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

Views: 0     Author: Wondee Autoparts     Publish Time: 2022-04-15      Origin: Wondee Autoparts

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.

Schematic diagram of eyes rolling

(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.

Roundness detection of eyes rolling

(Fig. 2 Roundness detection of eyes rolling)

Horn hole detection of eyes rolling

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

Shape 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.

Inspection Items

Diameter of eyes

Verticality and   parallelism of eyes

Shape of eyes

Roundness of eyes

Horn holes

Width of eyes

Length deviation of eyes

Surface quality of Eye rolling

Technical Requirements

According to the process card Requirements


Check according to   figure 4

Clearance after passing through the end of   plug gauge ≤ 0.3mm (check   according to figure 2)

Insertion depth of plug gauge stop ≤ B × 5%   (check according to figure 3)

According to the process card Requirements

L1±1.5Total   length L ± 3mm

Half length L1 ± 1.5mm


 There shall be no overheating, overburning and pressed iron oxide   scale. Bending within 75mm of the plane of the eye rolled end ≤ 0.5mm

Measuring and inspection tools


Plug gauge

Angular rule

Special ruler

Plug gauge

Plug gauge

Vernier Caliper

Tape measure

Visual inspection









Sampling method

Each batch shall be inspected according   to the first piece, middle pieces and last piece inspection, and the visual   inspection rate of eyes rolling surface quality is 100%.

Compiled by  WONDEE Autoparts


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