Part V Process Flow

Chapter 1 Annealing

1、 Purpose: Heat the wire to an appropriate temperature, maintain it for a certain period of time, and then slowly cool it down to adjust the crystalline structure, reduce hardness, and improve the room temperature processability of the wire.

2、 Homework process:

（1） Feeding: Hang the products that need to be processed into the furnace, paying attention to the furnace cover being tightly closed. Generally, one furnace can process 7 rolls (about 1.2 tons/roll) simultaneously.

（2） Heating up: Slowly (about 3-4 hours) raise the temperature inside the furnace to the specified temperature.

（3） Insulation: Material 1018 and 1022 wires are kept at 680 ℃ -715 ℃ for 4-6 hours, material 10B211039, and CH38F wire is kept at 740 ℃ -760 ℃ for 5.5-7.5 hours.

（4） Cooling: Slowly (about 3-4 hours) lower the temperature inside the furnace to below 550 ℃, and then cool it down to room temperature with the furnace.

3、 Quality control:

1. Hardness: The hardness of 1018 and 1022 wire after annealing is HV120-170, and the hardness of medium carbon wire after annealing is HV120-180.

2. Appearance: There should be no oxide film or decarburization on the surface.

Chapter 2 Pickling

1、 Purpose: To remove the oxide film on the surface of the wire and form a layer of phosphate film on the metal surface, in order to reduce the scratches on the tool and mold during wire drawing, cold stamping or forming processes.

2、 Homework process:

（1） Acid washing: Immerse the entire disk element in three hydrochloric acid tanks at room temperature and a concentration of 20-25% for several minutes to remove the oxide film on the surface of the wire.

（2） Clear water: Remove hydrochloric acid corrosion products from the surface of the wire.

（3） Oxalic acid: increases the activity of metals to make the film generated in the next process denser.

（4） Film treatment: Immerse the disk element in phosphate, and the steel surface comes into contact with the chemical treatment solution. The steel dissolves to form insoluble compounds (such as Zn2Fe (Po4) 2 · 4H2O), which adhere to the steel surface to form a film.

（5） Clear water: Remove residual substances from the surface of the film.

（6） Lubricant: Due to the low friction coefficient of phosphate film, it cannot provide sufficient lubrication during processing. However, it reacts with metal soap (such as sodium soap) to form a hard metal soap layer, which can increase its lubrication performance.

Chapter 3: Drawing Lines

1、 Purpose: Cold pull the plate element to the desired wire diameter. In practice, for some products, it can be divided into two stages: rough extraction (peeling) and fine extraction.

2、 Homework process

（1） Small wire drawing: Due to the minimum specification of 5.5mm for the disk element used by our company, most small screws (imperial 14 # (inclusive) and below, metric M5 and below) require smaller wire diameters, and the deformation of small screws during molding is significant. In order to reduce the processing stress caused by cold drawing and ensure the machinability of the wire, the cold drawing of the wire is divided into two stages. Firstly, a continuous wire drawing machine is used to roughly draw the coil element to a certain wire diameter (to ensure that the precision drawing reduction rate is less than 15%, as shown in the attached table), and then the annealing is carried out (as shown in Chapter 1) to eliminate the processing stress caused by rough drawing.

（2） Large wire drawing: After pickling, the coil element is cold drawn to the desired wire diameter by a wire drawing machine. Suitable for wires used in large screws, nuts, and teeth.

3、 Selection of disk elements:

（1） Hexagonal bolts, hexagonal wood screws, carriage screws

（2） , Nut

（3） Tooth strips

Chapter 4 Forming

1、 Purpose: To achieve the shape and length (or thickness) of semi-finished products by cold forging (or hot forging) of wire rods.

2、 Bolt (screw) forming (heading):

（1） Machine model (specification) selection:

（2） Homework process:

1. Hexagon bolt (four die four punch or the third mock examination three punch)

(1) Cutting: By moving the movable scissors in one direction, the wire stuck in the cutting die is cut into the desired blank material.

(2) One punch: The back punch presses against the raw material and compresses it with the die, forming the initial shape. Then, the back punch pushes out the raw material.

(3) Second punch: The raw material enters the second punch, and is extruded by the second die. The raw material is flattened and round, and then pushed out by the rear die.

(4) Three punch: The raw material enters the third punch and is cut by a hexagonal three punch die, forming a preliminary hexagonal head of the raw material. Then, the rear punch pushes the raw material into the third punch, and the cut material is cut from the hexagonal head, forming a hexagonal head.

2. Carriage bolt (the first mock examination and two punches)

3. Hexagon socket bolt (the third mock examination and three punches)

4. Hexagon washer head small screw (the third mock examination three punch)

5. Small screw (general head type the first mock examination and two punches)

(1) Cutting: By moving the movable scissors in one direction, the wire stuck in the cutting die is cut into the desired blank material.

(2) One punch: Fix the mold and use one punch to preliminarily shape the product head, so that it can be fully formed in the next stroke. When the product is a straight cut groove, one die is concave and elliptical groove. When the product is a cross groove, one die is concave and square groove.

(3) Second punch: After the first punch, the punch runs as a whole, and the second die moves towards the front of the punch. At the same time, the second die runs forward to finally shape the product. Afterwards, the blank material is pushed out by the back punch.

3、 Hot hitting:

（1） Applicable specifications:

（2） Homework process:

Heating: Use heating equipment to heat one end of the raw material to a white hot state, and set the heating temperature and time according to the product specifications. Generally, heat for 7-10 seconds for 3/4 or less, and for about 15 seconds for 7/8-1 inches.

Molding: Quickly transfer the heated raw material to the molding machine, fix it with a back seat, clamp it with a mold, and impact the raw material with a head mold to form it. The distance of the rear seat can be adjusted according to the length of the raw material.

3. Bundle bar: Use compression on the bundle bar machine to shrink the product bar.

4、 Nut forming:

（1） Machine model (specification) selection:

（2） Homework process:

1. Cutting: The wire is cut into the desired raw material by combining the inner blade die (410) with the cutting blade (301).

2. One punch: With the cooperation of the front die (111), stroke die (411), and rear punch rod (211), the deformed and uneven cut blank is shaped, and the blank is pushed out by the rear punch rod (211).

3. Second punch: The operating clamp (611) clamps the raw material from the first punch to the second punch. The front punch (112), stroke die (412), and rear punch rod (412) work together to further shape the raw material and strengthen the flattening and corner filling effect of the first punch. Then, the rear punch rod (212) pushes out the raw material.

4. Three punch: The operating clamp (612) clamps the raw material from the second punch to the third punch, and the front die (113), stroke die (413), and rear punch rod (213) work together to squeeze the raw material again so that the lower punch can fully form it. Then, the rear punch rod (213) pushes out the raw material.

5. Four punch: The operating clamp (613) clamps the raw material from three punch to four punch, and the nut is fully formed by the front die (114), stroke die (414), and rear punch rod (214). The thickness of the nut is adjusted by controlling the thickness of the iron filings, and then the raw material is pushed out by the rear punch rod (214).

6. Five punch: The operating clamp (614) clamps the raw material from four punch to five punch, and the fully formed raw material is punched by the front die (119) and the discharge tray (507), and the broken iron chips enter the bottom of the punching die to finally complete the formation of the nut. The head mark of the nut is formed during this process.

Chapter 5: Grinding Teeth (Attacking Teeth)

1、 Purpose: To roll or tap the formed semi-finished product to achieve the desired thread. In practice, it is called rolling teeth for bolts (screws), rolling teeth for tooth strips, and tapping teeth for nuts.

2、 Rolling teeth: Rolling teeth is the process of fixing one tooth plate and moving another movable tooth plate to move the product, using compression to cause plastic deformation of the product and form the desired thread.

（1） Machine model (specification) selection:

（2） Quality control:

1. Small outer diameter of teeth:

The first reason may be that the dental arch is not full, and adjusting the relative position of the dental plate is sufficient. Secondly, it may be that the effective diameter of the molding is too small.

2. Tooth root defect:

For tooth root peeling (such as wood screws), adjust the sharp angle and straight angle of the fixed tooth plate, and push the sharp angle inward appropriately.

3. Tooth tip defect (small tooth rolling):

The symptoms of tooth tip defects include: cracks in the tail tip, burning, crooked tail, broken tail, blunt tail, etc. It can be improved by adjusting or replacing the tooth plate.

4. Poor appearance:

Appearance defects include: crooked shaft, rough tooth base diameter, insufficient tooth ridge, and tail teeth not being rubbed to the tip. It can be improved by adjusting the tooth plate.

3、 Tapping: Tapping is the process of threading a formed nut with a thread to create the desired thread.

（1） Machine model (specification) selection:

（2） Quality control:

A common quality issue during the process of tooth tapping is tooth tightness, which is usually caused by bending of the straight part of the tooth tapping handle, blunting of the tooth tapping, exceeding the effective diameter tolerance, and misalignment of the upper and lower running tracks. To address the causes of tooth tightness, measures such as orthodontic treatment, replacement of teeth, or adjustment of the track can be taken.

4、 Rolling teeth: Rolling teeth are two corresponding screw rollers that rotate forward, using compression to cause plastic deformation of the product and form the required thread. Rolling teeth are usually used for dental strips.