Abstract: This article introduces the improved design and machining process of sliding bearings for press machines.

Keywords: press machine; Sliding bearings; processing

In the current production of universal crank presses, the crank support bearings, the large gear bushings on the inner and outer sleeves of the rigid clutch, and the connecting rod big end bearings are all sliding bearings made of cast copper alloy (Figure 1). This is selected based on the characteristics of low operating speed and high load of the press machine. Therefore, when setting the timer, as long as it can meet the pressure acting on the sliding bearing, the size of its wall thickness is only related to the processing technology. On the premise of meeting the requirements for the use of the press and facilitating assembly, sliding bearings are generally designed as integral or split type bearing shells.

With the promotion and application of new technologies and processes, it is not difficult to identify the problems of existing sliding bearings through analysis and research: inadequate structural dimensions, material waste, and high production costs. Therefore, it is necessary for designers to optimize the structural dimensions of the press sliding bearings based on the improvement of processing technology, while ensuring that the usage requirements are met, in order to achieve the goal of reducing consumption and increasing efficiency.

Figure 1 Sliding Bearing

(a - Left and right crankshaft support bearings; B-large gear liner; C-connecting rod big end bearing; D-wire cutting production of bearing shells

1. Improvement targets and measures

Taking the J23-100 press as an example, analyze the improvement effect of sliding bearings.

The sliding bearings of the machine have left and right crankshaft support bearings, large gear bushings on the inner and outer sleeves of the rigid clutch, and connecting rod big end bearings.

1.1 Left and right crankshaft support bearings (Figure 1a)

The bearing is installed in the bearing seat and fixed to the shaft hole of the machine body together with the bearing seat. It can be disassembled and installed together with the bearing seat. Generally, the bearing is fixed to the bearing seat with saddle screws to prevent radial and axial displacement of the bearing during the operation of the press. So the previous processing technology: casting → machining → installing the bearing seat → matching the saddle screw → scraping the inner hole. The disadvantage of this process is that the dimensional tolerance of the inner hole after its outer circle is pressed into the bearing seat is difficult to meet the requirements of the drawing, and necessary scraping is required during assembly. The current process is: casting → leaving a certain margin in the inner hole, machining the rest → installing the bearing seat → matching with saddle screws → correcting the outer circle and end face of the bearing seat, and turning the inner hole of the bearing to meet the requirements. Compared with previous processes, the current process is easier to ensure the dimensional tolerance of the inner hole. If the wall thickness of the bearing is appropriately reduced, it will not affect the accuracy and effectiveness of the bearing.

1.2 Large gear bushing (Figure 1b)

The liner is used in pairs, so its basic requirement is that the size tolerance of the inner hole and outer circle should be consistent, which is the best. To meet this requirement, the process of processing the original single piece has been changed to casting (two pieces are connected together and the length of the clamping process is increased) → inner hole, outer circle, and step (the total length is the length of the two pieces plus the width of the cutting knife) → cutting according to the length of the single piece and trimming the cutting end face. After adopting this process, the wall thickness of the liner can be appropriately reduced, which can achieve the same precision requirement of two pieces per set without affecting the quality of use.

1.3 Connecting rod big end bearing (Figure 1c)

According to the linear running characteristics of the press slide, the guide rail on the slide body should control the guiding accuracy during operation, so the bearing flange does not work. However, the previous processing techniques (casting → planing the bonding plane → soldering the welding plane → machining → separating two pieces and removing the solder) still have drawbacks - the wall thickness cannot be too small, otherwise it is difficult to weld firmly or deformation may occur during machining, affecting accuracy.

With the promotion and application of wire cutting technology, the machining process of bearings has been changed to: casting (integral) → machining → wire cutting to separate two pieces (Figure 1d). Obviously, this processing technique is superior to previous processing techniques. Therefore, it is also feasible to appropriately reduce the wall thickness of the bearing.

1.4 Bimetallic bearings

The bearings shown in Figures 1a and 1b can also adopt a bimetallic structure. The outer layer is made of base metal, and the inner hole is made of cast copper alloy. Sliding bearings with a general aperture of less than 200mm, copper alloy wall thickness of 3mm, are obtained by centrifugal casting. If this structure is used, the material saving effect is significant.

2026 April 2nd Week Marginal Product Recommendation

Material Specification Sheet–MG-6:

Material specification sheet – MG-6 is Ball and roller bearing steel according to EN ISO 683-17. Ball and roller bearing steel for balls and rollers of any dimension,rings and discs up to 30mm effective thickness.

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