A forging method that uses a mold to upset metal bars at room temperature. It is usually used to make the heads of screws, bolts, rivets, etc. The forging blank material can be copper, aluminum, carbon steel, alloy steel, stainless steel, titanium alloy, etc. . Cold heading is mostly carried out on cold heading machines, which facilitates the realization of continuous, multi-station and automation. The cold heading machine can sequentially complete the processes of cutting, heading, accumulation, forming, chamfering, thread rolling, diameter reduction and trimming. The following is a brief introduction to the key points in the operation of cold heading machine equipment:
1. Characteristics of cold heading process
(1) According to the theory of metal plastic deformation, a certain pressure is applied to the metal blank at room temperature to cause plastic deformation in the mold cavity and mold it into the specified shape and size.
(2) Metal materials with good plastic deformation must be selected and have strict standards for their chemical composition and mechanical properties.
(3) Cold heading bolt and nut forming machinery has multiple models and series, with reliable equipment performance, high efficiency and stable quality.
(4) The workpiece forming and upsetting force is large, and the power equipment is expensive.
(5) The workpiece has good surface quality and high dimensional accuracy. Due to cold work hardening during the upsetting process, the deformation should not be too large.
(6) The cold heading process is suitable for large batches of workpieces of various specifications.
2. Tips for operating the cold heading machine
(1) The diameter of the steel bar or steel wire should meet the requirements of the multi-station cold heading machine, and steel bars that are too thick or too thin cannot be cold headed.
(2) Within the allowable range of the cold heading diameter of the multi-station cold heading machine, the position of the clamp can be adjusted according to the required anchor head size in order to obtain a suitable steel bar extension allowance.
(3) Rust must be removed and straightened in the area of the cold heading part of the steel bar.
(4) The ends of the steel bars should be ground flat to ensure the accurate shape of the cold heading anchor head.
(5) The steel bars must undergo a tensile test after heading to check whether the strength of the anchor head is qualified.
(6) Use a semi-closed cutting tool to cut the blank. The simplest method is to use a sleeve-type cutting tool.
(7) Each molding station should be equipped with a punch ejection device, and the die should be equipped with a sleeve-type ejection device.
(8) During the effective period of use, the structure of the main slide rail and process components can ensure the positioning accuracy of the punch and die.
(9) A terminal limit switch must be installed on the baffle that controls material selection, and attention must be paid to the control of the upsetting force.
3. Three maintenance systems for cold heading machines
The three-maintenance system includes: daily maintenance, primary maintenance and secondary maintenance of the cold heading machine.
(1) The three-maintenance system is a compulsory maintenance system that focuses on maintenance and pays equal attention to maintenance on equipment.
(2) Institutionalization means stipulating different maintenance cycles and maintenance times based on different equipment and different conditions and strictly implementing them.
(3) For regular maintenance work, working hour quotas and material consumption quotas must be established and assessments must be carried out according to the quotas.
(4) Enterprises should regularly conduct self-inspections and mutual inspections, and carry out equipment inspections.