Production Process Guidance of Leaf Springs - Eyes rolling (Part 5)

Production Process Guidance of Leaf Springs

－Eyes rolling (Part 5)

1. Definition:

Heat the spring flat bars to the specified temperature, and then use special equipment and tooling molds to roll the ends of the spring flat bar into circular eyes.

Relevant dimensions of eye rolling technology are shown in Figure 1 below.

(Fig. 1 Schematic diagram of eyes rolling)

2. Application:

The first leaf or / and last leaf of a leaf spring.

3. Operating procedures:

3.1. Inspection before eye rolling

Before rolling 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, only they meet the process requirements, the rolling 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 + 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 rolling mandrel

The mandrel shall be selected according to the eye’s inner diameter and the drawing of the?rolling mandrel, and the lower die adopts R = D /2(R=radius of the eye, D= diameter of the rolling mandrel).

3.4. Positioning of end cutting and eye rolling

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

When eye rolling, it is still positioned by the central hole, and then the eye is rolled in different directions according to whether it is an upper ear or a lower ear.

3.5. Eye rolling?inspection

When rolling 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 rolling ears are as follows

1)?The?roundness detection of rolled eyes is shown in Figure 2 below.

2) The?horn hole detection of?rolled eyes is shown in Figure 3 below.

3) Rolled eye?shape detection, as shown in Figure 4 below.

(Fig. 2?Roundness detection of eyes rolling)

(Fig. 3. Horn hole detection of eyes rolling)

(Fig. 4.Shape detection of eyes rolling)

3.6. Material Management

The eye rolled 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 rolling(Refer to the standard: GBT 19844-2018 / ISO 18137: 2015 MOD Leaf Spring - Technical Specifications):

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

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