Production Process Guidance of Leaf Springs－Leaf Springs Assembling (Part 8)

Production Process Guidance of Leaf Springs

－Leaf Springs Assembling(Part 8)

1. Definition:

Leaf spring assembling is the working process of using special equipment and central bolts to combine the loose spring leaves into a leaf spring assembly. The leaf spring assembly is shown in Figure 1 below.

(Figure 1. Schematic diagram of leaf spring assembly)

2. Application:

Leaf spring assembly.

3. Operating procedure:

3.1. Preparation before spring assembling

Before assembling the leaf springs, the process card shall be checked first, and all components shall be prepared according to the process requirements. At the same time, check the sizes of loose leaves and components, spring assembling is allowed only there are inspection qualification marks in the previous processes.

For assembly which is parabolic leaf spring or single-piece paint requirements, the single-piece paint should be done first, and then the assembly is assembled.

3.2. Inspection and selection of spring leaves and components

When assembling a leaf spring, pay attention to the selection of camber height, central hole position, side bending, distortion, etc., and check the dimensions of various components according to the process requirements, especially pay attention to the requirements of the diameter and height of the central bolt head. If there is any unqualified one, it shall be removed.

The following points shall be paid attention to when selecting the spring leaves:

1) The clearance between the end of the eye rolled leaf and the eye wrapped leaf is between 3-6mm;

2) The lateral dislocation of both ends of the main leaf shall be≤1.5mm;

3) Dislocation of center hole shall be≤1.0mm

Within any 75mm length range, the clearance between leaves of conventional multiple leaf springs is ≤ 0.5mm, and the parabolic springs shall be kept between 3-5mm, and the transition shall be uniform;

5) Graphite calcium base grease or graphite lithium base grease shall be applied between the leaves of conventional multi leaf spring , between the leaves at the center spacer of the parabolic leaf spring and between the leaves at the ends spacer of the parabolic leaf spring , and the coating width shall be ≥ 1 / 3 of the spring width.

3.3. Requirements of spring assembling

After the leaf spring is assembled according to the assembly drawing, it shall be checked to ensure that the spring leaves and central spacers are not skewed, the clearance between the eye rolled leaf and the eye wrapped leaf is reasonable, and the appearance quality without unreasonable bending. Then preload the leaf spring assembly twice according to the action length and preloading stroke provided by the assembly drawing or process. Before and after leaf springs preloading, leaf spring camber height shall be measured according to the methods provided by the assembly drawing or process to check whether the leaf spring camber height meets the process requirements;

3.4. Inspection after the leaf springs assembling

When assembling a leaf spring, first set of leaf spring assembly must be inspected firstly. Only it pass the first inspection, the mass production can be carried on.

If there are requirements about camber height grouping or chord length classification, identification marks shall be made at the ends of leaf spring assembly;

3.5. Material Management

The assembled leaf springs 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 leaf spring assembly (Refer to the standard: GB/T 19844-2018 / ISO 18137: 2015 MOD Leaf Spring - Technical Specifications):

The inspection standards of leaf spring assembly are shown in Table 1 below.

Compiled by  WONDEE Autoparts

2022-5-9