming station, and the die should be equipped with a sleeve type jacking device.
  4. The number of forming stations (excluding cutting stations) should generally reach 3-4 stations (more than 5 under special circumstances).
  5. During the effective service life, the structure of the main slide guide rail and process parts can ensure the positioning accuracy of punches and dies.
  6. The terminal limit switch must be installed on the baffle that controls the material selection, and attention must be paid to the control of upsetting force.
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