Typical bearing structures for evil - Details of machines. Course design

Typical bearing constructions for evil Fixing inner bearing rings to shafts

The bearing fastening is reliably performed by a round slotted nut (GOST 11871-73) (Figures 4.33, 4.35), which is secured by a multi-cup washer from spontaneous unscrewing (GOST 11872-73). The lock washer has one internal protrusion and six outer projections. The inner projection of the washer comes into a special groove on the shaft, and one of its outer protrusions bends into the slot of the nut. Dimensions of nuts and lock washers are given in Table. P. 125 and A.127.

Simple and securely fastening the endplate (Figure 4.36, 4.37).

The pivot from the rotation relative to the shaft is fixed with a pin (Figure 4.36) or by installing two diametrically disposed bolts (Figure 4.37).

To ensure that the end washers do not cause an imbalance at high speeds, they are centered around the hole

bearing (Figure 4.36) or shaft. In all cases, it is necessary to provide for the locking of the screws securing the washer to the shaft end, from self-unscrewing.

It is often enough to fix the inner rings of bearings on the shafts using split rings (Figure 4.38; Table A.297). Their installation and dismantling is carried out with the help of special tongs, with which the rings are unclipped.

The side bearing surface of the bearing on the shaft is also the surface of the thrust collar (Figure 4.36-4.38). A feature of the rolling bearing design is that its inner ring is a very compliant part. To

Fig. 4.36

Fig. 4.37

Fig. 4.38

the inner ring was installed on the shaft without warp, it must be pressed when mounted to the shoulder of the shaft or to the end of the part installed on the shaft.

The bearing ring must be adjacent to the thrust bead with its flat end face.

On the one hand, the height of the shoulder of the shaft must be greater than the height of the bevel of the bearing, on the other hand it should be chosen taking into account the possibility of removing the bearing from the shaft (Figure 4.39).

Fig. 4.39 Bearing mounting in housing

In Fig. 4.40-4.42 shows the most common ways of attaching bearings in the body.

Widely used simple and reliable way to secure the bearing in the body of the lid:

• the threaded (Figure 4.40);

• The mortgage (Figure 4.41).

In Fig. 4.42 shows the variant of attaching the bearing by a spring thrust flat ring (GOST 13943-80).

Dimensions of spring rings and grooves for them are given in Table. P.298. To fix the bearing ring in the body without a gap, a compensating ring is sometimes placed between the lock ring and the bearing.

For precise installation, the outer rings of the bearings are pressed against the shoulder of the body part. According to Fig. 4.40 4.42 The thrust collar is created directly in the body. However, the presence of a bead in the opening of the body part will create certain difficulties in boring the hole.

It is simpler to make the bead by installing a spring thrust ring (Figure 4.42). It should be borne in mind that the spring rings can transmit significant axial loads. So, for example, with a bore diameter of 62 mm, the allowable axial force for a spring thrust flat ring is 73 kN

The processing of the opening of the body part will be simplified if the bead is made in a glass (Figure 4.43). The introduction of an additional precise part (glass) is advisable only if the glass allows to solve some other design task - simplifying the assembly, creating an independent assembly unit.

Fig. 4.40

Fig. 4.41

Fig. 4.42

Fig. 4.43

In housings that have a connector along the shafts of the shafts, the thrust collar can be created by an entire ring embedded in the groove of the housing hole.

All the beads, made according to Fig. 4.40 ^ 4.43, are capable of perceiving significant axial loads. Fixing support Constructions of fixing supports

For axial fixation of shafts according to the scheme shown in Fig. 4.33 in the fixing supports (in Figure 4.33 - left support), the bearing types shown in Fig. 4.44.

Thrust beads on the shafts and in the holes of the body parts are constructed according to one of the variants shown in Fig. 4.36-4.36 and 4.40-4.43.

The stiffness of the fixing supports, in which the bearings are located according to the variants shown in Fig. 4.44, б, г, е, Z, is higher than supports with bearing arrangement according to the variants of Fig. 4.44, a, c, d, g.

Fig. 4.44 Adjustment of bearings in the fixing support

In some types of bearings (in radial and radial-thrust ball bearings, in radial spherical ball and roller bearings), the gaps between the rings and the rolling elements are embedded in the bearing structure. In other bearings (in tapered roller bearings) the gaps are formed when assembling the product. The presence of gaps in the bearings ensures easy rotation of the shaft, improves load distribution between the rolling elements, increasing the bearing capacity of the bearing, but reduces the stiffness of the supports and the accuracy of the shaft rotation.

In the bearing, radial and axial clearances are distinguished, interconnected. When designing the bearing assembly, various methods are provided for creating optimum gaps in the bearings, and, if necessary, creating a pre-tension. Clearances in the bearings are created and modified when assembling the product most often by axial displacement of the rings. Adjustment of radial or radial-thrust bearings of the fixing (in the figure - left) support according to the scheme in Fig. 4.33 can be produced by axial movement of outer or inner rings. Adjustment of bearings by axial movement of outer rings

In Fig. 4.44, a, c, f shows the adjustment of a set of gaskets installed under the flange of the bearing cover. For this purpose, a set of thin (thickness (0.05-0.1) mm) metal gaskets is used.

The bearing can be adjusted with a screw-cap screwed into the body (figure 4.45). In this case, the accuracy of bearing basing is reduced.

Fig. 4.45 Adjustment of bearings by axial movement of inner rings

In Fig. 4.44, b, d, s the bearing adjustment is made with a slotted nut. 11After the required clearance is created in the bearings, the splined nut is secured with a multi-cup washer. To do this, the nut must be installed in such a way that the groove on it coincides with one of the deflection tabs of the lock washer. Floating support

In the floating supports (right-hand support in Fig. 4.33), the bearing types shown in Fig. 4.46.

Fig. 4.46

A gap b is provided between the ends of the bearing outer ring and the cover in the floating supports.

The size of the gap in the supports made in Fig. 4.46, a, b, c, are taken equal to:

where/is the distance between the ends of the bearings' bearing rings. mm.

To attach the bearing rings to shafts or body parts, you can use the techniques that were shown in Fig. 4.40-4.43. Supports under the scheme in the spread Constructions of supports

For axial fixation of the shafts in Fig. 4.34 both legs are constructed identically. In Fig. 4.47 shows examples of the design of a single shaft support. The other support is similar.

Fig. 4.47 Bearing adjustment

The bearings are adjusted by axial movement of the outer rings.

In Fig. 4.48 shows the adjustment of a set of thin metal gaskets (1) installed under the flanges of the attached bearing caps.

To adjust the bearings, the gasket set can be installed under the flange of one of the covers.

If the shaft's axial position is additionally required, the overall set of gaskets is divided into two, and then each of them is installed under the flange of the corresponding cover. The adjustment of the set of metal gaskets provides a sufficiently high accuracy and is used both for the installation of radial and radial thrust bearings.

When installing radial ball bearings between the end face of the bearing outer ring and the end face of the bearing cover, a gap is left to compensate for the thermal deformations a = 0.2-0.5 mm (Figure 4.48). This gap in the drawings of assembly units, because of its smallness, do not show.

The adjustment of the radial-thrust bearings when using the lid covers are made only in Fig. 4.49, by operating the threaded screw (1) with a small step on the self-aligning washer (2).

Fig. 4.48

Fig. 4.49 Supports under the scheme in the stretch Constructions of supports

For axial fixation of the shafts in Fig. 4.35 both legs are constructed identically.

In Fig. 4.50 examples of the design of one shaft support are given, the other support is performed similarly.

Axial fixation of the shaft is carried out by the shoulder of the body, in which the ends of the outer bearing rings abut.

Fig. 4.50 Bearing adjustment

The bearings are adjusted by axial movement of the inner rings along the shaft by means of nuts.

To adjust the bearings, one nut is sufficient at one end of the shaft (Figure 4.51).

If the axial position of the shaft is additionally required, nuts are provided at both ends of the shaft (Figure 4.52).

Fig. 4.51

Fig. 4.52 Bearing shafts of bevel gears

The cantilever fastening of the pinion shaft is most often used in bevel gears. The design of the unit in this case is simple, compact and convenient for assembly and adjustment.

The shafts of the bevel gears are mostly short, so the temperature axial deformations do not play a big role. The distances between the bearings are relatively small, and the loads acting on the shaft and its supports are large. Increasing the rigidity of the assembly allows to reduce the load concentration with the cantilever arrangement of the pinion, and also to increase the accuracy of the axial arrangement of the conical gear necessary for the normal operation of the conical gear.

In the design of knots of bevel gears, tapered angular contact bearings are often used, more load-lifting and less expensive, in comparison with ball radial-thrust bearings.

Ball angular contact bearings are used at relatively high speeds (n & gt; 1500 rpm) to reduce losses in supports, as well as when high precision is required. Typical construction of the shaft of the bevel gear is shown in Fig. 4.53-4.55.

Forces acting in a conical meshing cause radial support reactions.

The radial reaction is considered to be applied to the shaft at the point of intersection of its axis with the normals drawn through the middle of the contact pads on the bearing rings.

Let's designate:

b - the distance between the points of application of reactions;

a is the size of the console;

(I - diameter of the vase in the place of installation of the bearing.

The design of the bearing assembly with the shaft of the bevel gear set in the bracing scheme is shown in Fig. 4.53.

Fig. 4.53

In the construction of this scheme, it is recommended to maintain the following ratios:

It is desirable to obtain a distance a minimum to reduce the bending moment acting on the shaft. After that, by the expression (4.66), the distance L is determined.

The bearing located closer to the bevel pinion is loaded with a greater radial force and, in addition, senses the axial force. Therefore, this bearing has a larger diameter hole in the inner ring than the right (according to the drawing) bearing. The node is very compact.

In the construction of the support assembly shown in Fig. 4.54, to create the necessary rigidity of the node it is necessary to observe the condition:

The node has significant node dimensions in the axial direction.

In the shaft design of the bevel gear shown in Fig. 4.55, fixing the support, for the convenience of adjusting the axial position of the gear, is enclosed in a glass.

The bearing nearest to the pinion is installed directly in the housing hole. This increases the accuracy of the radial position of the gear.

Fig. 4.54

Fig. 4.55 Supports of worm shafts
In the vast majority of cases, because of the large amount of heat released in the meshing zone (due to the low efficiency of worm gears), a combination of fixing and floating supports is used as the worm's supports (Figure 4.33 and Section and

Due to the large axial force acting on the shaft of the worm, the radial thrust bearings are used in the fixing support: tapered roller bearings or ball bearings with a large contact angle.

Since the radial-thrust single-row bearings perceive the axial force of only one direction, two such bearings must be installed in the fixing support to fix the shaft in both directions.

Ball angular contact bearings are used for continuous continuous transmission operation in order to reduce power losses and heat dissipation in supports, as well as to reduce the requirements for the accuracy of manufacturing parts of the assembly. However, the dimensions of bearings made using angular contact ball bearings, due to their lower carrying capacity, are greater than when using tapered roller bearings.

A typical example of a constructive solution of the worm support nodes is shown in Fig. 4.56.

Fig. 4.56

Other options for securing the floating (right-hand in Figure 4.56) bearing are shown in Fig. 4.36,4.37 and 4.38.

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