Techniques for manufacturing stainless steel screws;

1. Stainless steel spiral coil: ① Definition: refers to the original wire rod purchased from the manufacturer. A coil mainly includes the following parameters: brand, product name, standard, raw materials, heat number or batch number, quantity/weight; ② The main chemical components in steel are C, Mn, P, S, Si, Cu and al, and the lower the content of Al and Cu, the better.

3. Annealing of stainless steel screws: ① Definition: heating the wire to a suitable temperature for a certain period of time, and then gradually cooling to adjust the crystal arrangement, reduce the hardness and improve the room temperature processability of the wire. ② Work flow: feeding-heating-heat preservation-cooling. ③ quality control: hardness: the raw materials are 10 18 and 1022, and the hardness after annealing is HV 120- 170, and the raw materials are carbon fibers, and the hardness after annealing is HV120-/. Appearance: There should be no oxide film and decarburization on the surface.

3. Stainless steel spiral pickling:

① Intention: Remove the oxide film on the wire surface and form a phosphating film on the metal surface, so as to reduce the scratches on tools and molds during wire drawing, cold pier or molding.

(2) Work flow of stainless steel screws:

1. Pickling: Immerse the whole coil in three hydrochloric acid tanks with concentration of 20-25% for several minutes at room temperature to remove the oxide film on the wire.

Two. Clear water: remove hydrochloric acid corrosion products on the surface of steel wire.

Ⅲ. Oxalic acid: Adding the activity of metal makes the film produced in the next process finer.

Ⅳ. Coating treatment: the disc is immersed in phosphate, and the steel surface contacts with the chemical treatment solution, and the steel dissolves to generate insoluble compounds (such as Zn2Fe (PO4) 2.4H2O), which are attached to the steel surface to form a coating.

ⅴ. Clear water: remove the residue on the membrane surface.

ⅵ. Smoothing agent: Because the friction coefficient of phosphating film is not very low, it can't give enough smoothness during processing, but it reacts with metal soap (such as sodium soap) to form a solid metal soap layer, which can increase its smoothing function.

Stainless steel screw

4. Stainless steel screw drawings

① Intention: Cold-draw the coil to the required wire diameter. In practice, some commodities can be divided into two periods: rough pumping (hulling) and fine pumping.

② Work flow

Ⅰ Small wire drawing: As the minimum standard of disc-shaped components is usually 5.5mm (different from company to company), most small screws (English 14# or below, metric M5 or below) require smaller wire diameter, which leads to large deformation during molding. In order to reduce the processing stress caused by cold drawing and ensure the machinability of wire rod, the cold drawing of wire rod is divided into two sections. Firstly, the wire rod is roughly drawn to a certain wire diameter by a continuous drawing machine (based on ensuring that the surface reduction rate of fine drawing is less than 15%), and then annealed to eliminate the processing stress caused by rough drawing.

Ⅱ large wire drawing: after pickling, the coil is cold-drawn to the required wire diameter by wire drawing machine. Suitable for wire of large screws, nuts and racks.

5. Spiral forming of stainless steel: the wire is cast in the cold chamber (or hot chamber) to reach the shape and length (or thickness) of the semi-finished product.

(1) workflow:

Ⅰ. Hexagon bolts (four dies and four punches or three dies and three punches)

(1). Interception: After the movable scissors move in one direction, the wire stuck in the shearing die is cut into the required blank.

(2) Punching for the first time: after die pressing, the blank is kneaded on the blank die to start forming, and then the blank is pushed out by the back die.

(3) secondary punching: the blank enters the secondary punching die, is flattened by the secondary punching die, becomes flat and round, and then is pushed out by the rear punching die.

(4) Third stamping: the blank enters the third stamping die, and after being cut by the hexagonal third stamping die, the blank begins to form a hexagonal head, and then the blank is pushed into the third stamping die by the post stamping die, and the blank is cut from the hexagonal head and formed by the hexagonal head.

Ⅱ, carriage bolts (one die and two punches)

Ⅲ. Hexagon socket head bolt (three dies and three punches)

Ⅳ. Hexagon head screws (three dies and three punches)

ⅴ. Small stainless steel screws (usually one die and two punches are used for the head)

(1). Interception: After the movable scissors move in one direction, the wire stuck in the shearing die is cut into the required blank.

(2) Punch: The die is fixed, and the head of the goods is molded with the stamping die, so that the next stroke can be completely molded. When the goods are cut into straight lines, the mold is concave oval, and when the goods are cut into cross grooves, the mold is concave square.

(3) the second punching: after the first punching, all punching tools are operated, the second punching die moves to the front of the punching die, and the two punching dies move forward together, so as to finally shape the goods. After that, the blank is pushed out by the rear punch.

6. Stainless steel thread rolling (tapping)

I. Intention: Roll or tap the molded semi-finished product to achieve the required thread. In actual operation, bolts (screws) are called hobbing, teeth strips are called hobbing, and nuts are called tapping.

Ⅱ. Gear hobbing: Gear hobbing is to fix one toothed plate, and the other movable toothed plate drives the commodity to move, so that the commodity is plastically deformed by kneading to form the required thread.

Three quality control:

① Small outer diameter of teeth: the primary reason may be that the teeth are not full, so it is enough to adjust the relative orientation of the dental plate, and the secondary reason may be that the useful diameter of molding is too small.

② Bad tooth bottom: For tooth bottom peeling (such as wood screws), adjust the acute angle and vertical angle of the fixed tooth plate and push the acute angle inward appropriately.

③ Bad cusp (small teeth rolling): Bad cusp phenomena include: cracked tail tip, burning, crooked tail, broken tail, blunt tail, etc. It can be improved by adjusting the dental plate or replacing the dental plate.

4. Bad appearance: Bad appearance phenomena include: crooked strip, rough tooth bottom diameter, unsatisfactory teeth, no friction between tail teeth and tail tip, etc. It can be improved by adjusting the dental plate.

Ⅳ Gear hobbing: Gear hobbing is that two corresponding spiral rollers roll forward, and the product is plastically deformed by kneading to form the required thread. Hobbing is usually used for tooth belts.