RU2276293C1 - Method of manufacture of bearing unit - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: invention relates to manufacture of bearing units forming supports of rotating parts of machines. Proposed method includes assembling of antifriction bearing from outer and inner races, solids of revolution, cage, bearing shields, mounding of bearing race into plasticized material of part of mechanism and mounting part with bearing into housing of mechanism with forming of support unit and adjusting of clearances to preset fits. Race is molded into plasticized material of blank separately from bearing. Blank is located to free surface of race on machine tool and is machined to get size and shape of required accuracy and ready part with molded-in race is assembled into antifriction bearing as common assembly unit.

EFFECT: increased accuracy of manufacture, longevity and rigidly of parts of bearing unit.

2 dwg

Description

The invention relates to the field of general engineering, and in particular to methods for manufacturing bearing assemblies forming supports for rotating parts of machines and mechanisms.

A known method of manufacturing a bearing assembly, pre-assembling a rolling bearing, a bore of a nest of a finished gear hub under an outer ring of a bearing and a neck of a finished axle or shaft under a diameter of an inner bearing ring within specified tolerances, assembling a bearing assembly in the form of a gear support on an axis or on a shaft given landing [1].

A significant drawback of the known method of manufacturing the bearing assembly is the insufficiently high degree of accuracy of machining the sockets, necks or pins of machine parts for the rolling bearing assembly and the very high requirements for mounting accuracy when assembling and adjusting the clearance of the bearing assembly, especially gear reducers, which ultimately affects strength and durability of the mechanism design.

In modern precision instruments, for example, microelectric machines, the diameters of the axle and shaft trunnions are chosen within a few millimeters, and therefore the strength of the joint of the inner ring of the rolling bearing with the trunnion is mainly created by the tightness of the fit with significant interference. For an optimal connection, the tolerance fields narrow to one micron. However, even such interference values lead to significant ring deformations leading to an increase in the diameter of the raceway. In addition, the correctness of the geometric shapes of the mating surfaces, which is mainly determined by their ovality and taper, is of great importance, since the bearing rings are thin-walled parts that are deformed during interference fit, taking the form of a seat. Both phenomena reduce the radial clearance in the bearing itself. With insufficient radial or axial clearance, the rolling elements can be pinched and lose the ability to self-align and change the plane of rotation. This can lead to the fact that the rolling elements, rolling along a constant raceway, quickly reached at individual points on the surface the limit of the number of dive cycles, and therefore maximum wear. Jamming of rolling elements in high-speed bearings is especially unacceptable, as this leads to their rapid destruction.

A known method of manufacturing a bearing assembly, including pre-processing with a given accuracy of the outer ring of the rolling bearing to obtain a finished mechanism part, for example, in the form of a gear ring gear [2], assembling the outer ring part with other parts of the rolling bearing into a single assembly, mounting the bearing assembly of the mechanism .

A disadvantage of the known method of manufacturing a bearing assembly is the unjustified consumption of expensive high-quality ball-bearing steel for the production of an entire part together with a rolling bearing ring. Mandatory heat treatment of the ring, made at the same time as a whole with the finished part, leads to warping of this part with further labor to eliminate its consequences.

The closest in technical essence to the proposed one is a method of manufacturing a bearing assembly, including pre-assembly of a rolling bearing and molding around the outer ring of the bearing from the plasticized material of the workpiece blanks of a given shape and size with embedded elements [3].

A disadvantage of the known method of manufacturing a bearing assembly is the low accuracy of the finished critical parts of the mechanisms obtained by processing the workpiece with a shaped bearing. As you know, casting from metals does not allow you to immediately get the finished part with high accuracy of the set dimensions and good surface quality and requires subsequent mechanical and heat treatment. Forming the finished part from plastics around the bearing ring gives a good smooth surface, but requires subsequent machining to obtain high-precision parts, which is determined by the accuracy of the mold manufacturing. However, the machining of a part manufactured by the known method with a whole molded rolling bearing becomes impossible due to insufficient structural base for setting the part to be machined, since it is occupied on the outer ring by rolling elements and a bearing cage, and the inner ring is a freely rotating part and does not can serve as a basic element.

The formation of a rolling bearing in a billet of metal alloys violates after cooling the mechanical properties of ball-bearing steel of the rings and rolling elements and the gaps between them, the effect of the selective selection of the connected bearing parts from one sorting group disappears. The use of a finished rolling bearing for molding is unjustified due to the non-use of a high-quality smooth outer surface of the ring, the receipt of which requires certain labor costs.

A positive effect on the proposed method of manufacturing a bearing assembly, including assembling a rolling bearing from the outer and inner rings, rolling elements, a cage, protective washers, forming the bearing ring into the plasticized material of the mechanism part, installing the part with the rolling bearing formed in it in the mechanism body with the formation of a support node and adjusting the gaps for a given fit, is achieved by the fact that the outer or inner ring is separately molded into plasticizable material ki, the blank is based on the free surface of the rings machined and treated to obtain the desired items on the accuracy of dimensions and shape, and then the finished part with overmoulded ring is collected in the rolling bearing as a single assembly.

In Fig.1 shows a bearing assembly built into the hub of the gear wheel of the gearbox, Fig.2 - bearing assembly of the support roller of the conveyor, made by the proposed method.

Example 1 implementation of a method of manufacturing a bearing assembly. The outer ring 1 of the rolling bearing is installed in a mold, which is filled under pressure with plasticized material (liquid aluminum, thermoplastic polymer, etc.). After the material cools down, the billet with the formed ring is mounted on metalworking machines, based on (base A) and end face (base B) of the inner surface of the ring, and, for example, gearboxes 2 of the gearbox are manufactured with the possible achievement of high degrees of accuracy in deviation of size and shape as gears in general, and its teeth 3 separately. Next, the gear with the molded outer ring is assembled with the remaining parts of the rolling bearing into a single assembly, mounted on the shaft or axis of the gearbox in the form of a support (Fig. 1).

Example 2. The outer ring 1 of the bearing is placed in the mold and pressurized with a thermoplastic polymer material. After cooling the material, the preform with the formed ring is mounted on a lathe based on the inner surface (base A) of the ring, and the conveyor roller 4 is made with minimal deviations in radial runout dimensions. Next, the roller with the ring is assembled into a single rolling bearing mounted on the axis of the conveyor in the form of support nodes (figure 2).

The need to improve accuracy and, as a consequence, increase the durability and strength of mechanical gears, requires today the technical re-equipment of ball-bearing factories for the manufacture of finished parts that are highly accurate in size and shape, for example, gear gears of commercially available gearboxes of various types and other engineering products, which becomes possible on the basis of implementing the proposed method of manufacturing bearing assemblies. It is at the factory of bearings that it becomes possible to form workpieces with built-in rings of rolling bearings, having a sufficient structural base for the manufacture of high-precision parts on metalworking machines with high adaptability and material consumption. At the same time, the outer molded surface of the rolling bearing ring may not be completely finished; it does not have axial and radial clearances. After assembling the part with the ring with the remaining parts of the bearing, the stiffness of the mating parts is enhanced.

The proposed method has been successfully implemented at a ball-bearing factory in the manufacture of a roller bearing assembly of serial transporting mechanisms.

Claims (1)

A method of manufacturing a bearing assembly, including assembling a rolling bearing from the outer and inner rings, rolling elements, a cage, protective washers, molding the bearing ring into the plasticizable material of the mechanism part, installing the part with a bearing in the mechanism body with the formation of the support assembly and adjusting the clearances for the given fittings, characterized in that the ring separately from the bearing is molded into the plasticizable material of the workpiece, the workpiece is based on the free surface of the ring on the machine and process to give details of the required accuracy of dimensions and shape, and the finished part with overmoulded ring is collected in the rolling bearing as a single assembly.

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