Design of flexible riveting fixture for frame assembly

The frame assembly riveting jig is an important tooling in the frame production process, which can effectively ensure the positional accuracy of the stringer and the dimensional accuracy of the frame assembly. In order to be able to meet the production of a variety of models on a set of fixtures, the flexibility of the fixture must be achieved.

With the soaring sales of heavy-duty trucks, all automobile OEMs have adjusted production capacity planning in a timely manner to improve the company's production capacity. At the same time, due to the increasing variety of products, the difference is getting larger and larger. The frame assembly fixture of the original production line Sharing is no longer possible. However, the new production line needs to invest a lot of money and the cycle is longer. In order to reduce the investment and achieve rapid production, it is a good solution to design a universally configurable frame assembly flexible fixture.

As the main bearing part of the truck, the frame has high requirements on dimensional accuracy. At the same time, because the plate is thick (usually 7~10mm), the punching precision is difficult to guarantee, and the deformation is large in the free state. The positioning and clamping of the clamp ensures the size and positional accuracy of the frame during the riveting process.

This paper introduces a flexible riveting fixture for a heavy-duty truck frame assembly. By combing and analyzing the differences between the various models of the JAC heavy-duty truck, the position of the clamping point is determined so that the fixture can meet the twenty The rest of the frame length and width of the frame riveting positioning function, the degree of flexibility is very high. At the same time, the accuracy of the frame assembly is also greatly improved, which effectively ensures the mass production of the frame. The design idea of ​​the fixture in terms of flexibility is forward-looking and advanced, and it also has some guidance for other similar projects.

Frame assembly

1. Frame parameters

(1) Three-story longitudinal frame frame with three different widths (width 840mm), additional auxiliary beam frame (width 854mm) and thick auxiliary frame (width 860mm).

(2) The lengths of the frame frames of 16 different lengths are 6020 mm, 6590 mm, 6970 mm, 7010 mm, 7070 mm, 7339 mm, 7460 mm, 7910 mm, 8120 mm, 8127 mm, 9540 mm, 9600 mm, 9640 mm, 9987 mm, 10 600 mm and 11 600 mm, respectively.

2. Production beat

The production cycle of the station is 10min/set, which can realize the production capacity of 15,000 units per shift.

Fixture workflow

The working process of the riveting fixture of the frame assembly is shown in Figure 1.

Figure 1 fixture workflow

It mainly includes the following five aspects:

1) Undertake the stringer assembly transferred from the previous station.
2) Turn the stringer 90° and position it for clamping.
3) After pre-positioning the beams between the stringers, the clamps are closed toward the middle, so that the stringers hold the beams.
4) After manually installing the rivet, the clamp continues to close to the middle, so that the stringer and the beam are merged into place.
5) After the riveting of the stringer and the beam is completed, the frame is transferred to the next station.

Fixture technical requirements

The technical requirements for the frame assembly fixture are as follows:

1) The selection of the clamping position should avoid the position of the beam and the passage of the rivet clamp. At the same time, the number of clamping points of the short frame is not less than three.
2) The quality of the frame is nearly 2t, and a motorized roller with sufficient power should be used.
3) The fixture has a correction function for the straightness of the longitudinal direction of the longitudinal beam, which can meet the requirements of the longest model, the correction range can reach 20mm; at the same time, in the adjacent hydraulic clamping unit, the correction range can reach 8mm.
4) The straight section of the longitudinal beam should be clamped on both sides of the ventral surface and the airfoil, and the product design parameters can be guaranteed.
5) The hydraulic system should ensure that the system pressure can reach 1400N/cm2, and the pressure-holding function is provided after the actuator is in place (the hydraulic pump is unloaded at this time to avoid heat, and the clamping force of the clamping mechanism during the unloading of the hydraulic pump) constant).
6) Fixture processing assembly accuracy requires that the fixture positioning surface tolerance does not exceed 0.2mm.

Silicone solid spoon

Silicone Spoon,Silicone Spoon Baby,Silicone Spoon Mold,Small Silicone Spoon