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Screw Tightening Machine processing technology
Mar 13, 2018

A process of screw manufacturing: disk element - annealing - Pickling - drawing line - head - rolling - heat treatment - electroplating - packaging


The definition: refers to the original purchase from manufacturers of wire rod, a disc element includes the following parameters: brand, name, specification, material, furnace number or batch number, quantity / weight; the main chemical composition of the steel are: C, Mn, P, S, Si, Cu, Al, the the contents of Al and Cu as low as possible.

The annealing

First, the definition is: heating the wire to the proper temperature, holding it for a certain time, and then slowly cooling it, so as to adjust the crystal structure, reduce the hardness and improve the processing property of wire at room temperature. (2) operation process: feeding - heating - heat preservation - cooling. Quality control: hardness: material is 1018 and 1022, hardness is HV120-170 after annealing, material is medium carbon wire, hardness is HV120-180 after annealing, appearance: no oxide film and decarbonization phenomenon on the surface.

3 acid

Objective: remove the oxide film on the wire surface and form a phosphate film on the surface of the metal, so as to reduce the abrasion of the wire and rod and the cold die or forming process.

(2) operation process:

I, pickling: the whole disk is immersed in three hydrochloric acid tanks at normal temperature and concentration of 20-25% for several minutes respectively. The purpose is to remove the oxide film on the surface of the wire.

II. Clean water: remove the corrosion product of hydrochloric acid on the surface of the wire.

Third, increase the activity of oxalic acid: metal, in order to make the film a process generation is more compact.

IV, film processing: disc element immersed in phosphate, iron and steel and surface chemical treatment liquid contact, iron dissolved formation of insoluble compounds (such as Zn2Fe (Po4) 2 - 4H2o), attached to the formation of a coating on the surface of iron and steel.

V: clear water, membrane surface residue.

VI, a lubricant because the phosphate coating friction coefficient is not very low, lubrication can not give sufficient but when processing and metal soap (such as sodium soap) reaction to form metal soap hard layer, can increase the lubrication performance.

4. pumping line

Objective: to pull the disc cold to the required line. Practical for some of the products can be divided into roughing and finishing (peeling) pumping two stages.

Work flow

I small draw line: because the minimum size of the general disk is 5.5mm (the companies are different depending on the specific circumstances), while most of the small screws (British 14# (below), below the metric M5) require smaller line diameters and larger deformation when small screws are formed. In order to reduce the stress caused by cold drawing processing, ensure the wire processing, wire drawing will be divided into two stages, first using continuous wire drawing machine will offer yuan pumping crude to a certain diameter (to ensure the drawing area reduction ratio is less than 15%, after annealing, the principle) to eliminate rough machining pumping stress generated.

II large drawing line: after pickling, the disc element is drawn cold to the required line through the drawing machine. The wire used for large screws, nuts and teeth.

5. molding

The wire is forged by cold (or heat - forging) to achieve the shape and length (or thickness) of the semi-finished product.

(1) operation process:

I, six angle bolts (four die four blow or the third mock exam three)

(1), cut off: move through a movable scissors, cut the wire in the shear into the desired material.

(2), a punch: die blank die off after extrusion billet, preliminary molding, die after the blank is launched.

(3), two: blank into second punching die, extrusion die two, blank was flat, after the launch will die blank.

(4), three: blank into third punching die, die shear angle of three through six after the stock kernel, six head shape, after the blank into the die, die third, cutting off from six head, six head formation.

II, carriage bolts (the first mock exam at two)

Third, in six angle bolts (the third mock exam at three)

IV, six angle washer head screws (three at the third mock exam)

V, small screws (common head the first mock exam two)

(1), cut off: through the movable scissors one-way movement, cut the wire in the shearing mold into the desired material.

(2), one stroke: the die is fixed, and one die can make the head of the product shape initially so that the next stroke can be completely formed. When the product is a word cut ditch, one die is a concave and elliptical groove. When the product is a cross groove, a punch die is a concave and quadrangle groove.

(3), two flushing: after one stroke, the punching tool runs as a whole, and the two die moves toward the front of the punch, while the two die is running forward, and the product is finally formed. Followed by the blank bar after launch.

6. rolling teeth (tapping)

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