Production Process Guidance of Leaf Springs－Eyes wrapping (Part 6)

Production Process Guidance of Leaf Springs

－Eyes wrapping (Part 6)

1. Definition:

Heat the spring flat bars to a specified temperature, and then use special equipment and tooling molds to roll the ends of the spring flat steel into 1 / 4, 1 / 2, 3 / 4 circular eyes or other arcs.

Relevant dimensions of eyes wrapping technology are shown in Figure 1 below.

(Figure 1. Schematic diagram of eyes wrapping)

2. Application:

The 2nd leaf or 3rd leaf of a leaf spring.

3. Operating procedures:

3.1. Inspection before eye wrapping

Before wrapping the eyes, check the inspection qualification mark of the previous process of spring flat bars, which must be qualified. At the same time, check the specifications of spring flat bars(width, thickness and length), only they meet the process requirements, the wrapping process can be allowed to start.

3.2. Heating

Heating with furnace, the furnace temperature is controlled at 900-1000 ℃, and the heating length of spring flat bar = flat bar length / 2-L1+40mm. If the heating equipment fails for more than 10 minutes during the heating process, the heating shall be stopped, and the heated spring flat bar shall be pulled out of the furnace to avoid over-heating and over-burning.

3.3. Selection of wrapping mandrel

According to the shape and size data of the wrapped eyes, select the suitable wrapping mandrel.

3.4. Positioning of eye wrapping

When wrapping a eye, it is positioned by the central hole. If it is parabolic spring flat bar, the flat side of the spring flat bar shall be placed upward (and the tapered inclined plane side of the bar shall be downward), and then wrapping.

3.5. Eye wrapping inspection

When wrapping a eye, first piece of spring steel flat bar must be inspected firstly. Only it pass the first inspection, the mass production can be carried on.

See Table 1 for the inspection frequency after the first inspection to avoid unqualified products in the production process. The tests related to wrapping eyes are as follows:

1) The symmetry detection of edge cutting and corner cutting of wrapped eyes are shown in Figure 2 below.

(Figure 2. Symmetry detection of edge cutting and corner cutting of wrapped eyes)

2) The symmetry detection of the eyes wrapping process is shown in Figure 3 below.

(Figure 3. Symmetry detection of wrapped eyes process)

3) Shape detection of wrapped eyes, as shown in Figure 4 below.

(Figure 4. Shape detection of wrapped eyes)

3.6. Material Management

The eye wrapped spring steel flat bars shall be stacked neatly. It is forbidden to place them at will, resulting in surface bruises. The inspection qualification marks shall be made and the work transfer cards shall be pasted.

4. Inspection standards of eyes wrapping (Refer to the standard: GB/T 19844-2018 / ISO 18137: 2015 MOD Leaf Spring - Technical Specifications):

Measurements according to figure 1 and figure 2, the inspection standards of eyes wrapping are shown in table 1 below.

Compiled by  WONDEE Autoparts

2022-4-21